The Art of Balancing Soil Nutrients, A practical guide to interpreting soil tests

First of all, my perspective as reviewer: I am a gardener, farm volunteer, and student of soil science, who has attended soil workshops and organic farming conferences, and done her own independent reading and experimentation.

The subtitle is largely what this book accomplishes, written from “Crop Doc” McKibben’s decades of experience as a soil consultant in NW Ohio. The reader benefits from case studies of individual farms as well as comparisons across farms, over the course of a season or in many cases, several years. There are dozens of soil test reports reproduced in the book, each serving to demonstrate some point made in the text, so the reader necessarily becomes familiar and comfortable examining soil test reports.

In this book, McKibben’s experience and audience seem to be concentrated on row crops (corn, wheat, soybeans) or turf/golf course management. He addresses the challenges specific to each of these very different management situations fairly evenly over the course of the book, including not just the soil needs but also what is practical in each situation (e.g. a golf course manager typically applies amendments several times over the course of the season while an agricultural situation might have to make the most of the moment of pre-seeding, etc.)

The style of the book is somewhat conversational, less textbook-y, although each chapter is clearly and succinctly organized into sections, for instance going through each of the macronutrients and several of the more common trace elements, and their interactions with other nutrients. Within each section, though, it’s like he’s talking about a familiar personality and the conversational style kicks in. The paragraphs wander a bit and often jump from one bit of content to another. Often there is some flow, but I found myself flipping backwards and forwards to make connections, remind myself of what something was, or even find a definition of a term that is used early in the book but discussed much later. I also had to flip pages because often the text refers to a figure or table found several pages later in the book. I do appreciate that soil nutrition is a complicated subject with so many variables, interferences, etc., and that organizing the complex interactions along with the simple facts takes some clear decision-making about presentation. I found myself wishing for more of the information to be in chart form. There are a couple of handy charts he has created which I have not seen elsewhere.

McKibben explains and makes definite recommendations about the different types of crop and soil testing and timing of these, given your situation. He explains the shortcomings of each type and recommends more than one kind to get the full picture of what nutrients are actually available for use by the plants. He has correlated past soil test results and crop responses with hundreds of tissue analyses.

Cation exchange capacity is explained in fair detail including why and when you need to pay attention to that aspect of your soil test. He organizes soils into two tiers of total exchange capacity, low and high, giving each an entire chapter of special considerations. Even though you may have only one tier on your land, I would read both of these chapters as they cover different topics.

McKibben gives his commentary and analysis, and while speaking authoritatively, clearly states his opinion as his opinion and lets the reader in on his past mistakes. At the same time, he’ll make broad statements and conclusions that don’t jive with what I’ve heard recently from other soil experts. For instance, he repeatedly alerts us that the soil in no-till fields is almost always problematically stratified and compacted and thus puts limits on the roots and the soil nutrients they can access. He thus seems very much in favor of fairly heavy tillage when possible to ensure mixing of amendments and root access to nutrients. While these are no doubt very important to consider in many no-till situations, especially those that have been conventionally heavily fertilized and herbicided, McKibben does not mention the potential that no-till organic has to overcome these issues with the reach of fungi that might be able to thrive where there is no heavy tillage, for instance, and the resilient bounce/sponge quality and enhanced root growth possible in a well-aggregated soil.

Relevant to this, McKibben doesn’t cover a lot of ground with soil biology, hardly mentioning fungi and only briefly mentioning the role of soil bacteria in making nutrients available to plants. He also completely leaves soil biology out of his discussion of the limits to humus building and soil carbon sequestration. He goes through the calculations by which he arrived at his conclusion that one can not add 1% of soil organic matter to agricultural soils within a person’s lifetime. He maintains this conclusion even while acknowledging that it’s a very rough calculation—and even this acknowledgement shows no awareness of the role of the liquid carbon pathway that Christine Jones talks about (see the summer and fall issues of The Natural Farmer for more discussion of this.) At the same time, this conclusion leads him to emphatically instruct us to hold onto the organic matter we do have, calling it precious as gold.

Among other topics that receive considerable and repeated discussion are the role and quality of irrigation and the use of glyphosate (particularly its dangerous impact on micronutrients like manganese in the plant itself.)

This book can help shed much needed light on soil testing terminology and methods, and amendment use for those who are employing soil tests to help solve problems in agricultural or turf management situations. It covers many important topics, but not all, that must be understood by those who are serious about balancing the nutrients in soils on their farm, garden or landscape. I recommend it as part of a library that includes other resources about soil biology and about management techniques other than heavily tilled row-cropping and conventional turf management.