1

Carbon, Climate, and Soil Biology

NRCS Soil Scientist Ray Archuleta admires the soil aggregates present in a vegetable crop field during a workshop at Many Hands Organic Farm on July 25, 2016

photo by Jack Kittredge
NRCS Soil Scientist Ray Archuleta admires the soil aggregates present in a vegetable crop field during a workshop at Many Hands Organic Farm on July 25, 2016

“For most of history, few things have mattered more to human communities than their relations with soil…For the past century or two, nothing has mattered more for soils than their relations with human communities, because human action inadvertently ratcheted up rates of soil erosion and, both intentionally and unintentionally, rerouted nutrient flows.” — Breaking the Sod: Humankind, History and Soil, J. R. McNeill and Verena Winiwarter

Importance of Carbon to Soil

The primary human activity impacting soils is agriculture, and the soil nutrient most severely depleted in quantity by agriculture has been carbon. Conversion from natural to agricultural ecosystems has depleted the soil organic carbon (SOC) pool by as much as 60% in temperate regions, and 75% or more in tropical ones. Such conversion has resulted in losses of 8 to 32 tons of carbon per acre from some soils, mostly oxidized and emitted into the atmosphere as carbon dioxide.

But depleting sinks of soil carbon is harmful in two ways.
Adding carbon dioxide — the primary greenhouse gas — to the atmosphere increases retained solar heat in the planetary system and results in disruptive weather extremes such as we have been experiencing. Since 1975 the global level of greenhouse gases has been rising and average temperature has been increasing at a rate of 0.3˚F to 0.4˚F per decade.

Organic carbon is a primary component of soil fertility, contributing to tilth, resilience, and crop production. Losing soil carbon decreases crop yields in at least three important ways: 1) it diminishes available water capacity, 2) it slows the supply of nutrients available to crops, and 3) it degrades soil structure and physical soil properties.

Soil moisture content increases by 1 to 10 grams for every 1 gram increase in soil organic matter, which is 58% carbon. This increase can contribute to sustaining crop growth for 5 to 10 days between periods of rainfall – often a crucial period in areas of moderate precipitation.

Preservation and enhancement of SOC also enhances cation exchange capacity and improves biotic activity of micro-organisms, facilitating the supply of nutrients available to crops. SOC is the primary source of energy and nutrients for the soil biota, who are system engineers and whose importance to ecosystem restoration cannot be overemphasized.

Increases in SOC have also been found to enhance soil structure, making it less prone to crusting and compaction and aggregation — formation of the small raisin-sized clumps of soil in which many crucial biochemical functions can take place because they enable protection from excess oxygen or contain needed moisture.

Productivity gains with increasing SOC are large, especially when combined with inputs of other nutrients and irrigation, in soils with a clay content lower than 20% or in soils of sandy-loam or loamy-sand textures.

Much Current Organic Annual Vegetable Cropping is Destructive of Soil Carbon

Bare Soil

Carbon, which is fundamental to climate stability as well as to soil quality and productivity, continues to be lost by many current methods of raising annual vegetable crops. This is particularly distressing in the northeastern United States, where soils are thin and 70% of cropland is rated as highly erodible, twice as much as in the rest of the country.
Bare soil is perhaps the most obvious sign of these soil depleting practices. Such soil is exposed to wind and water erosion, provides no barrier to direct atmospheric oxidation of soil carbon, accumulates no biomass, and contributes to the breakdown of soil aggregates.

Tillage

Bare soil is common on organic farms because tillage is our primary method for controlling weeds and preparing beds for planting. But tillage has many negative side effects. From the farmer’s point of view it dries the soil, brings up and encourages the germination of dormant weed seeds, creates compaction at the bottom of the tilled layer, and sets back the growth of fungi and the soil aggregation they facilitate. From the climate perspective even occasional tillage is also directly associated with significant greenhouse gas emissions and soil carbon loss from soils with high organic matter content.

Many northeastern organic farmers have already adopted no till methods for better soil resiliency and reduced weed germination. They use diverse methods to avoid bare soil including extending cropping duration, cover crops, and various mulches and composts. In support of these methods, various appropriate bed formation and planting approaches have been developed including specialized dibbles and planters, broadcast systems, and transplant devices.

Cover Crops

For farmers, use of cover crops is a fundamental tool for building a healthy soil while raising crops. Cover crops can be temporary crops planted between the cash crops, crops to fix, catch or “lift” extra nutrients to the crop root zone, or permanent mulches. They increase soil aggregation, reduce nitrogen leaching, discourage wind and water erosion, decrease weed pressure, sustain microbial life, and elevate the microbial community’s fungal/bacterial ratio which aids plant vigor.

From the point of view of a sustainable climate, cover crops not only pump carbon into the soil like all plants but provide green and, after death, brown soil cover to minimize oxidation from atmospheric exposure. When they contain a mixture of varieties including legumes they reduce losses not only from carbon dioxide but also nitrous oxide, a particularly potent greenhouse gas.

The National Resource Conservation Service has done excellent work focusing on the benefits brought to soil by cover crops. Their booklets, lectures, videos, etc, have been important resources educating farmers about these contributions and how to manage cover crops in various cropping systems.

Biodiversity

The importance of a diverse soil biology can hardly be overstated for good farming. Plants thrive when part of a symbiotic underground community or ecosystem to which they supply carbon compounds that sustain microbial metabolic functions and from which they receive minerals, water, and an array of compounds synthesized by bacteria specifically to help them resist disease, repel predation, encourage pollination, and accomplish dozens of other biological functions.

Earthworms, termites, ants, insect larvae, nematodes, bacteria, fungi and others all also play a role in creating good soil structure, providing nutrient cycling, and creating the porosity, aeration and soil drainage which enable good water infiltration and storage.

Crop rotation is also important for biodiversity. Studies have shown that crops in rotation show increased soil enzyme activity and, if containing legumes, increased microbial biomass. Plant biodiversity also enhances soil carbon dynamics and increases the level of soil organic matter, while attracting a corresponding diversity of insects, pollinators, and other largely beneficial organisms.

Toxins and Fertilizers

For organic farmers, the absence of synthetic pesticides and fertilizers is basic. In much of US agriculture, however, chemicals are omnipresent. When perusing articles and studies about farming methods, one must be cautious. Reports of “no-till” practices often fail to mention concurrent herbicide use to control weeds. Yet toxins and synthetic fertilizers decimate the gains of biodiversity by either directly destroying microbial life or starving it by undercutting the symbiosis driving soil ecology. So students of soil science need to be clear whether or not synthetic chemicals were involved in the activities studied. When that data is available, the results for soil health can be surprising.

In reporting results from the Morrow Plots, the University of Illinois experimental fields continuously studied since 1953, for instance, Christine Jones reports: “They discovered that the fields that had received the highest applications of nitrogen fertilizer had ended up with less soil carbon – and ironically less nitrogen – than the other fields. The researchers concluded that adding nitrogen fertilizer stimulated the kind of bacteria that break down the carbon in the soil.”

Yet natural ecosystems such as pastures and forests that do not involve synthetic chemical inputs build, rather than reduce, soil carbon. Even ecosystems managed for human food production can sustain regular annual increases in soil carbon if following the above simple principles.




Conversions, Quantities, Calculations and Indulgences: A Primer

plant root carbon

Cross-section of a plant root, showing liquid carbon flowing to soil via the hyphae of mycorrhizal fungi. This carbon will support a vast array of microbes that not only retain carbon but also improve soil structure and soil tilth, enhance water-holding capacity, fix atmospheric nitrogen, solubilise phosphorus and provide minerals, trace elements and other growth stimulating substances to plants. Photo courtesy Jill Clapperton

Anyone attempting to make sense of calculations surrounding carbon cycling and soil carbon must first understand a little bit about quantities and conversion factors. Here are some basic facts you might find helpful.

Metric Conversions

First off, much of this literature uses the metric system of measurement. In case you forgot your high school lessons on the metric system, here are some useful conversions.

Length: one meter = 39.3701 inches; one inch (12 in. to a foot, 5280 ft. to a mile) = 2.54 centimeters

Area: one hectacre (10,000 square meters) = 2.4711 acres; one acre (43560 sq. ft.) = .40469 hectares

Volume: one liter (1000 cubic centimeters) = 1.0567 US quart (liquid); 1 US quart (liquid) = .94635 liters

Weight: one kilogram = 2.2046 lbs; one pound = .45359 kilogram

An additional complication concerns the use of the weight that derives from the ancient Germanic term for a large cask, or tun. In the US, one (short) ton = 2000 pounds. The non-US “conventional” system, however, uses the British Imperial (long) ton of 2240 pounds. Lastly, the metric tonne is 1000 kg or 2204.6 lbs, very close to the Imperial or long ton.

Temperature: one degree Celsius = 1.8 degrees Fahrenheit; 1˚F = .556˚C, water freezes at 32˚F or 0˚C.

Quantities

Carbon and Carbon Dioxide: The carbon atom has an atomic weight of 12. Carbon dioxide (CO2) is a molecule composed of a carbon atom and two oxygen atoms. Since each oxygen atom has an atomic weight of 16, the total CO2 molecule has an atomic weight of 44. Thus one carbon dioxide molecule weighs 3.67 times as much as a carbon atom, and carbon weighs .273 times as much as CO2.

People are approximately 18% carbon by weight. Wood is roughly 50% carbon, and soil organic matter is about 58% carbon. Typical soils, depending on level of compaction, weigh between 1200 and 1600 kilograms per cubic meter.

Before the industrial revolution and burning of significant amounts of fossil fuels, scientists estimate that the level of carbon dioxide in the atmosphere was 280 parts per million. We are now at 393 ppm. Anything beyond 350 ppm is considered unsustainable as it will heat the earth (greenhouse effect) beyond tolerable levels. One part per million of CO2 in the atmosphere is equal to 7.8 gigatons (GT or billion tonnes) of CO2 or 2.125 GT of solid carbon (for illustration, this is about a cubic kilometer of graphite).

Methane: This is a gas with the chemical formula of CH4. It is the main component of natural gas and a potent greenhouse gas, one unit trapping as much reflected sunlight as 25 units of carbon dioxide. It is produced by anaerobic respiration from bacteria, termites, and in the rumens of ruminant animals such as cattle.

Nitrous Oxide: This is a gas with the chemical formula of N2O. It is known as “laughing gas” due to the euphoric effects of inhaling it. Nitrous oxide gives rise to NO (nitric oxide) on reaction with oxygen atoms, and this NO in turn reacts with ozone. Considered over a 100-year period, it has 298 times more impact (global warming potential) per unit mass than carbon dioxide.

Note: When encountering calculations involving Methane and Nitrous Oxide, some writers will automatically convert them into their CO2 greenhouse gas equivalents (i.e. equate a methane molecule to 25 carbon dioxides, and a nitrous oxide one to 298 carbon dioxides). Be ready for these molecules to show up as CO2 conversions, without clear explanation.

Calculations

We can now calculate how much carbon is contained in an acre of top soil when that top soil is 6 inches deep and has an organic matter of 1%. We can also calculate how much carbon dioxide that carbon is sequestering.

Taking an average soil weight of 1400 k/m3, the top inch of a square meter of soil will have a weight of 1400 kilograms divided by 39.3701 (inches in a meter) or 35.56 kilograms, and the top six inches will have 6 times that much, or 213.36 kilograms. If the six inches of top soil in a square meter weighs 213.36 kg, by the magic of the metric system we see that the weight of a hectare of that top soil is 2,133,600 kg. But we want to know about an acre of it, so we divide by 2.4711 and find the answer is that 6 inches of top soil weighs 863,421.1 kg per acre. Now only 1% of that is soil organic matter (SOM), so we now have 8,634.211 kg of SOM. And only 58% of that is carbon, so we are down to 5,007.8 kg of carbon.

That is pretty close to 5 tonnes (metric tons) of carbon, so lets call it that. Since all that carbon was put there by the magic of photosynthesis – the plant using sunlight to combine carbon dioxide (CO2) from the air with water (H2O) from the soil to make carbohydrates (usually with the form Cm(H2O)n where m could be different from n ) for the plant and giving back oxygen to the air – we know those 5 tonnes of carbon came from 3.67 times as much carbon dioxide. So the answer, dear class, is that the acre of top soil with 1% organic matter has sequestered 18.35 tonnes of carbon dioxide.

Indulgences

That’s no slouch of a number. The average US citizen’s share of emissions, with all our fossil fuel addictions, according to the United Nations is less than that much carbon dioxide annually (17.5 tonnes to be exact.) Of course the average Bangladeshi emits 0.38 tonnes, and your typical Zambian manages only 0.19. But if you are looking for a way to assuage your guilt and justify your lifestyle to posterity, building a percent more organic matter in the top soil of an acre of your field or yard or community garden every year is not a bad way to go about keeping your head held high!

How does this calculation hold up for the task at hand globally? Hold onto your hats!

If we are at 393 ppm CO2 in the atmosphere now, and want to get back to the sustainable level of 350 ppm, we need to store 43 ppm somewhere. If each ppm is equal to 7.8 GT of CO2, we need to store a total of 7.8 GT times 43, or 335.4 GT of CO2. This may seem like a daunting task, even for organic farmers. But let’s do the numbers.

The land area of the globe equals 149.4 million square kilometers. If you take the 38% of that which the World Bank says is agricultural land, you have about 56.8 million km2. This, again by the magic of the metric system, is 5.7 billion hectares. One has to look up the conversion factor, of course, to find that this equals 14 billion acres.

If an increase in 1% of the organic matter of soil in an acre will sequester 18.35 tonnes of CO2, then 14 billion acres could sequester 256.9 billion tonnes. This is more than three-quarters of the CO2 that we need to sequester to get back to 350 ppm, the level of sustainability – all for increasing soil organic matter by one percent!

None of this, of course, would be easy. But isn’t it nice to know that soil can do that? It even turns out that with proper practices much of that carbon can be stored for centuries as humus. And the best part of it is that doing all this will improve the fertility and water retention capacity of your fields, give you better crops and make you more productive as a farmer.




Why “Carbon Farming”

Collard greens in mown living legume mulch. This is a great way to build carbon while growing annual vegetable crops.

This issue of The Natural Farmer focuses on the question of how organic farmers in the northeast can adopt methods that build soil carbon. This is a pressing question, as readers of this journal know, because greenhouse gases, primarily carbon dioxide, have been building up in our atmosphere from burning fossil fuels and uncovering soil. Those gases trap solar heat and warm the globe, causing extreme weather events, melting polar ice, and making the planet more and more uninhabitable.

Reversing global warming will require drastic reductions in emissions, which will be a challenge to our consumptive way of life. But reductions will not be enough. Greenhouse gases have long half-lives and will remain active, unless removed, trapping and building atmospheric heat for another century.

To avoid that we need to return much of the carbon that we have taken from the soil. The only feasible method to use for this is the biological process of photosynthesis by which plants use sunlight to break apart carbon dioxide and water, recombining them to form carbohydrates and oxygen. Some of those carbohydrates are exuded by plant roots into the soil and drive an underground ecology that both strengthens plants and sequesters some of that carbon.

Farmers are the primary people who manage soil and plants on this planet, and we are in the best position to return that soil carbon. There are three reasons why we might want to do this. First, it is our best hope to survive on a habitable planet. Second, governments are going to get involved in requiring soil practice changes, and they are likely to do so by setting up incentive programs that can benefit farmers who adopt these changes. Third, carbon in soil means bigger, stronger, healthier crops.

The biggest change we must make involves not exposing bare soil to the air. Every time that happens, soil carbon is oxidized and becomes carbon dioxide. Tillage is a primary offender in exposing soil. Organic farmers, particularly, use tillage to control weeds and prepare beds for planting. We need to find better ways of doing these, and to harvest so that soil continues to be covered after a crop is taken off.

Another way to destroy soil carbon is by farming with synthetic toxins, chemicals and fertilizers which either kill or shut down the underground organisms that feed plants and store carbon. Organic farmers have wisely rejected such chemicals, and have found natural materials and processes that encourage, rather than undermine, this soil ecology.

Farming in ways which will build more soil carbon won’t be easy. But farmers have always been tinkerers and innovators. Some are already experimenting with methods to keep soil covered with green plants: using cover crops, extending the season, raising more perennials. Others are trying to manage weeds by solarizing them, shading them out, or using cover crops and mulches. Some use nutrients from rock powders, brown and green manures, fermented fungal products, and inoculants that enable biological solubilization and fixation.

This issue of The Natural Farmer explores early steps in this direction. We interview farmers experimenting with these practices, read some science on the problem, view a presentation by a pasture expert on sequestering carbon, learn about a few practical testing protocols to measure carbon’s impact in soil, and see what is being tried at one of the region’s premier agricultural companies.

From what we are learning, raising organic annual vegetable crops is one of the more challenging kinds of carbon-friendly agriculture. A lot more needs to be learned, and we hope this issue prompts you to get interested and try out a few things that make sense in your operation. The more of us who are involved and gaining experience, the clearer our path will be!




Intensive No-Till at Woven Roots Farm

photo by Jack Kittredge
Pete Salinetti stands in front of some of the beautiful crops he is growing by precise successions in Western Massachusetts on October 2.

The Berkshires, formed as they were some 300 million years ago by the collision of the supercontinents containing North America and Africa, have had time to adjust. The intense pressure of the tectonic forces that buckled and folded bedrock into fused slabs has dissipated. Millions of years of rain and wind have eroded the jagged peaks that were forced up. Freezing and thawing have cracked and splintered their surfaces. Slowly life has arrived, with its microbial acids and enzymes, and further degraded the rock until now a thin coating of soil covers it and what were mountains are now not much more than steep hills.

The collision has left its mark, however, in exposed geological formations everywhere. Some have attracted the attention of commercial developers and become quarries and mines, especially the deposits of marble and the mile-wide belts of dolomitic limestone present in 500 to 800 foot thick layers. It was the former of these that brought Pete Salinetti’s family to the area over a hundred years ago.

“They were all from Northern Italy,” he explains, “and were fine stone cutters. They ended up in Lee, Massachusetts, cutting slabs of marble. Nobody sells marble there anymore, though. Now they just blow it up and sell it as limestone!”

Pete grew up in Lee, next door to his grandfather, where his family had an extensive garden. He never thought he would farm for a profession, but he loved to garden and grew ornamentals and perennials, including orchard fruit.

Pete and Jen met at the University of Massachusetts in Amherst, where Jen was in the nutrition program. She had grown up in New Jersey, was a vegetarian since she was twelve, and was dealing with some personal health issues. One summer she interned with Seeds of Solidarity Farm in Orange, Massachusetts and had her eyes opened to the truth about food being our best medicine. She also learned that how that food is grown matters very much.

“Getting that hands on experience in where food comes from,” she recalls, “hit a place in my soul that I’d never felt before. I decided this was of utmost importance and I wanted to pursue it. I decided to design my own major around agriculture at UMass. At the time the only ag program there was very conventional, primarily industry-driven. Or you could study turf grass management!” (she laughs)

Pete and Jen met in college and he took her home to his family’s garden. She’d never experienced anything like that before. The most she had seen was an aunt and uncle in Brooklyn who grew tomatoes. So they began to inspire each other about growing.

Upon graduation the couple rented Pete’s grandfather’s old house in Lee and began looking for land to farm. Jen did design installation and maintenance for her own landscaping company, and Pete worked at a local nursery and orchard. While they were looking, however, they figured they might as well farm where they were in Lee. Pretty soon they had two kids, a small CSA, and were full time farmers!

“We were reluctant to start a CSA in Lee,” says Jen, “because we knew that was a temporary living situation for us, and while we wanted to be nearby we weren’t sure that we would be able to find land nearby. But we had ten really dedicated households that were good customers at our honor box farm stand. They were nudging us to go to a CSA. We told them our goal was to get really good at growing and then move into a CSA model. They said: ‘we’re ready, we’re ready. We’ll sign up and move with you to where you end up.’ “

photo by Jack Kittredge
The farm’s carrot beds show off the beauty and productivity of
Woven Roots precision methods.

Where they ended up turned out to be in Tyringham, just 7 miles from Lee. Four years ago they found land there they were able to buy and build a house on, next to a field they could lease. Of those ten original CSA families, nine are still with them and just one moved away. They now have 75 households as members. About 50 percent of their food goes to the CSA, and 50 percent is sold wholesale.

“The Berkshire Coop Market,” Jen says, “is our primary wholesale account, and we also sell to Guido’s Fresh Marketplace in Pittsfield, and to a friend with a restaurant in Lenox.”

The biggest constraint on the Salinettis’ farming operation has been their lack of enough land. Pete’s family land in Lee allowed them to have only about an acre and a half in production with nowhere to expand.

“Besides,” says Pete, “it was right next to the turnpike and the back border was a lime quarry which is still active. Then right up the street is a rifle range. So it was hard to even think there!”

They still farm it now, however. Although it is a hassle to farm in two locations, there are reasons to do so. For one, they’ve been working the soil for 16 years now and have really built it up. In addition, being right next to Lee Lime they never had to add limestone to make the land less acidic. The land there was heavily clay, initially, and the only thing that would germinate for them was beans. But by the time they moved away they were growing carrots in Lee.

On their Tyringham land there is a clay component, but there is also sand, depending on where you are in the field — the lower parts have heavier soil, the upper parts are sandier.

photo by Jack Kittredge
Jen stands by pole beans which are climbing sections of cattle fencing tied together to make a tent-like growing frame. This is also used for cherry tomatoes and other climbing crops.

“We think it has to do with glaciers,” explains Pete. “There is a giant rock that might have been left by glaciers, but then something dropped a lot of topsoil right here. Anywhere else in the valley it is nothing but rocks, except here! It is very unique. We dug our cellar hole and there was one rock! But at the same time it is a very heavily mineralized soil.”

Right now all told the couple has about 5 and a half acres under cultivation. But even though they are at 1700 feet of elevation, however, they try to extend that acreage by a rapid succession of crops. Jen figures that five and a half acres is equal to about 17 acres when you calculate the multiple successions they take pains to maintain throughout the season.

“Much of our state agriculture is now on smaller, more productive areas,” says Pete. “Unfortunately state program’s haven’t kept up with that change. We can’t put our land in the APR program (Massachusetts farmland property tax relief program), for instance, because it is 4.9 acres and the program requires 5.0 acres!”

The couple hopes eventually to be able to lease or buy more land, however.

“It is a beautiful farm,” Pete sighs, “a nice place to grow up. The people who own the land we lease also own a private pond up the road where we can swim. This summer that made a big difference!”

Both Pete and Jen share the concern about raising the highest quality vegetables possible. To them, a key part of that is to raise their crops without tillage.

“When we were at UMass,” Jen points out, “they didn’t really teach about no till. We had to figure out how to do it ourselves — we’ve been doing it for ten years now. Pete was experimenting with it in smaller beds at first to see if it was something we could use in larger scale production.”

“We found that it was really clumsy to use our walk behind rototiller in greenhouse production,” he explains. “So we did a lot of experimenting in the greenhouse doing winter growing of greens without tillage, for ourselves. We also did a lot of fooling around with different dates for season extensions of different crops.”

photo by Jack Kittredge
Diego uses scuffle hoe on newly seeded bed. Note how flat and perfect the bed is. In a month a new, 20 by 50 foot greenhouse will go up here.

Jen adds: “We struggled with the general idea of using a tiller. We didn’t like the reliance on fuel, didn’t like the environmental impact of using fuel, and also didn’t like the way the soil became powder every time we would till.”

“I was starting to see improvements in the greenhouse with no till,” Pete says, “but outside, with a heavy clay soil, I felt I was coming back to square one every time I would till, in terms of compaction and no structure, aggregation, porosity, or movement of water through the soil. Over a season of mulching and not tilling you could see the results of microbes and earthworms doing the work — how beautiful the soil surface would become and how nice the porosity was. Then to go in with a tiller and see it all get destroyed, it felt like starting over again rather than increasing what we already had going on.”

Eliot Coleman helped encourage them in this direction. They took an intensive course with him at a NOFA conference a while back.

“That was a couple of years after we started playing with it ourselves,” Peter remembers. “Just to hear that you can make a living on a very small farm, can build your soil without rototilling and without plowing, just to see the hard numbers and realize that it is possible was great. We were still working the other jobs and just had a market garden and people who were encouraging us to get into farming. We were selling the few crops we could grow wholesale.”

Instead of tilling, the Salinettis have found other solutions for the problems tillage is supposed to solve.

photo by Jack Kittredge
Pete shows his six-row seeder. It can plant from one to six rows at a time, at four different speeds and with 4 options as to seed size, The seeder itself is about 15 inches wide and has front and rear rollers which flatten the bed before and after the seed is planted. In this shot the hopper cover is removed to see the inner works better.

“We deal with weeds strictly by hand cultivation,” Pete asserts, “mainly stirrup hoes and wire weeding. But basically we get weeds before they become an issue. We like to get seeds in the ground by April 1, so I will use solarization to warm up the soil in the spring. Mostly we use it for carrots, Japanese turnips, radishes, salad greens, spinach, arugula, broccoli raab – the same crops we have been planting now for the last three weeks! We’ve come full circle!”

The solarization is done with greenhouse plastic. Pete monitors the top 4 inches of the soil for temperature. How long he leaves the plastic down depends on the weather, sometimes snow is an issue. He likes to achieve at least 45˚F soil temperature at 4 inches down before putting seeds in the ground. That way he can get those seeds to germinate. It may take a week to ten days to bring it up to that, but once they germinate he figures they are going to go on growing when they are ready to. He doesn’t do anything after that.

“The other thing that we do,” Pete says, “in terms of weeds, is stale bedding. We’ll prep beds and irrigate them to get the weeds to germinate. Then we go through with a flame weeder to flame those off, seed our crop (something like carrots will take 5 to 8 days) and go through with a flame weeder again to eliminate the weed problem just before the crop starts to grow. This is hard in the spring because the soil temperature is low, but in summer months we do it a lot.

“We sometimes then have to still do one hand weeding,” adds Jen, “but after that the crop has grown tight enough to create its own shade. The walkways and surrounding areas we try to get to before the weeds are a few inches tall. We don’t want them to flower and go to seed. They provide a green manure – it is minimal but helps over time.”

“Timing,” Pete insists, “is everything! If you do weeds when they are small it is not a lot of effort. It is like just dancing through the field! If you can keep those top three inches clean, anything underneath there is not going to germinate anyway. So if you’re not tilling and bringing those seeds back up, you are letting sleeping weed seeds lie. We do a lot of transplanting. So that means hand seeding and plug trays in the greenhouse. The trays go to an 806 flat, then get planted out in the field.”

The couple often kills sod and opens up a field to vegetables by laying down cardboard and mulch and applying compost to the cardboard area. The following year that field will be workable.

photo by Jack Kittredge
Lettuces in center of field are a major crop for Woven Roots, and show the care with which they lay out their beds and plantings.

Jen gave Pete a broad fork as a gift when they were in their twenties. They have four of them now and only use them to aerate, never turn the soil. But they do that aeration religiously, before every planting. They use an 18 inch model and go up one side of the 30-inch row and down the other, every six inches.

“You stand in the aisles,” Jen instructs, “and do it angled on each side, walking backwards from the aisle. We try never to step in the beds. We got it from Peace Valley Tools. We haven’t found a 30 inch one that is strong enough. It would take a lot of strength to use it, too! This one is heavy at 18 inches It is all-steel construction.”

Jen wants to increase their efforts to build soil carbon in the future. Once they have more land she would love to establish a collaborative effort with an animal farmer, for instance, and points out they bring manure in right now to make compost and being able to get into more of a rotational system with animals would be great for everyone.

“In the last 3 to 5 years,” she says, “I’ve been seeing a real shift in the interest level of people in alternatives to tilling. We have people reaching out to us from all over, asking us to let them come and see the farm and what we do. We’re the only farm in this area that is practicing these methods. The nice thing about our farm practices is that they are applicable to a home gardener – not relying on large, expensive equipment. When we were feeling our way through this 15 years ago the resources weren’t there the way they are now. I see the interest in NOFA – NOFA is doing a fantastic job of bringing together more resources around this – because the drive to do it is out there.”

One of the ways the Salinettis seem most Eliot Coleman-like is their thoughtful planning of intensive rotations and successions.

“Every spring,” explains Pete, “I plan out where the crops will be and the successions. Of course things move and it depends on the weather and other things. But roughly we have the plan. There are tricky ones, like the tomatoes. All you can really get in before tomatoes is a bunch of radishes or some lettuce. You have a June planting and a week to prep it, so there are tricky ones. It also depends on how long you want to keep existing crops in the ground. We ripped out eggplant three weeks ago so I could get fall seeds in the ground and a new crop out of that piece of soil. We could have kept the eggplants going, but it wasn’t really worth the dollar value for what was in there. A better use of space is to rip them out, give whatever is left to the CSA, and plant it with a fall crop that will produce us some more income.

“I will roughly put it all down,” he continues. “Like, I need this land for storage carrots on June 15, what can I do before that? Something that will be out of the ground in time for us to re-prep for the carrots. It is all fluid. We try to think of it as taking care of your land as best you can. Therefore we are getting that much more production out of it. We’re not letting the weeds come in, for instance. We don’t have the down time between harvest and next year. I’m carefully calculating how long a crop needs to be in the soil and being prepared for that soil to receive a transplant or seeds as soon as a crop is done.

photo by Jack Kittredge
Diego (12 ½ years old) and Noelia (10 ½ years old) hold radishes they have just picked. Both go to a Montessori school in Lenox and after 8th grade will go to the local high school. photo by Jack Kittredge

“We focus very highly on plant spacing,” Pete concludes, “and how close you can plant and still maintain optimal health. So that and we are getting 2, 3 maybe 4 crops per bed per season. That was the only reason we were able to make anything off a piece of land as small as we had in Lee. Ideally, I feel that where we are now, which is about 5 acres open in field production, supporting a crew of four full time people plus the two of us, working throughout the season just at that size can work. We try to grow just a little bit each year because we like to maintain an intense, weed-free operation. It is hard to say how much land would be ideal, or if that would change the way we do things if we got much bigger.

When it comes to bed preparation the couple tries to leave as much root matter in the ground as possible. When they harvest lettuce, for instance, they twist them out just enough to get the knuckle so it doesn’t regrow and leave as many plant roots in the soil to decompose as possible. They figure that’s better than putting them in the compost and then putting them back in the ground.

“We do as much bed prep as possible in the fall, ahead of time,” says Pete, “with soil aeration via the broad fork, applying compost, and lightly incorporating that into the surface with a rake or tilther. A tilther is a mini tiller powered by an electric drill that tills about an inch deep. By using that we’re not messing with any of the soil aggregation further down but we are able to incorporate organic matter into that top inch of soil. Or you can just use a rake. We also spread an organic alfalfa powder for nitrogen and a little crab and lobster waste for calcium and magnesium.”

They get compost from New England Harvest as well as making some. The recipe is to use a 5 gallon bucket every 8 running feet of bed, just shaken on by hand. That amounts to 5 gallons of compost every 20 square feet, applied every time a bed is planted. So it can be once, twice, three of even four times a year.

“I think we lose a little carbon to volatilization on the surface,” Pete says. “But I think the compost that gets involved with the aggregates under the surface is captured. So we are losing some carbon but if you incorporate it deeper you could destroy some of the aggregates and could potentially release more stored carbon than your surface application includes.”

The one thing Pete is passionate about is that to have consistent germination you have to have flat beds.

“We spend a long time doing that,” sighs Jen. “He used to lay out newspaper and practice on this dining room table! Pete has the final say when it is done. Think flat like a pool table”

Pete says: “I tell my employees: ‘You do me a favor and make that bed almost perfect. Then I’ll come in and make it absolutely perfect.’

The reason Pete stresses the bed’s flatness is that he uses a hand seeder – his is a 6-row one – which makes for really tight spacing. For that 6-hopper setup he feels you really need a clean, smooth surface. The seeder drops the seed at the proper depth but if you have humps or dips it will bury it too deep or not at all.

The seeder itself was designed by Eliot Coleman and is distributed through Johnny’s Selected Seeds. It is about 15 inches wide and has front and rear rollers which flatten the bed before and after the seed is planted. The rear roller also, through a belt, drives a shaft with holes in it of 4 different sizes. The shaft can be moved sideways so that 6 holes of any particular size can line up with and take a seed from 6 seed hoppers. Any number of hoppers can be used to plant a bed, up to six.

“Sometimes I’ll do 3 rows in a bed,” explains Pete, “sometimes 1 or even all 6. It took me a couple of years to learn how to really use that seeder, but once I did I find it is really effective at spacing. There are a couple of knobs on the side that adjust the front roller, which makes the hoppers go deeper. It is all driven with a belt from ground friction. This belt can be put on these wheels in three different ways to deliver 1 inch, 2 inch, and 4 inch spacing between plantings. It just turns the shaft slower or faster. It’s called a six-row seeder and takes time to learn to use it, just like any good tool.”

photo by Jack Kittredge
Jen holds a bouquet of radishes. In the background are farm beds with a crop of kale. In the far background are Jersey cows belonging to the neighbor running a dairy on land the Salinetti’s hope they might farm one day.

When raising seedlings each spring in Lee, Jen and Pete had a greenhouse with a hotbox in it.

“That is a trench that is 4 feet deep into the ground by 32 feet long,” Jen says, “and we’d bring in fresh manure and lay it 18 inches deep. We’d let it break down for a couple of weeks and generate heat. Then we’d put pallets over that, and all of our plug trays. After the seedlings germinated indoors, we’d bring them into the hotbox and put insulation over the whole box at night. It would maintain a temperature of 60 to 65 degrees when it was zero outside.

“We would come into the greenhouse in the morning,” says Pete, “turn the heat on to get it up to temperature, and uncover the seedlings. We started it in mid to late February. We plan on building that again, here. It was amazing. It cut back our use of heat tenfold.

When planting seedlings, the couple finds that usually the soil is soft enough that they can just use a marking rake to set up a grid system and then make holes at the intersections with a finger or hand.

“The marking rake lets us set our teeth at the right distance apart,” says Pete, “so we can be consistent with our placements. We string lines to make sure the grid is straight. In some of our newer soil we may have to use a trowel, and for something like leeks we use a dibble to make sure we can bury them further into the soil.

“We don’t broadcast seed,” he continues. We focus so much on optimal spacing that if we broadcast we would end up spending a lot of time on thinning, which could be a waste of labor. So I try to keep the precision of the seeder.”

I wondered about exposing so much soil and compost to the air and asked if the pair ever used mulch.

“We used to use mulch a lot,” Pete answers, “and on bigger crops we are getting back into that. But once we switched to tighter spacing and more succession in a season we found mulch to be almost a hindrance. You are constantly having to remove the mulch to re-prep the bed. We use it on tomatoes to some degree just to keep down the soil splash. But it is hard to find good mulch at a reasonable cost. And it is hard to find mulch materials that are seed free. I bought some last season that the guy swore was weed free. You should see the stand of weeds we have there now!

“I’ve been using straw,” he continues. “Leaves are good, too — they are ideal. We chop them up with a mower of some sort, or compost them a little first until they are broken up. Mulch can be challenging because of our seeding system, but I’d really like to reincorporate more in our system again. It’s amazing to see what is going on right under that mulch as opposed to in bare soil — microbes and earthworms, tons of porosity, free fertilizer from the worms!

When it comes to using cover crops, the couple struggles with trying to incorporate more cover crops into their practices. They haven’t figured out yet how to do that and still maintain their permanent bed system without using a tiller. They are adding a lot of compost, though, and feel that adds organic matter without cover cropping.

“The reason we haven’t gotten there yet with cover crops,” Pete admits, “is that we need to have a little wiggle room with the amount of space we have and what we need to produce. Then we can put fields and beds into fallow and cover crop them for several seeding periods. But we haven’t worked this in because we are using land so intensively.

photo by Jack Kittredge
One of the CSA members carved this 2-sided sign for the farm. It is made of cherry taken from the Salinetti’s land. It turned out to be so heavy that Pete and Jen are keeping it on their porch until they devise a sturdy way to hang it.

“Cover crops are one thing when you are talking broccoli and cabbages,” he continues, “which you can undersow. But if you see a field when it is finished there is no room for anything else, including weeds. We’re talking about clover in the walkways, but you have to beat back the clover that begins to creep into your bed each time you replant. How do you do that? Do you do it with a roller? Do you need to replant? Do you cut it with a shovel? I’m scared to create more labor.

“Our fields are pretty full late into the fall,” adds Jen, “and we overwinter many crops in low, quick hoops which will wake up in the spring for an early harvest of onions or spinach. So we can’t cover crop much for the winter, even.”

Both Jen and Pete feel that their growing practices have helped them considerably this year with the drought. They have more moisture in the soil than many area farmers because of their lack of tillage. The farm in Lee has been under no till for longer than the land in Tyringham and they can see the difference. But it is not as though they were able to ignore the lack of water!

“Out of 15 years in farming,” says Jen, “this is the most we have ever watered. We usually water when we put transplants in. But generally we don’t water them again. When we seed a bed, we will keep the soil moisture as consistent as possible until the seeds germinate, and then we don’t water again. We’re not looking to have a permanent irrigation system because generally we don’t need it.”

“But this year was different,” says Pete. “We had to move irrigation hoses around all the time. We do some drip, but it doesn’t really work that well for us because we grow so many lettuces and other short season crops that it isn’t always worth it to set the irrigation lines up and then have to take them down again so quickly. If we are growing carrots they are in 12 rows, but if we move lettuce in next it will be in three rows, broccoli in one. . And we want to keep up with our rotations.”

This year the irrigation water came from their strong well which has a 27 gallons a minute supply of water, but of course the pump was running most of the time and that is expensive. The couple has a border along a brook, but that was bone dry. They also have permission to draw water from a spring high on a nearby hill, which was running this summer, so perhaps that will be their irrigation in the future — gravity fed!

Flea beetles are major pests for the Salinettis, who use low tunnels to protect their brassicas from the insects.

“We have collards, bok choi, mustards, arugula, and broccoli raab under tunnels right now,” says Pete. “It is more a precaution. We don’t know for sure they are going to be attacked, but if they are it’s hard to get the flea beetles off. They grow just as well under row cover as not. We often get foliar damage on their leaves when they are young, otherwise. Usually when they get to a certain size the growth chemicals change and we can uncover them. But at the beginning for a transplant of arugula, for instance, if we don’t cover them for the first 2 weeks they almost all get killed, they are so heavily fed on.

“We also,” he continues, “have to cover our cucurbits for 2 weeks after transplant for cucumber beetles. After that we let them go. Cabbage maggot was devastating last year, too. It will kill a seedling or a full size plant in one day. With a broccoli you have a 30 inch spacing for enough room, so it’s been in the ground for 90 days, and then the whole plant goes down! Right now our broccoli is at the other farm. We lost 50% to 70% of every brassica on the farm to the maggots. Besides kale we didn’t grow any brassicas on this farm all summer long. We grew them on the other farm. We’re lucky to have that other location.”

One of the crops that have personal significance for Jen and Pete is beans. They raise some Italian pole beans that Pete’s great grandfather brought over from Italy and the family has been growing ever since. And they also have some Rwandan beans they brought back from a trip there 4 years ago.

“These Rwandan ones are delicious at any age, fresh or dry as a storage bean,” Jen says. “They are called ‘Land of a Thousand Hills’, which is also a name for the country. We were invited over there to work with a non-profit called Gardens For Health that was working with people coming out of critical malnutrition situations. It helps them learn how to grow their own food and create nutrient rich meals. Our participation was to help them create a composting system. Since they have a wet and a dry season a big issue was how to compost during the wet season. It turns out that banana leaves are a good covering to shed rain. They require reapplication, but there is an abundance of banana leaves everywhere.”

“These Italian ones,” she adds, “are white until they get exposed to the sun and dry down. They get red then. The CSA picks them and you can eat them raw when young or as a dried bean when older. They’re delicious.”

Sharing the farm work with the family are four employees, three of whom who worked there last year as well.

“Most take on other work during the winter,” Jen says. “One does substitute teaching, another was a private tutor for a student in the school system so also was employed by the school, another picked up a job at the local package store. They find various things. Our youngest is an 18 year old and the oldest is in the mid 30s. We start them off at $10 an hour and our highest paid employee is at $14.

“We try to provide other perks,” she continues. “They get as much food as they like, we have farm meals for them every day, we do a coffee break and then we provide lunch. We’ll send them to conferences – the NOFA conference or the Bionutrient one.”

Anticipating the next issue of The Natural Farmer which will feature stories about farm labor and a living wage I asked them how they felt about the idea of paying a $15 an hour wage.

“None of us get paid that much,” Jen replied, “and we’ll be shut down if that is the law! It is terrifying, to tell you the truth. We have been trying to figure out, if there isn’t an exemption for farms, how we are going to stay in business?

“A big part of why we chose to go to full time farming,” she continues, “was because we wanted to be with our family – present and available and engaged in family life. To take that away and say the best choice for you is to go off and work at McDonalds or elsewhere for a higher wage – is that up to the government?”

“I think there should be some exemptions,” Pete added. “Either exemptions for farms, or we need to have people really willing to pay what the true cost of food is.”

One of the real rewards that both Jen and Pete mention about their farming experience is the enthusiasm of their customers for their food.

“Having people reach out to us and tell us how good our product is,” Pete says, “and that we should be proud to be sharing that with our community – it’s an amazing and good feeling to know that you are providing food for other people.”

Jen adds: “People tell us: ‘I remember when I was growing up I would taste food like this!’ The rise in industrial agriculture has totally shifted the way food tastes. Having something taste the way it did several generations back is really significant! We have parents who tell us: ‘I never thought my kids would eat vegetables. Now there is this huge palette that they are asking for!’ It is really touching, that kind of feedback. It feels like we can make a difference in the world.”

The Salinettis are planning a lot more improvements in their farming infrastructure as soon as they can afford them.

“We have a sunroom that someone was getting rid of from their house,” Jen says, “which we are planning to add to the east side of our house for propagating seedlings. Our home is already passive solar, which is remarkable, but one of the other next steps we want to take is to build some infrastructure around solar power. Also, we’d love to have a winter CSA, but we need a root cellar and more greenhouse space.”

One of the innovations they employ is making tents of sections of cattle fencing for beans and cherry tomatoes and climbing crops.

“They’re galvanized so they don’t rust,” Pete notes. “Compared to stakes, with the price of new ones and the labor of taking them out and storing them, these are more efficient. One of these trellises can house 6 plants, so that is the same as six $3 stakes which last only a few years.

“Cherry tomatoes are the only problem,” he continues, “because they grow so rapidly that you have to be on them every other day so they don’t grow through the other side. Once they do that it’s hard to get them back. With the beans when they are a foot tall I put a piece of string along the fence to pull them towards it and then once they grab it they go.”

On the program front, Jen and Pete are interested in doing more educating around their growing practices and how their choices around food have social impacts. They’d like their space to be a more welcoming one and to share it with artists, musicians, nutritionists, and other educators. They already conduct workshops and their CSA has events twice a month for children. Off farm they run a garden program at the Montessori school as well as an intensive at the local high school.

“In the long run we’d also like a barn housing an educational center, a commercial kitchen, a bakery for Noelia (who makes delicious pastries) and a farm stand. We have lots of ideas! It’s all fresh right now!




How Biochar Works in Soil

Biochar first came into broad public awareness through the example of the Amazon, where the hypothesis is that Amazonian inhabitants added biochar along with other organic and household wastes over centuries to modify the surface soil horizon into a highly productive and fertile soil called Terra Preta, which is in direct contrast to the typical weathered Oxisol soils in close proximity. Biochar is exciting to many people because of its role in such soil-building processes. Those who have used biochar for several years may obtain tangible positive results, but they may not have solid concepts and theories about how it works. Biochar is a heterogeneous and chemically complex material and its actions in soil are difficult to tease apart and explain mechanistically.

The Role of Carbon in Soil

The evolution of soil shows how the soil building process works. Before photosynthetic bacteria transformed Earth’s atmosphere by filling it with oxygen, soil was nothing more than a mineral mixture of anoxic green clay. After oxygen entered the atmosphere, minerals started reacting with the oxygen, and red iron oxides appeared in the soil. Good organic, rich, productive soils developed slowly only after algae and arthropods crawled from the sea to dry land and plants took root. Life colonized land and began shedding its wasted, used up and discarded parts onto the earth where they formed a carbon-rich banquet that allowed new life to feed and grow, using photosynthesis to pump ever more energy into the system.

Soil building is the product of a self-reinforcing, positive feedback loop. But soil decline is also a self-reinforcing loop that can result in catastrophic soil loss. Most forms of agriculture tend to deplete soil carbon by reducing the amount of natural organic inputs from leaf and fruit fall as well as from woody debris as it is found in native ecosystems. However, modern, chemically-based agriculture depletes soil carbon much more drastically. Nitrogen fertilizers combined with tillage accelerate microbial respiration, burning up soil carbon faster than it is replaced. Due to the loss of organic carbon reservoirs, many soils have become nearly lifeless substrates that must be continually fed with irrigation water, mineral nutrients and pesticides to produce a crop. Although productive in the short term, this practice is not sustainable. Soil scientist Rattan Lal estimated that “Most agricultural soils have lost 25% to 75% of their original soil organic carbon (SOC) pool.”

Is it possible that biochar can substitute for some of this missing soil carbon? Some of the most productive and resilient soils in the world contain significant quantities of “natural” biochar. Nature makes megatons of biochar in the process of naturally occurring wildfires in forests. Prairie fires can also generate a lot of biochar. Tall grasses burn quick and hot. Close to the ground, however, where the roots start, air is excluded. So the base of the grasses will pyrolyze and not burn. This kind of natural charcoal is present in some of the most valuable agricultural soils in the world, such as the carbon-rich Chernozems of the Russian steppe and the Mollisols of the US Midwestern prairie states. Recently scientists have looked more closely at the Mollisols and found that they contain charcoal that is “structurally comparable to char in the Terra Preta soils and much more abundant than previously thought (40–50% of organic C).”

Biochar – the Electric Carbon Sponge

Figure 1. Eight allotropes of carbon:  a) Diamond, b) Graphite, c) Lonsdaleite,  d) C60 (Buckminsterfullerene or buckyball), e) C540, f) C70, g) Amorphous carbon, and h) single-walled carbon nanotube or buckytube. Design created by Michael Ströck from: en.wikipedia.org-Allotropes_of_carbon

Figure 1. Eight allotropes of carbon:
a) Diamond, b) Graphite, c) Lonsdaleite,
d) C60 (Buckminsterfullerene or buckyball), e) C540, f) C70, g) Amorphous carbon, and h) single-walled carbon nanotube or buckytube. Design created by Michael Ströck from: en.wikipedia.org-Allotropes_of_carbon

To understand biochar, we must first appreciate the role of soil carbon. Soil carbon comes in many forms and the terminology used to describe it can be confusing. There are two main pools of carbon — organic and inorganic. Organic forms can be further divided into “recalcitrant carbon” or that resistant to decay, like humus, and “labile carbon.” Labile carbon will be quickly consumed by soil organisms because it is both bioavailable (in the form of easily degraded compounds such as oils, sugars and alcohols) and physically accessible to microbes (not bound up with minerals). These labile compounds include hydrogen and oxygen in the form of hydrocarbons and carbohydrates. The organic carbon pool includes both the living bodies and the dead, decomposing bodies of bacteria, fungi, insects and worms, along with plant debris and manure. Inorganic carbon includes the carbonates such as limestone, and even though some life forms use carbonates to make their shells or skeletons, these compounds are still termed “inorganic”. The main distinction of the inorganic carbon pool, however, is that it does not fundamentally provide microbes with energy for feeding the soil building reactions.

Mineral carbon refers to carbon solids like diamond and graphite as well as the gases of carbon (CO2, CO and many others). There are numerous ways a carbon atom can be arranged in a solid which leads to different physical structures, which are called allotropes. Allotropes of mineral carbon, include diamond, graphite, graphene, buckyballs and carbon nanotubes (Figure 1).

So what is biochar then? Organic or mineral carbon? Actually biochar is a mixture of both, depending on the conditions of formation. But let’s first look at how biochar is produced. Biochar is made by heating biomass under the exclusion of air. This process is called pyrolysis, which includes the drying of the biomass and the subsequent release of flammable vapors. Technically this can be done by many different methods. Some methods use a retort, which is a closed vessel that is externally heated. Heat is transferred through the metal vessel and vapors pass out of a vent where they can be burned and help heat the retort. Gasification is another method that supplies enough air to burn the vapors, but prevents the complete combustion of the biomass material by excluding air from the charcoal zone, thus preserving the biochar. Many other methods of charcoal making exist that range from simple pit kilns to multi-million dollar machines producing energy in gas or liquid form from the vapors.

ompare terra preta with normal tropical soil From presentation by Steve Diver at April 2013 Resilient Farmer workshop http://www.slideshare.net/MauraMcDW/emimo-kcsa-resilient-farmer-april-2013

ompare terra preta with normal tropical soil
From presentation by Steve Diver at April 2013 Resilient Farmer workshop
http://www.slideshare.net/MauraMcDW/emimo-kcsa-resilient-farmer-april-2013

The resulting charcoal resembles a blackened, shrunken version of the original biomass. But it now has very little hydrogen and oxygen. Microscopically, it inherits much of the structure of the original biomass. The only difference is the material now has been converted from lignin, cellulose and hemicellulose to many of the allotropes of carbon shown above (Figure 1); however, you will not find any diamonds in biochar! What you will find is a collection of disjointed graphite crystals based on hexagonally-shaped carbon rings, with some leftover hydrogen and oxygen attached, along with minerals (ash) that were in the original feedstock. These hexagonal carbon compounds are fused carbon rings. Fused carbon rings are also called “aromatic” carbon, (another confusing chemistry term – it does not mean that the compound has a strong aroma, although some of them, like benzene, do. In chemistry it refers to the molecular structure containing a planar unsaturated ring of atoms that is stabilized by the bonds forming the ring.) They are very stable and it takes microbes a long time to degrade them. The more you heat the biomass, the more of these fused carbon rings are created. The rings hook up with each other to form layers and layers of discontinuous, rumpled sheets – the graphite crystals. Biochar’s jumble of carbon crystallites is an important source of its porosity – imagine all the tiny spaces in the wrinkles between sheets.

Biochar starts out as organic and becomes more mineral-like with heating. This mineral transformation creates the skeletal structure that looks like a carbon sponge (Figure 2). While the mineral, fused–carbon ring structure is hardly biodegradable, the recondensed vapors that can be found in the biochar pores and on its surfaces are less aromatic and more biodegradable and can thus be considered organic phases of the biochar.

The fused carbon rings are also responsible for the electrical activation of the biochar carbon sponge. Fused carbon rings form a special bond with each other that allows electrons to move around the molecule producing electrical properties like those that are found in engineered carbon materials such as graphene sheets and carbon nanotubes. Depending on the pyrolysis temperature and resulting arrangement of atoms, biochar can be an insulator, a semi-conductor or a conductor of electricity. Electrically active fused carbon rings also support “redox” or oxidation and reduction reactions that are important to soil biochemistry, by acting as both a source and sink of electrons. In soils, microorganisms use aromatic carbon both as an electron donor and as an electron acceptor during metabolic chemical reactions. Biochar seems to not only serve as an electron buffer for redox reactions, but it also helps bacteria swap electrons among themselves, improving their metabolic efficiency as a microbial community.

Terra Preta region -- Amazonian region of South America with terra preta soil sites shown as black circles, white circles indicate sites where there there are no terra preta soils Credit The Royal Society

Terra Preta region — Amazonian region of South America with terra preta soil sites shown as black circles, white circles indicate sites where there there are no terra preta soils
Credit The Royal Society

With its pores and its electrical charges, biochar is capable of both absorption and adsorption. Absorption (AB-sorption) is a function of pore volume. The larger pores absorb water, air and soluble nutrients like a normal sponge. Adsorption (AD-sorption) depends on surface area and charge. The surfaces of biochar, both internal and external, adsorb materials by electro-chemical bonds, working like an electric sponge.

Porosity comes in many scales, from the relatively large vascular and cellular structures preserved from the original biomass, to the nano-pores formed by tiny molecular dislocations. The amount of porosity depends mostly on the feedstock material, particle size, and the highest treatment temperature (HTT). Temperature determines how much of the volatiles (hydrogen and oxygen containing compounds) will be driven off and how much pure carbon graphite is formed. Generally, porosity increases as more volatiles are driven off, clearing the pores (although the pores can re-clog when vapors are incompletely driven off and condense on the forming biochar surfaces). Also, at temperatures approaching 1000 degrees C, pores begin to collapse or melt. For this reason, HTT is a key variable to know when specifying a biochar for a particular purpose. Porosity will also depend on the feedstock, with high ash feedstocks like grass reacting quite differently to heating than low ash feedstocks like wood or bamboo. For wood feedstocks, porosity typically peaks at an HTT of about 750 degrees C.

A Well-Aged Cheese

Biochar is not soil. The electric carbon sponge is only an ingredient in the mineral and organic stew that makes up soil. The dish is usually potluck, composed of whatever the local geology and biology provide. However the Terra Preta soils are different. The fertility of these black, humus-rich soils is many times greater than the surrounding, highly leached red soils. They may have been deliberately created over centuries by people living on densely settled high bluffs along the Amazon River. It is thought that the ingredients included charcoal, ash, food scraps and human excrements, but how they actually combined to form Terra Preta is unknown. Explaining the formation of the Terra Preta is like determining the recipe for a fine Camembert cheese. You can analyze all the ingredients and still have not the faintest idea how to make one if you don’t learn it from the artisans.

 

Figure 2. The skeletal structure of biochar looks like a carbon sponge.

Figure 2. The skeletal structure of biochar looks like a carbon sponge.

One thing that is becoming obvious after a decade of biochar scientific research and the first results from multi-year field trials is that, just like a good cheese, the time dimension is critical. From the moment that biochar is pulled from the kiln, its surfaces begin to oxidize and form new compounds. These changes result in different molecules attached to the surface, called “functional groups,” composed primarily of oxygen, hydrogen and carbon. The functional groups are able to bond with nutrients and minerals, while the underlying fused carbon rings support redox reactions (reactions that move electrons) and shuttle electrons around the microbial community attached to biochar surfaces, potentially enhancing microbial metabolism and the cycling of nutrients. The end result of this ferment could be any one of many “terroir”-distinct Terra Preta flavors, depending on what kind of soil, organic matter, minerals, water and life forms come into contact with the biochar, and how long it has to ripen. But, if you sample the cheese before it is mature, it’s just sour milk.

Raw biochar placed in soils before it has a chance to collect a charge of nutrients can actually reduce crop yields because 1) it reduces the availability of plant nutrients by binding and immobilizing them and/or 2) it may add volatile organic compounds (labile carbon) that feed a bloom of microbes that use up nitrogen in the soil, depriving plants. These problems are easily corrected by adding nutrients to the charcoal application to compensate for this effect. Once the labile carbon fraction is used up, biochar enters a new phase – a deep time dimension where its carbon matrix is stable for hundreds to thousands of years and may become the core of humic substances that crystalize around the fine biochar particles; at least this is what the existence of ancient fertile black earth soils suggests.

In fact, biochar, whether naturally created or man-made, may be the base of many humic materials found in soils (Hayes, 2013). Very little humus naturally forms in tropical soils, where high temperatures and moisture accelerate microbial decomposition, yet Terra Preta soils have a high content of humus. To understand why, scientists added new organic matter to both a Terra Preta soil and an adjacent, poor natural soil. They found that more of the organic matter was retained as stable humus in the Terra Preta soil. A combination of factors may lead to this result. Biochar surfaces adsorb carbon and retain it in compounds with minerals, supporting at the same time a large microbial community that potentially makes more efficient use of organic debris containing carbon and other nutrients. The existence of this mechanism raises the possibility that Terra Preta soils are thus able to accumulate additional carbon more efficiently than adjacent soils.

If tropical soils need biochar to make humus, what about compost? Well balanced compost, with the optimum C:N ratio, will contain lots of humus. However, if there is not enough stable carbon (from wood, straw or other lignin sources), then the easily degradable sugars, fats and proteins will be completely consumed by microbes leaving very little substrate behind. This is what happens in tropical soils where heat, moisture and high microbial activity will decompose a fallen leaf nearly as soon as it hits the ground, allowing very little soil to form.

A number of studies have demonstrated that biochar has value as an ingredient in compost that can help capture nutrients and form humus. In the next section, we review some of these results and explain why biochar is valuable in compost. The answers will also tell us a lot about how biochar behaves in soil, because compost accelerates many of the processes that occur in healthy soil.

Kickstarting Compost with Biochar

If you look at a list of things biochar is supposed to do in soil, you’ll find it is very similar to lists you see for compost. Both biochar and compost are said to provide these benefits, taken from various claims made by biochar and compost manufacturers:
• Improves tilth and reduces soil bulk density
• Increases soil water holding capacity
• Becomes more stable by combining with clay minerals
• Increases cation exchange capacity (CEC – the ability to hold onto and transfer nutrient cations: ammonium, calcium, magnesium, and potassium)
• Improves fertilizer utilization, by reducing leaching from the root zone
• Retains minerals in plant available form
• Supports soil microbial life and biodiversity
• Helps plants resist diseases and pathogens
• Helps plants grow better in high salt situations
• Adds humus carbon to the soil carbon pool, reducing the atmospheric carbon pool

If compost really can do all these things, why do we need biochar? The answer is twofold:

First, unlike biochar, compost is quickly broken down by microbial action in soil over months to at most, decades, depending primarily on climate. Biochar lasts at least ten times longer in most soils. Recently, I called a California agriculture extension agent with a question about adding compost to fields to improve water holding capacity. I was told that because of the hot climate, at least two applications a year are needed to maintain enough soil organic matter to make a difference in water holding capacity. Aside from the expense of applying that much compost, there is simply not enough compost available to support such large application rates.

Second, biochar has important synergistic effects when added to compost. Researchers find that biochar makes faster, more nutrient rich, more biologically diverse and more humified, stable compost. Below, I examine several of the most important biochar effects and summarize some recent research results.

1. Biochar keeps compost moist and aerated, promoting increased biological activity.

The composting process is governed by various physical parameters that are subject to alteration by the addition of biochar materials as bulking agents. Some of the parameters that most affect compost are: aeration, moisture content, temperature, bulk density, pH, electron buffering and the sorptive capacity of bulking agents. Water and air are both held in biochar pore spaces and voids, and the spaces between particles. Moisture is also the vehicle for bringing dissolved organic carbon, nitrogen and other plant nutritive compounds into contact with biochar surfaces where they can be captured. Biochar’s stable carbon matrix accepts electrons from decomposing organic compounds, buffering electric charges that might otherwise impair microbial activity and be responsible for the production of greenhouse gases like methane and hydrogen sulfides.

All these properties of biochar promote microbial activity in compost. Researchers tested 5% and 20% additions of pine chip biochar to poultry litter compost and found that the addition of 20% biochar caused microbial respiration (measured as CO2 emissions) to peak earlier and at a higher level than either the 5% or 0% biochar treatments.

2. Biochar increases nitrogen retention

When nitrogen-containing biomass materials decay, they can release large amounts of ammonia. Ammonium (NH4+) is the aqueous ion of ammonia. Ammonium is generated by microbial processes and nutrient cascades that convert nitrogen from organic forms found mainly in proteins and nucleic acids into mineral forms (ammonium, nitrate and nitrite) that can intermittently be converted by nitrifying and denitrifying microbes to gaseous emissions that include volatile ammonia gas (NH3), nitrogen gas (N2), nitrous oxide (N2O) and other reactive nitrogen gases (amines and indoles). At neutral pH the aqueous ammonium (NH4+) and the gaseous ammonia (NH3) are in equilibrium. Higher pH forces more of the aqueous ammonium into the gas phase that can escape to the atmosphere.

Numerous studies have shown that biochar is effective at retaining nitrogen in soils. Several studies have also shown that biochar enhances nitrogen retention in compost, reducing emissions of ammonia and increasing total nitrogen retention by as much as 65%. The ammonia retention ability of biochar can actually improve during the composting process. Adding 9% bamboo charcoal to sewage sludge compost tested sorption of ammonia on biochar during composting and found that while ammonia retention was correlated with saturation of binding sites in fresh bamboo biochar, this did not hold for composted bamboo biochar. During composting the biochar is subjected to an accelerated aging process. That means that biochar surfaces get oxidized and enriched by carboxylic (acid) functional groups. The latter more than doubled at the end of the composting period, improving the capacity to exchange cations like ammonia.

3. Biochar improves compost maturity and humic content

Several studies have looked at effects of biochar on the timing and results of compost maturation and found that adding biochar to compost reduced the amount of dissolved organic carbon (labile carbon) in mature compost while increasing the fraction of stable humic materials (stable carbon).

4. Biochar compost improves plant growth

Biochar seems to improve the composting process, but how do plants like those biochar-composts? Several researchers have experimented with various combinations of compost and biochar added as separate amendments. These studies found improved plant growth response when biochar was added to soil along with compost. A 2013 study in Germany looked instead at biochar composted together with other materials. It tested six different amounts of biochar in compost, from 0 to 50% by weight, and also three different application rates of each compost type. Using oats in greenhouse pots on two different substrates (sandy soil and loamy soil), researchers found that plant growth increased with increasing application rates of each type of biochar compost, which is not surprising since the amount of deliverable nutrients was increased, at least by the compost fraction. They also discovered, however, that plant growth was increased as the amount of biochar in the compost increased. The biochar may either have improved nutrient retention during the composting process with subsequent enhancement of nutrient delivery to plants, or it promoted plant growth through some other mechanism. However, the researchers confirmed that synergistic effects can be achieved by adding biochar to composts.

How could we put biochar to work in soils?

One of the basic principles of good compost production is that the wider the variety of materials you use, the better the compost. The ideal biochar compost system is based on a speculative reconstruction of the Terra Preta soils. According to this model, these areas began as garbage dumps where accumulation of food wastes, ashes and manure were deposited. However, as populations grew, it is possible that they began to realize that the waste sites were developing into very fertile and productive areas. They may have begun to deliberately manage the material flows of plant biomass, mammal and fish bones, ash, biochar, and human excreta that likely resulted in the Terra Preta soils we see today.

For maximum conservation of resources, it is important to remember another principle: use the less degradable carbon sources like biochar to help preserve the more easily degradable but nutrient-laden sources like manure and food waste. I believe there is much exciting work ahead to determine optimum recipes for biochar-based organic composts and ferments, exploring the effects of different kinds of biochar in combination with other compost ingredients.

From past and on-going research, we realize that biochar has numerous possible mechanisms for its action in soils that can occur on a variety of different scales. But if the results from recent biochar compost research prove to be consistent, we now have the beginnings of a recipe book for biochar-enhanced super compost that can kickstart the process of returning carbon to soils today. Our industrial legacy has left us with a rapidly deteriorating climate, and soils that are dying and eroding. Biochar, as a form of recalcitrant carbon, may be just the medicine that degraded and unproductive soils need.

Kelpie Wilson is a writer and a mechanical engineer who has worked in the biochar field since 2007. She was a project developer and writer for the International Biochar Initiative (from 2008-2012) and now works as editor of the Biochar Journal and with her company Wilson Biochar Associates. She has been a tree hugger, an auto mechanic and a science fiction author, and has lived off-grid in the Oregon woods since 1990. Have a look at her valuable backyard biochar website with many low budget biochar production devices developed by Kelpie & others.




The Truth About Ruminants and Methane

The role of ruminants in reducing agriculture’s carbon footprint in North America

This 9-page paper by W. Richard Teague, Steve Apfelbaum, Rattan Lal, Urs P. Kreuter, Jason Rowntree, Christian A. Davies, Russ Conser, Mark Rasmussen, Jerry Hatfield, Tong Wang, Fugul Wang, and Peter Byck was published in the March/April 2016 Journal of Soil and Water Conserva-tion, vol. 70, no. 2, page 156

Summary: This scientific paper argues that the co-evolution of grass and ruminant grazers over the last 40 million years resulted in organisms capable of sequestering large amounts of atmospheric carbon in grassland soils. When measured in greenhouse gas (GHG) units, their sequestration exceeded GHG emissions (including emissions of methane) caused by these grazers, resulting in net soil carbon gains.

Argument: The authors collected data from peer-reviewed studies to compare global GHG emissions from the 3 main agricultural sources: raising domes-tic livestock (primarily ruminants), crop production (including tillage, fertilization, harvest and transport) and soil erosion (from both livestock and crop operations). They also evaluated methods of managing ruminants to increase carbon sequestration in soil.

The authors found that, properly managed, ruminant grazing can sequester more GHGs than it emits. Such good management, here referred to as regen-erative adaptive multipaddock (AMP) conservation grazing, uses short periods of grazing in an area before the animals move to new feeding grounds, leaving old areas to experience extended periods of recovery after being grazed.

In prehistoric times before conscious human management, such short grazing periods were enforced on large migratory ruminant herds by their desire to avoid heavily fouled grazing sites and to respond to predation, fire, herding and hunting. Today, the AMP rancher constantly and proactively adjusts the grazing period to the amount of forage remaining, calculating the needed recovery period given the season, rainfall and other conditions.
When properly managed, this system results in soil microbes rapidly recycling nutrients and enhancing the soil structure to result in increased soil carbon levels.

The below figure shows the authors’ calculations of net North American greenhouse gas emissions for 5 agricultural scenarios. All 5 scenarios assume cur-rent conventional crop production methods and yields, resulting in the annual emission of 0.083 gigatons of carbon (Gt/C — blue component of each bar in graph).

The livestock-raising components of each scenario differ, however. Scenario 1 shows current quantities of animals and methods. Scenario 2 cuts animal quantities by 50%, but assumes current production methods. Scenarios 3 through 5 involve current animal quantities, but assume increasing percentages of those animals are raised using AMP grazing: 25% in scenario 3, 50% in scenario 4, and 100% in scenario 5. Thus emissions from soil erosion (red por-tion of each bar) decrease as AMP methods are increasingly used (scenarios 3 to 5). The final component of GHG emissions (green portion of each bar) is those from the livestock themselves. Without AMP grazing, GHG emissions (primarily methane) are positive, although scenario 2 results in half the emis-sions of scenario 1 since livestock numbers are cut by 50%. As AMP grazing is increased (scenarios 3 to 5), however, carbon becomes sequestered in soil and net livestock GHG emissions (green portion of bar) go negative. In scenarios 4 and 5 overall emissions are negative because more greenhouse gases are sequestered than emitted.




Farming with Animals, Cover Crops, Manure, Mulches, and Minimal Tillage

photo by Jack Kittredge
Julie Rawson in West Field at Many Hands Organic Farm, admiring some kale and broccoli

Central Massachusetts is not what you would call prime farmland. Like most of New England that isn’t blessed with a nearby waterway and thus alluvial deposits, our soils are thin and only farmable where the underlying landforms aren’t too rocky, hilly or wet to grow crops.

When Julie and I bought this land 36 years ago it was composed of two played-out hayfields that had been de-rocked years ago and about 30 acres of woods that had not. Since then we have put drain tile under the fields to get them plantable by April, brought or grown onto them uncountable tons of organic matter to build soil, and hauled from them an equal volume of rocks that the first team of de-rockers somehow missed. We have yet to deal with the underlying abundance of potter’s clay and ledge.

The big advantage to central Massachusetts, we told ourselves, was that the land was so unattractive to farmers that we didn’t have to worry about spray drift or chemical contamination by neighbors, a huge concern where Julie grew up in Illinois.

Since then we have built a serviceable farm here, certified organic since 1987 and are providing produce and small and orchard fruit through a CSA to some 60 families currently, and to several wholesale accounts. We also raise a number of animals and sell meat and eggs, mostly to individuals.

Soil Fertility

photo by Jack Kittredge
Perennial weeds ferment in water which is then added to the nutrient drench delivered to crops by drip irrigation

As in raising our children, one of the most important concerns for Julie (the primary farmer) has been providing adequate nutrition. That has only gotten stronger over the years. For the last ten years she has been taking a fall soil test (she feels that laboratories like Logan Labs, which use the protocols de-veloped by William Albrecht, are the gold standard for soil testing) and using that as the basis for what to put down the next year. She consults with our son Dan to better understand the test and make recommendations based upon it.

But Rawson does not rely on purchased products for all of her inputs – she also tries ideas picked up from other farmers. At a recent conference Maine’s Mark Fulford suggested using water from fermented weeds as an activator. Julie is trying this out and leads me to her many pails stuffed with plants soaking in brownish water.

“These are all kinds of perennial weeds – whatever is green that we can find. They start fermenting when you soak them, which we do for a week or so, till they get really stinky, then we use the water in the foliar spray mix that we apply to our plants. It makes them grow faster. We can use what is left of the weeds for compost.”

Livestock and Crop Symbiosis

One of the traits which distinguishes our farm from many area organic farms is the presence of a significant number of livestock and poultry. Besides lik-ing to eat meat and eggs that we know are from humanely raised and healthily fed creatures, Julie believes in integrating plants and animals in much the same way that nature does.

“One of the things that we have been trying to perfect,” she explains, “is how to best utilize the animals we have here — we raise 300 meat chickens a year plus adding a hundred new layers each year. We also have two cows, 9 pigs and up to a hundred turkeys.

“What we’re trying to do,” she continues, “is better use the animals in the vegetable growing areas. Before, when the certification standards required 60 days between the removal of animals and harvest of vegetables, we were able to do more with animals right there in the field. Now that they require most-ly 120 days for any crop that has edible parts that touch the ground, we have to be more creative. Chickens can destroy an area, as can pigs. But I try to bring our animals through the vegetable areas when we can, and balance the issue of wanting to have something growing there when they leave. I want to have as much green growing in wintertime as I can so I want those chickens coming in on an area that has perennial cover crops or going through an area early enough that you can plant cover crops after them. That is one of the real challenges of managing animals in this system.”

When putting animals on a field Rawson tries to replicate the ideas that have been popularized by Alan Savory concerning intensive but short periods of grazing followed by rest to allow the pasture to regrow, often called ‘mobstocking’.

“We have found that really builds the structure of the soil,” she stresses. “This summer, when we were in drought, our hayfield was bright green and still growing. We have plenty of pasture right now in mid-October although a lot of folks are struggling with not having enough green in their fields.”

The West Field Experience

photo by Jack Kittredge
Clover grows in the pathways and under the kale

In 2015, for the first time ever, Rawson took one of the main vegetable growing areas out of production in order to fully bring in the benefits of livestock and poultry and long term cover crops.

“We have about three acres of vegetable land,” she explains, “and in 2014 we put down a cover crop on a half acre we call ‘the West Field’ and later put our two beef cows on it to eat it down. They stayed there all winter and we took them out in the spring of 2015, let it all grow back, and put the steers back in again so they were pasturing there in July. Then we put our turkeys, who are out on pasture August to November, on it. They moved back and forth on that field a couple of times. Finally, we covered the entire half acre in cardboard and covered it with leaves, hay and wood chips.”

The results of Julie’s planned ‘Rest & Rehabilitation’ for the West Field have been more than she hoped for.

“Generally this field has been a real paradise this year,” she asserts. “It continues to produce an amazing quantity and quality of food. Just yesterday (October 10) this 100-foot bed of Ace peppers produced 50 pounds for us. The kale, which was planted in April, we are still harvesting. It was a superb crop. This has been a real paradise for broccoli. You can see the blueness of the plants. With broccoli generally you get a head and some side shoots and then the plant piddles out. In the West Field they are producing tertiary heads!”

This last year, because of her concern about carbon and weather etremes, Julie has experimented with various ways of practicing little or no tillage. It is way too early for her to draw conclusions, but she thinks some of these methods show real promise and says the farming year was quite successful. Despite the worst drought central Massachusetts has experienced in our 34 years of growing, it was one of our most productive years. Both crop yield and crop quality were high.

Solarization

One of the methods of preparing a seed bed in a planting area without tillage that has worked for Julie is to ‘solarize’ it. Solarization is the coverage of a growing area with a sheet of greenhouse plastic for long enough (it depends on the time of year, with longer times being necessary in spring and fall and shorter ones in summer) to kill vegetative growth in the top half inch or so of soil without bothering soil life any deeper. In summer this process can be accomplished in one 24-hour period,

“We planted cover crops last fall,” she relates, showing me some beds of thriving kale plants, “in the vegetable crops that were here and mowed them down in mid-June this year. We took the hay off and solarized these beds. Then we took our partially composted woodchips that we got from the local DPW and laid them down. Then we planted kale seedlings on June 22 through the wood chips — we just dug a hole with our hands and put the kale in — and then laid down the drip tape. We didn’t bother with the fungal inoculants that we often use because we figured we had lots of fungus from the wood chips.”

Wood Chips

Wood chips are one of the major innovations Rawson introduced to the farm this year. Our local Department of Public Works collects them from land-scapers and makes them available gratis, loaded into your pickup, to anyone in town who can use them. Julie hired a dump truck and we ended up taking 13 loads this spring. She finds that they are excellent as a mulch and can be applied for many crops even before planting.

“We tried planting through cardboard and wood chips this year,” she explains. “When we planted transplants, we used string to mark our beds and pathways and just dug a hole in the bed through the chips and planted our tomatoes or brassicas. In one instance we planted cucumbers and carrot, seeds in beds that had been mulched with chips for an earlier crop of onions. We drew a pathway and shallow furrow through the chips -– probably an inch deep — with a hoe and planted the seeds in that and covered them back up with dirt. There was a challenge with wood chips falling into the furrow until we learned how far to pull them back – probably 3 inches or so for cucumber seeds. If we are doing something like carrots, however, which we do as 4 rows equidistant in the bed, we found retrospectively that it was better to rake all the chips off the bed first. Germination was not good when we didn’t completely remove them from the bed.

“I have limited experience so far in all this,” Rawson admits, “but I have plenty of experience in evaluating crops and know we got an excellent response from plants sitting there in that wood mulch. For some crops that we planted with a more conventional preparation using the tiller, we weeded once and then mulched the beds heavily with chips. The dirt under there is really friable. There is a lot of fungal activity going on – you can see the white threads of fungus in the soil. Some of my take-homes for this year are that using wood chips as a mulch on crops that are prone to having weed problems has been a real labor saver for us and also has created some really high quality crops. We used this system with onions, leeks, carrots, parsley. One of the things we learned is that, even though many people are concerned about wood chips because they think too much carbon will tie up nitrogen in the soil, when you have carbon covering on the soil it can break down slowly. Worms and microbial life will access it as needed. They will keep the carbon:nitrogen ratio in balance if you don’t incorporate the carbonaceous material in the soil but leave it on top.”

Cardboard

Another innovation we tried was massive coverage of soil in the fall with cardboard. Julie and I located the merchants in town last year who went through large amounts of big corrugated boxes (think dealers of motor cycles, stoves, refrigerators, replacement windows and doors) received their blessings for scheduled raids upon their dumpsters, and brought home truckloads of the stuff which were then laid out over one-half of an acre of field from November through March. On top of that we would often pile truckloads of oak leaves just scavenged from edges of the scenic, tree-lined road on which we live.

“That was the preparation we used in the West field”, she points out. “Just before slaughter of our turkeys in 2015 we started laying down cardboard on the veggie portion of that field (the sunniest portion, in the center of the field). We covered that cardboard with whatever we could – some hay, oak leaves from the roads, and finally wood chips we got from the DPW. Essentially there was cardboard everywhere, covered with a lot of carbonaceous, natural materials.”

The cardboard didn’t break down over the winter and spring as much as Julie hoped, in part because of the lack of precipitation.

“I was worried early on with the cardboard,” she recalls, “that it didn’t seem like the soil was going to be soft and deep.”

Although she mostly planted through the cardboard, in one section of the field she pulled off the cardboard and hay, poked holes every 18 to 24 inches, and planted transplants into the dirt. But she didn’t till. She recalls that worms just filled the area under the carqboard, lying side by side.

“I felt a clodiness to the soil,” she says, “that reminded me of growing up in Illinois — clods the size of my hand, cracks in the soil. It was a different struc-ture than I’m used to here. I finally realized after talking to NRCS people that those clods are a good thing. That bore out in the crops we got here. What I noticed when we planted things here is that they immediately took off, they were dark, beautiful green from the start. That was the second week in June.

“Cardboard works very well to attract earthworms into the system,” she asserts. “I’m not sure why – they must be eating the cardboard or microbes are doing that and the worms are eating them. Also you can see daikon here and there. These are nicely formed plants that have a cohesive structure. The soybeans here were meaty, the summer squash quality and consistency was strong and resulted in a huge amount of production for a long period of time. I’d never had that kind of consistency. Things last longer when raised this way. Here are tomatoes that we didn’t pick last night. Looks like these made it through the frost. These were mammoth plants and we didn’t start getting early blight until about the fourth week in September.

“What I have found where we were just using cardboard,” she continues, “is that the plants, albeit planted earlier, when they came up they had these monster frames. Broccoli are still pumping out heads -– tertiary heads bigger than the primary heads across the street. The cabbages were monstrous too. What I have found this year is that the crops which were planted in that field have much more staying power that the crops planted elsewhere, which did pretty well, actually. With a second crop going in, or at the end of their life cycle, the other crops started to peter out, which I thought was pretty natural for mid October. But I am finding that in the cardboard-treated field the kale is still going strong, the pepper plants, broccoli, cabbages all have a frame that is two to four times the size of those elsewhere and are more resilient.”

Despite all these wonders, Julie is not planning on laying out massive amounts of cardboard this winter.

“It was a lot of work,” she says. “It is a good activity for a winter that is totally open and has little snow, and I will continue to use it around open peren-nials like blueberries, red raspberries, black raspberries, rhubarb – things where you want to have it clean right under the branches so weeds don’t grow too heavily there. In 2016 we used a lot on perennials and put wood chips on top. We had green pathways between the rows that were mowable!”

Avoiding Tillage

photo by Jack Kittredge
Cows and chickens are moved daily, with the birds closely following the bovines. Here Julie and grandson Sammy tend to the animal chores

One interesting lesson so far that Rawson is taking to heart is that despite all her fertility amendments and other good management practices, although her first crop in an area does well, replants in a bed that has been tilled do not hold that quality for the next crop.

“This kale,” she says, pointing out a bed of it “comes from an area that we tilled before we planted lettuce in the spring. After the lettuce came out we put the kale in. The planting was similarly timed to the kale across the street. You can see the difference in quality. These beds were tilled in the spring and got our usual treatment of fertility, drenching and so forth. The lettuce we harvested earlier out of here was very nice and we brought more wood chips in and did a similar treatment and planting to what we did to the other kale. We even under-sowed clover. The big difference is that in the first beds we looked at there has been no tillage since the spring of last year. This one was tilled this spring. Also this is a second crop, a succession where that was the first crop after a cover. This bed is full of grass that maybe came in through tillage. I don’t think the grass is hurting the kale, but the kale doesn’t look as good.”

“When I till and use all the good fertility practices I do,” Rawson explains, “I will have a good first crop but it can’t sustain it for a second crop. Some-times we plant after cardboard, sometimes after cover crops, sometimes after cardboard and cover crops. But it is the tilling that makes the difference, leading to lesser plants. My surmise is that the tillage has a strong negative impact.”

Julie is not sure why areas that have been no-tilled look so much better, but figures that those that have been tilled don’t have as much microbial activity in the soil, particularly less fungal activity.

A major problem that no-till presents is having to change the way you plant. That is part of the work that Many Hands Organic Farm is hoping to address next year.

“We are trying to find creative ways to plant into old cover crop residues,” Rawson says. “That is where our new learning is heading next year. How can we learn how to plant small seeded crops without having to till first? We want to use Bryan O’Hara methods, but that requires a lot of compost and we don’t yet have that system in place.”
Cover Crops

photo by Jack Kittredge
These brassicas were planted without tillage into our West Field, covered over last winter in cardboard and mulched with wood chips.

Besides reducing tillage, the other carbon-building practice Julie has had a lot of success with is use of cocktail cover crops. Although 2016 was a bad year for drought and cover crops sometimes had difficulty germinating, their use seemed to augment crop production.

“We planted cucumbers in our small hoophouse in the spring,” she says. “When they were up adequately we broadcast an annual cover crop mix. The cucumbers were mulched with hay and woodchips and the annual cover crop mix was broadcast onto the mulch. The cucumbers that were here had the longest life of any of our cucumbers on the farm.

“Kale was slow to start,” she continues, “but once it was six inches tall we undersowed clover in the bed to get more greenery in there. We put down some worm castings but not much — a 5 gallon pail of them on a bed 4 feet wide and 130 feet long. You can see they are generally darker and more vibrant than the ones that followed the lettuce crop. What I see is a better building of frame. That is what you want.”

Julie’s interest in cover crops resulted in MHOF being the site of a cover crop workshop attended by 50 or 60 people on July 25. She had taken a section of a field and planted it to 3, 6, 9, 12, 15 and 18-way cover crop mixes. Ray Archuleta and Brandon Smith came from NRCS, dug up soil samples, and showed attendees how to evaluate them. Ray was particularly pleased with our level of soil aggregation!

The biggest problem with cover crop use in operations that specialize in annual vegetable crops is getting them to go away when their usefulness is done. Unless carefully managed, perennial cover crops can overwhelm and crowd out crops planted into them.

The primary ways cover crops are disabled without tillage are by winter killing (for annuals), by rolling over them with a heavy tractor-drawn ‘roll-er-crimper’ which is supposed to knock them down and crimp their stems so that sap can no longer flow up and down, effectively killing them, or by mowing. The latter two systems are far more effective if the cover crop is at the ‘milk stage’ where its energy has shifted from vegetative growth to seed growth. That way the plant is less likely to have the strength to repair damage inflicted by crimping or mowing which does not succeed in actually killing the plant. The risk, however, is that unless done in a timely manner, the plant will get to the stage of setting seed, after which any practical management method guarantees widespread unwanted seed distribution — likely to lead to serious problems when the seed comes up.

“Some people talk about crimping the cover crop and then planting right into that,” she says. “But we haven’t done that and I don’t know what tools could be used for that. I’m using what tools we have available to us. My understanding is that it is very difficult to kill rye unless it is ready to die! My so-lution for early crops is to plant where we have used cardboard, or use annual cover crops that will winterkill.

“Vetch is another killer,” she continues, “like rye. It wraps around everything and chokes it to death where rye just muscles it out. But I like them because vetch fixes nitrogen and rye mines for minerals and builds incredible soil structure with its long roots. You can use nitrogen-fixing annuals like Austrian winter peas and many of the clovers in winter-kill cover mixes, but I like the soil building effect of the perennials so I’ll still use a lot of them.

“If I plant perennial cover crops like rye and vetch,” she concludes, “which are the major aggressive ones I have used here, I have to be sure that the crops I want to plant there the next year are not early crops. You can maybe push it for us, in cold central Mass, if you are planning to plant something on June 1 you could raise rye there, maybe even June 15, and be assured that when you mow it and knock it down it is done growing. That will be the milk stage when all the energy is going into seed production and the stalks become brittle and it loses its vegetative strength. At that moment you can take it out and it won’t grow back. We don’t have a roller crimper to crush the cover crop, so what we do is mow it with a rotary mower. In some areas we did till in 2016 because we had put in rye for the winter and it was hard to kill in the spring. We wanted to use that soil when it was too early for the rye to reach its milk stage — when we could mow it and kill it.

Her experiences with cover crops this year have taught Rawson a lot about management strategies. She feels next year she will be able to manage a lot better.
“Next year,” she promises, “we will have certain areas that were planted into annual cover crops in 2016 that will be the first places we plant. We’ll leave the other areas until June 10 or so and knock down the perennial cover crops and plant into them. But we will cover crop everywhere!”

Green Pathways

photo by Jack Kittredge
These Copra onions, one of our best crops ever, were planted as seedlings into a wood chip mulch after using broadforking of winter-killed cover crops as bed preparation.

Julie is careful to maintain green, carbon producing pathways between her cropping beds. Generally she prefers clover for that purpose, because it doesn’t get too tall and as a legume fixes nitrogen from the atmosphere into the soil. There are some tricky issues in keeping pathways properly managed, howev-er.

Especially with annual beds,” she says, “we make all the pathways 20 inches wide so we can mow them with a hand mower. Part of the problem of mowing pathways with vegetable crops, of course, is that the crops get big and it is hard to do. But if the crop in the bed has big leaves that hang into the pathway, just push them aside as needed to mow.”

Rawson takes us to a pathway between a kale bed and a parsley bed. The kale is tall enough to shade the pathway, and when they harvest the parsley weeders go in advance of the cutters to ‘weed’ the pathway where it comes up to and over the edge of the parsley bed.

“Maybe you don’t keep mowing once the vegetables themselves are drooping over the edges,” she agrees. “But at that point it isn’t so much an issue and the crops are shading the path and growth has slowed down late in the season. It is a work in progress, not always neat. There are certain things you don’t want to do, however, like mow lettuce pathways where you are shooting the grass onto the lettuce. You maybe use a bagger or don’t mow when you are near harvest.”

She also uses green pathways between rows of perennials like rhubarb. Julie mulches the rhubarb itself with wood chips and old chicken bedding, and then lets the middle of the pathway grow up in grass that can be mowed.

Undersowing

photo by Jack Kittredge
Lettuces are transplanted into a wood chip compost, in spots marked off by a 4’ x 4’ dibble, being pressed into bed in upper right. Note drip irrigation header in foreground. Bed prep included mowing and removing perennial cover crops in mid-June followed by one day of solarization. Outstanding high quality lettuce was harvested throughout July in 100˚ heat.

Clover is also excellent undersown with tall crops like kale or chard. In one bed Julie planted chard in May, mulched it with cover crop residue, then broadcast clover on top of that mulch. In October she is still harvesting the chard, which has a lot of good color and taste.

“The Chenopods do well with clover,” she asserts. “I use crimson red. The crimson clover doesn’t necessarily come back next spring. I’d rather not have it come back when I’m planting new crops. The clover can overwhelm them when young. In the pathway is Dutch white clover. That is more of a perennial clover. It can take a lot of traffic and will come back next year.”

Water Infiltration

Water is obviously crucial to agriculture. That importance was accentuated at MHOF in 2016 because of the drought impacting much of central Massa-chusetts. But Rawson feels that the water problems at the farm – both from too much and too little – have been mitigated by the years of building soil carbon.

“I’m very cognizant of the water penetration of our soil,” she says. “When we first moved here in 1982 it had been a hayfield and there was a lot of stand-ing water after any rain. It was a serious problem for us, particularly in June. We have slowly built up our soil structure for 34 years now through lots of good practices. The issue with water has gone away. I remember a rain in 2015 that was one of those 2 inches in an hour rains. The water percolated into the soil and was gone in 10 minutes! This year with a severe drought we had drip irrigation, but each bed would get just an hour or two once per week. Nevertheless, we had stellar crops throughout the whole season. They didn’t succumb to drought. I credit the water-holding capacity of our soil.”

Future Plans

photo by Jack Kittredge
Julie harvests summer squash from giant plants in no-tilled West Field.

Rawson is constantly looking at the root structure of her crops and the soil’s texture and color.

“I got into farming because I like to play in the dirt,” she laughs. “I’m thinking about soil all the time. I didn’t really understand aggregation until lately, but I think our aggregation is good. Our soil is greasy and satiny. I think that is appetizing and comes from a lot of glomalin, the soil protein that fungi create which holds aggregates together.”

“On much of our land the soil is not very deep,” she admits. “I think that is because of a plow pan or perhaps just ledge close to the surface. We are trying to think about tools to deal with that. After going to a talk by Mark Fulford, I’m considering a tool to go down and break it up. It has some sort of shank and you drive over the bed and rip right down the middle, maybe 8 to 12 inches deep. While you are there cutting into the plow pan or ledge, you drop into the furrow a liquid fertilizer with lots of inoculant and then plant potatoes. That way you get the microbial life down there giving everything a boost and then your potatoes don’t grow out and get green shoulders, either. They would partly grow down because there is a lot of space down there.”

Although mostly a practical farmer, Rawson is planning a small 4-way trial next year to compare various farming practices. She has selected an un-cropped area which has grown up with perennial grasses and weeds.

“We’re going to mow it and divide it into 4 equal sections,” she says. “The first one we’ll till this fall, and try to kill the sod, then come back and till 6 weeks later. Then we will leave it for the winter. Next spring we will plant a crop here. The second bed we will cover this fall with cardboard and put leaves and hay on top of that, and try to kill the sod that way. The third bed we will solarize in the spring and then plant into it. The last bed we are going to cover with tarps and kill by shading (called ‘occultation’). We will use the same fertility, same spacing, and plant the same crop in each area. We’ll measure yield and look at insect damage and weigh stuff and take pictures. I think it is important for anyone to be as curious and creative as they have time for. Bring systems that work into your protocols and be tinkering with them to get improvement.




IFOAM’s André Leu to Keynote NOFA Summer Conference:

André Leu, president of IFOAM, to keynote 2016 NOFA Summer Conference

André Leu, president of IFOAM, to keynote 2016 NOFA Summer Conference

André Leu is both a farmer and an advocate. With his family André operates a 150-acre fruit farm in tropical Australia. Once defeated and run down, his farm is now a lush and productive permaculture landscape, a system designed to minimize inputs and labor and maximize productivity, nutrient recycling and biodiversity.

For over 10 years he has been influencing international climate change policy, not only drawing attention to the role of soil in absorbing carbon to mitigate existing climate chaos, but also demonstrating how organic agriculture can help farmers and societies adapt to the effects of climate change. After the November 2015 Paris Climate Change Conference, he sees this as a critical time to galvanize nations to agree to include shifts in farming policies in their agreements and pledges and to see those pledges from idea to action.

International farming, education and market connectivity are important parts of his work, both as a farmer and educator, and also as the president of the board of directors of the International Federation of Organic Agriculture Movements (IFOAM) – Organics International.

André draws a clear connection between organic farming and a strong, viable, and sustainable path forward. “My message is one of hope. By changing farming we can reverse climate change and at the same time improve farms and make sure the world has a good future.” He is one of our two keynote speakers at the 2016 NOFA Summer Conference, August 12-14 in Amherst, MA. The other is farmer, educator and food justice activ-ist Leah Penniman.

His farm: “A regenerative agro-ecological system”
Leu comes from a farming family; his fondest childhood memories are times spent with his grandfather among their fruit trees. As a teen in the early 1970s he visited a pioneering organic farm in his native Australia with tropical fruits, flowers and vegetables. “For me, it was an incredible paradise. I’d just never seen anything like it. That was the moment when I said that’s what I want to do and the type of farming I want to do. I set about getting my first bit of land and that’s exactly what I do.”
Now André is on his third piece of land, which his family settled in the early 1990s. His farm is a high-yielding, low-input system, with yields equivalent to the best conventional growers in his area. Beyond just organic, Leu refers to his as a “regenerative agro-ecological sys-tem”. He will share many of the tips and techniques he utilizes on his own property, adapted for Northeast climates and ecosystems, in his Friday morning Intensive seminar, to be held on Friday, August 12.
“When you get the system up, a lot of the work in the farm now is done by the ecological system,” notes Leu. “It lowers the amount of work you have to do as a farmer since you don’t have to spray or anything like that.” On his property he focuses on mineral balancing, utilizing cover crops and perennials to manage weeds and provide organic matter and nutrients for the system, and providing habitat for beneficial insects to control pests and disease. He periodically strip mows areas of his land to get organic matter into the ground. Not wanting to eliminate beneficial habitat, he alternates rows, leaving mature ground cover as refuge and cutting it once the mowed area matures. He al-so boasts that he hasn’t had to spray organic approved pesticides for over seven years.

“I just love farm work,” says Leu. “Most people think I’m mad, but I regard it as a lovely mental holiday from what else I’m doing. Those of us who’ve chosen farming have a love of farming. The farmers will know what I’m talking about. The joy of being on the tractor is something only another farmer would understand.”

Climate Change: “We’ve got to get down and do the work”
Actively involved in setting climate change policy for over 10 years, André has participated in each United Nations climate meeting since Copenhagen in 2009. His message is this: We can reverse climate change through organic agriculture and we have the data to back up this assertion.

In November 2015, countries from across the world gathered to negotiate pledges of action to stem the tide of climate change at the Paris COP21 meeting. Leu was inside the negotiations, actively putting forward the benefits of organic agriculture for both climate change miti-gation and adaptation.

Together with his colleagues at Regeneration International, Leu is advocating for the ‘4 per 1000 Initiative’ put forward by the French government. The aim of the Initiative, according to website 4p1000.org, is to “demonstrate that agriculture, and agricultural soils in par-ticular, can play a crucial role where food security and climate change are concerned.” Essentially, the idea is with a sufficient increase in the amount of carbon stored in soils, it is possible to stop the increase in atmospheric carbon dioxide.

“At first we were lone voices,” states Leu, “but for us it is important that as the information got out more and more people have become interested — more and more organizations. By Paris the conversation had changed. For the first time the issue of soil carbon was a major part of the climate change talks.”

While the Paris agreement does not explicitly include agriculture to increase soil carbon, 28 of 195 countries that signed the Paris agree-ment have committed to increase levels of carbon stored in soils through agriculture. The countries include France, Mexico, Iran, Ukraine, Japan, and Canada, to name a few. “Where we are now is very encouraging and it’s a huge leap from where we started,” says Leu, “but there’s still a lot more work to be done to get the right language and to get these countries and their agriculture departments to understand that increasing soil carbon means a fundamental change in the way we do farming, grazing and agriculture. We have still got a long way to go. The fact that countries have committed towards this and started this process is to me very exciting.”

A gathering of parties will take place in Morocco in November of 2016. In the lead up to the gathering, organizations, nations and other actors are making presentations internationally to draw attention to the 4 per 1000 Initiative with the aim of securing strong action from nations that have agreed to partici-pate as well as get commitments from nations that have not yet joined the Initiative. “We have a document signed in Paris, but now we have to get down and do the work and make that document happen. Negotiating and signing a document is actually the easy part,” quips Leu. “The critical part now is to get people to actually do what they’ve signed. The real work starts now.”

Leu also points out that not only are the farming practices that encourage accumulation of soil carbon good for mitigating atmospheric carbon, they also “increase resilience and adaptation, the ability to capture and store water, to resist droughts, to resist damaging rains, the types of changes to climate that we’re seeing at the moment. It is equally important to be able to adapt as well as mitigate.”

International Work: “Out of poverty to relative prosperity…”

IFOAM Organics International is involved with a wide variety of projects, from helping small farmers build their crops and find markets to affecting pol-icy with governments and trade groups. Leu has been on the board of directors since 2008, serving as its president since 2011.

In places all over the world, IFOAM works with small family farmers to improve production systems. But more importantly in André’s view, the group also works to help farmers net the right price to be profitable. He provides the example of Uganda, where about 200,000 small family farmers have gone from abject poverty to having good food, health care, and the ability to send their children to school and university. He sees this work as helping “people get out of poverty to relative prosperity in their communities and turn their lives around through a combination of teaching better organic production techniques and getting paid a higher return for what they produce.”

Leu also trains farmers internationally himself, traveling extensively throughout Asia, the Middle East, the Americas and Europe. “My higher degrees are in adult education and training,” he shares. “I’ve worked with farm organizations for many years and still do. I like training farmers. That’s why I am happy to come to NOFA.”

André Leu and Leah Penniman keynote the 2016 NOFA Summer Conference, August 12-14 in Amherst, MA. Join us for three days of organic immer-sion, with 200 workshops to empower and educate, to build skills and confidence. Our children and teen conferences provide space for young people to cultivate their vision for an organic future. Before the conference begins, five intensive seminars will take place, including Regenerative Agriculture, Biodiversity, soil health & carbon sequestration, led by André Leu. Scholarships, work exchange and groups discounts are available. Find out more at www.nofasummerconference.org.