By Gary Zimmer and Leilani Zimmer Durand
My philosophy is that whatever you do on your farm should improve soil health. But how do you know what that is? The USDA defines soil health as, “The continued capacity of soil to function as a vital living ecosystem that sustains plants, animals and humans.” I would add to that definition and say that soil health isn’t just the capacity to function, it’s the capacity of soils to function without intervention.
What counts as “intervention?” Does intervention mean biotechnology, insecticides, fungicides and tillage? Is fertilizer an intervention? Do these interventions make your farm better for future years? I believe money spent on interventions needs to be shifted to inputs that yield soil health.
Appropriate intervention when absolutely needed is wise, but the goal is minimum intervention — in other words do everything you can to get the soils healthy and mineralized. Mineralize your soils using exchangeable nutrient sources that come from the carbon biological system. You have to create an ideal home for soil life and feed them in order to build soil health.
Remove the negatives, which include monoculture crops and excessive tillage. Reduce the use of other possible negatives added through harsh soluble fertilizers and excessive nitrogen, not to mention chemicals and biotechnology.
Farming for soil health means treating your farm like a system. For years we have been promoting the “rules” of biological farming (Six Principles of Biological Farming). Following these rules will lead to healthy soils that produce good yields. The soil health guidelines you now see published in many places focus on minimum disturbance with an emphasis on no-till. In my opinion not all soils are capable of being farmed no-till.
The Six Principles of Biological Farming
- Test and balance your soils, and in addition, feed the crop a balanced supplemented diet.
- Use fertilizers that do the least damage to soil life and plant roots. Watch salt and ammonia levels. Use a balance of soluble and slow-release nutrients for a controlled pH. Use homogenized micronutrients — add carbon — and place them properly to enhance performance.
- Use pesticides, herbicides, biotechnology and nitrogen in minimum amounts and only when absolutely necessary.
- Create maximum plant diversity by using green manure crops and tight rotations.
- Use tillage to control the decay of organic materials and to control soil air and water. Zone tillage, shallow incorporation of residues and deep tillage work great on many farms.
- Feed the soil life, using carbon from compost, green manures, livestock manures and crop residues. Apply calcium from a quality source in order to feed your crop and soil life.
I believe strip-till has its place on many farms as the strips create an ideal area where you can concentrate needed nutrient inputs and warm up our northern soils in order to grow large root systems. Some farms may also need to run deep rippers as compaction is a problem on many farms, and tight waterlogged soils are not healthy.
Regenerative farming is another philosophy of farming with a focus on soil health. Not just sustaining your soils but regenerating them makes sense, but this method of farming generally calls for cattle on every farm. Just like no-till doesn’t fit every farm, having cattle is not possible on every farm.
Cattle are desired for digestion — they eat the cover crops and digest them into plant nutrients in the form of manure. While this system can work well in northern climates where there is low rainfall and snow and frozen soils to minimize soil damage, how do you deal with waist-high cover crops in cold, wet, black soils? And what about all the compaction caused by those large animals stomping around, often in wet conditions?
I am a believer in growing cover crops and shallow incorporating the residues, using strip-till to get the right nutrients in the right place, with deep ripping to break up compaction. I believe on most farms some tillage is needed, but it’s the middle zone from 3-8 inches down with earthworm channels and old, dying roots that needs to be left alone. You don’t want to break up all your soil aggregates, fungal networks and homes for soil life, but you do want to till in order to digest residues and keep the soil loose and crumbly for air and water to infiltrate.
The more diversity of plants that you grow, the more types of root exudates to feed the soil life, and therefore the more diverse the soil biology and the less likely potential for large populations of trouble-causing insects and diseases. The plants determine the soil life so the more types of plants, the more diverse the biological life pool, and no one population takes control. Planting a diversity of crops and cover crops leads to healthy soils and healthy plants.
Minerals are also key for soil health and crop yields. There are at least 20 minerals known to grow healthy crops, and balance and ratio between those minerals is important, as is having a soil sufficiency level.
Trace elements are often overlooked, but are a key to plant health. Farmers often look for the direct yield increase for any added inputs on their farm, but what about the benefits gained from healthier plants that are able to resist pests and diseases?
Healthier plants lead to fewer interventions, which saves money and increases profits.
When applying fertilizer I like adding minerals in a carbon biological matrix. This is the way it’s done in nature. Plants, animals and soil biology all die with minerals tied to carbon in their bodies, and as they decompose they give those minerals up in a timed-release process.
For liquid carbon-based fertilizers I like to mix molasses or humic acids with the minerals. With dry fertilizers I like compost or digested manures. We use the manures from dairy farms that have gone through an anaerobic digester and then have minerals added to make blends that fit the farm’s needs. This anaerobic digestate and mineral blend has a large number of biological properties and dead bugs from the digester process that feed soil life and give up minerals in a plant-available form.
It’s also important to keep your soil life fed with the right kinds of food to maintain balance in the soil. I think of it as feeding the soil life like we feed our dairy cows. Any high-producing healthy dairy cow not only has a diversity of food in her diet but also has added minerals to maintain her health.
Her feed is a balance of soluble and slowly digestible food sources. You don’t get high production from feeding all mature, lignified plants because even though the cow may be healthy, production will be low as her rumen is spending a lot of time and energy doing the digesting. The same is true for soils.
Mature cover crops are slow to digest, which means they tie up nutrients and starve the crop while they’re breaking down. Young, green, knee-high diverse plant mixes will rapidly break down after they’re shallowly incorporated, providing soluble nutrients that feed soil bacteria and your crops for high yields.
As an organic farmer I have no choice but to take advantage of the nutrients released by working in a young cover crop if I want to grow high-yielding, nutrient-demanding crops like corn. Supplying nutrients for a good organic corn crop is like feeding a milk cow to get 100 pounds of milk per day — you need a lot of grain and other quickly digestible nutrients.
Growing legumes like soybeans is more like feeding your dry cow. You don’t need as many quickly available soluble nutrients, so you can use more mature plants that are slower-release nutrient sources.
When farming organically you have to get this system working perfectly or you need to do some interventions. Smaller amounts of high-quality fertilizers and nitrogen properly placed and timed provide extra quickly available nutrients to feed your crop.
Even though you can have really healthy soils by growing only mature cover crops and doing no-till and compost, you won’t get great yields following this practice.
Mature cover crops will build soil organic matter, but they do it by breaking down slowly and scavenging nitrogen, sulfur and other key nutrients from the soil.
Those nutrients will eventually be released back into the soil, but it can take a long time, and in the meantime your crops will be starved of those nutrients. Yield is minerals, sunshine and water, and when you limit minerals, you limit yields.
The Soil Health Mineral
In my opinion the final key to soil health is managing calcium because calcium is king. For soil health you need to maintain a certain sufficiency level of calcium in the soil, but it’s also important to add smaller amounts of a soluble calcium source that fits your soil and crops and provides minerals above and beyond what the soil can dish out. Calcium is the soil health mineral — it builds good soil structure, is a key nutrient for earthworms and interacts with soil aggregates to provide homes for other forms of soil life.
All of these management practices may sound difficult and complex, but at the end of the day achieving soil health on your farm is really simple. For healthy, high-yielding soils you need to deal with the physical (soil structure and tillage), chemical (nutrients) and biological (plant diversity and soil life) soil properties.
It’s a system. When you balance all of the components of the soil the system works and farming is a joy.
Gary Zimmer and Leilani Zimmer Durand are the authors of Advancing Biological Farming, a sequel to Gary’s earlier book, The Biological Farmer, both published by Acres U.S.A. Gary is also an organic dairy farmer, an accomplished speaker, a sought-after farm consultant and president of Midwestern BioAg, a biological farming products and services company. Leilani has written extensively about biological farming and runs training courses for farmers and farming consultants on the principles of biological farming at Midwestern BioAg where she serves as vice president of education initiatives.