Five Principles of Soil Health
Keep the soil covered
Minimize soil disturbance
Increase crop diversity
Keep living roots in the soil
If what I have been saying in the last several posts is true, tillage is a problem. And related to that, we have in agriculture a very long tradition of using annual plants-which must be planted each year-almost exclusively since the very beginnings of agriculture thousands of years ago. Until the late twentieth century annual crops meant tillage. In the middle of the twentieth century crop chemicals became available and there is now a group of farmers that are practicing annual plant production exclusively with use of crop chemicals for weed control in generally just two crops, corn and soybeans. Now, though, an individual who suffers from cancer has received a land mark settlement against Monsanto, makers of Roundup herbicide, which he claims caused his cancer. Other cases pend, and evidence mounts that all is not well. I fully expect to hear that all our foodstuffs are contaminated with one or another of the crop chemicals and that all our body tissues carry these chemicals, all with bad or unknown consequences. The future for heavy and regular, or even any, use of crop chemicals is not good.
On the other side of it are a group of organic farmers still depending very much on tillage for control of weeds. I am one of those. There is a tendency toward self righteousness in it. We sometimes fail to remember that tillage of annual plants is what destroyed the fertile lands of the Middle East centuries ago and also what reduced the organic matter levels in our Midwestern soils so drastically and so fast, all of this well before the advent of crop chemicals.
There are several approaches to reduce tillage in organic cropping systems. None of them are perfect. We can study carefully the impact of crop rotation on the control of weeds in the cash crops. It really does matter what is planted after what and we need to know more about both the crop plants and the weeds. We need to use cover crops, which are planted not necessarily for harvest, but to keep the soil covered and filled with living roots for as many months as possible. Cover crops can do double duty, for good planning can result in better control of weeds by use of covers and we already know that cover crops that are planted before, after, or interseeded with the crop plants do a huge service in building carbon-organic matter-into the soils.
We can also do whatever we can to embed our annual plant production into a system of perennials and perennial production. This is our practice. Our cropping acres spend just three years in annual crop production, which then alternates with three years of perennial hay for the cattle to winter on. This in addition to our permanent pastures means that at any given time two thirds of our acres are in perennials. Many of the smaller vegetable producers, such as community supported agriculture farms, are doing this very well.
And we can applaud the development of perennial wheat-Kernza-by the Land Institute in Kansas and do whatever we can to encourage this kind of research, both in and outside of the University system. This is a critical event in agriculture, as it moves us toward perennials.
Planned grazing systems are the gold standard for soil health. Cover crops and crop rotation with perennials can help us duplicate that effect on the cropping acres. There is much to learn.