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Healthy Soil, Defined

What is healthy soil? Most farmers strive for a healthy, fer­tile soil that has good tilth. But do these terms — soil health, soil fertility and good tilth — all mean the same thing to all of us? I bet you have an image in your mind of what the soil and the crop grow­ing in it should look like. But in today’s

A worm comes up from the earth.

world, with all the available technology, plant protective fungicides, insecticides, etc. along with plenty of soluble nutri­ents, looking at a “good” crop can be deceiving. It may in fact be wearing a lot of ‘make-up,’ covering up its true state of health. In recent years, the USDA Natural Resources Conservation Service (NRCS) has started to focus more on soil health and what constitutes a “healthy” soil.

If we define soil health using the NRCS’ definition, it is “the capacity to function.” I thought about this definition for quite some time and decided I need­ed to add to it, clarifying the thought as “the capacity to function without inter­vention.” I define intervention as plant alterations, fungicides, insecticides, etc. Healthy soil should produce healthy crops without intervention.

Water infiltration and nutrient cy­cling are also part of the NRCS’ defini­tion of healthy soil. I believe that water infiltration is an aspect of soil tilth (wa­ter soaks in quicker in a loose, crumbly tilth soil). Soil fertility is defined as “the productivity of the land,” which would have a nutrient recycling component. Minerals are involved, too, not only in regards to volume but also balance. An exchange of nutrients throughout the growing season is what we are after. Adding nutrients can help supply and provide additional minerals to what the soil can supply to your crop, but are only a small part of what happens in total.

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The chemical test (soil nutrients), although of great value, cannot tell you what the land will produce, only what minerals it contains. So the question is how do we achieve “soil health?” Is it just getting the soil test looking perfect, then all will be perfect? Is it using the perfect compost or compost tea or biological additives and all else then works? How about just doing a diverse mix of green manure crops? What if we just quit till­age — then will it all fall into place?

Managing for soil health (improved soil function), says the NRCS, is mostly a matter of maintaining suitable habitat for the myriad of creatures that comprise the soil food web. As I’ve always said, it’s like making yogurt or baking a cake: get the ingredients, create the ideal space, and it will happen — but it does take time.

The NRCS publication on soil health further states that managing for soil health can be accomplished by disturb­ing the soil as little as possible, growing as many different species as is practical, keeping living plants in the soil as much as possible, and keeping the soil covered over all the time. That’s certainly all good advice, but it’s not everything. I’ve been at this a long time, and I do know that min­erals are essential. Start with a good soil and, at minimum, supply plant-available calcium, sulfur and boron. That’s assum­ing a lot of P and K has been supplied over the years and there are sufficient levels in the soil to grow a crop. Of course, there are more elements, but we do have to start somewhere. It can be really simple: soil test to find out what’s short or in excess and deal with it. Know that it takes time to make changes. How much to add has to do with getting a good crop. Be realistic with inputs and expectations.

Healthy Soil Questions

Along with soil correction, apply a balanced fertilizer that supplies many nutrients, in balance and in proportion for the crop you are growing. Again, where are you starting? What are your expectations?

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Do choose soil-and-plant root-friendly materials and add some carbon to buffer them. One method of adding nutrients that seems to be growing in popularity, makes sense and can save dollars while speeding up the process, is to add these nutrients for correction to the compost pile. Cook and brew them, then apply to the soil. Rock phosphates, gypsum, sulfur sources, and natural minerals all seem to fit well here.

Next, do your soil health program and crop fertilizer, and things should get bet­ter. “Earning the right” is a concept we teach: once soils are healthy, they need fewer chemicals and less commercial fer­tilizer, especially nitrogen. You can’t start right out on year one reducing these inputs, you have not earned the right to make that change. Adding the soil correc­tives with compost or growing a season of green manure crops — these are ways to start. In our part of the world, start with oats and peas in the spring, in June work them into the soil and plant buckwheat, then work that crop into the ground in fall and plant more oats with clover and rye grass. Next spring, when the clover and rye are a foot tall, work them in to the soil. (When I talk about working them in, I’m thinking shallow incorporation. If soil is tight and water won’t soak in, do an aggressive, deep, open-up tillage. The soil is alive and needs to breathe; it can’t be waterlogged or the aerobic soil life will certainly suffer. Opening up the soil will improve things.)

Now that’s a fast path to fixing soils. For organic farmers, there is a two crop-year land transition time — do your soil fixing and remineralization during those two years and you will no longer recognize the soils you started with! And you have now earned the right to reap the benefits of healthy soils with good tilth and high fertility. You’re off to a good start and the soils will keep get­ting better. And as this soil system keeps getting better and better, all that is left is to sustain it.

We can regenerate the soils, then sustain them so that the inputs and tech­nology needed by so many today will become obsolete. Remember, as you farm you are re­moving things from the soil. What needs to be replaced? What’s your objective? What are you managing for?

By Gary Zimmer, author of The Biological Farmer, 2nd Edition. This article was first published in the August 2012 issue of Acres U.S.A. magazine.

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