Crop Rotation and Diversification

Image scanned from 1938 USDA Yearbook of Agriculture “Soils and Men” – Article: “Crop Rotation” by Clyde Leighty

The concept of crop rotation is not a new idea. It is an idea as old as agriculture. Crop rotation, simply put, is growing a variety of plants in a planned manner to ensure that one species is not grown in the same field for multiple years in a row. It requires a certain amount of diversification, and on the larger industrial scale it can present problems in the need for many different equipment schemes for planting and harvesting. Modern agriculture ‘solves’ this dilemma by ‘scientifically’ replacing, in the form of fertilizer, what it considers to be all of the nutrients that the crop has removed from the soil in the previous year, and replanting that same crop. There are many problems with this plan that are not in the scope of this article to address.

Many modern farmers will at least take one step towards a crop rotation by alternating corn with soybeans. This is definitely a vast improvement from the continuous corn monocrop in terms of soil nutrient conservation, and on the large industrial scale, this is about the best crop rotation we can ever hope that they will adopt. The soybeans recharge the soil with nitrogen and they, being a different species, do help to break up pest and disease cycles which are unique to corn. The problem of fertilizer, pesticide, and herbicide usage in this scheme is, again, not in the scope of this article.

The more species you introduce to a rotation, the more beneficial that rotation becomes. Each year added between Crop A and again growing Crop A in the same field is one more year that Crop A’s specific pests and diseases are not building up in the soil. It is one more year that the specific micronutrients that Crop A needs for optimum health are not being depleted. It is one more year that the soil profile is changed by different root structures which are not similar to Crop A’s root structure, thereby benefitting Crop A when it is replanted by having a more open and enriched topsoil, and possibly a more open and enriched subsoil if deep-rooted plants have been used in the rotation.

A perfectly attainable cattle farm rotation could be Corn, Soybeans, Corn, Hay, Hay. This rotation would show great returns for the farmer in increased yields of corn and soybeans. The hay crop would ideally be a mix of grasses and legumes, for example Timothy and Alfalfa, or Fescue and Clover, or compound mixtures of multiple grasses and legumes. Committing multiple years to the hay crop would allow those plants’ roots to reach deep into the subsoil and improve the soil structure during each rotation, encouraging better rain absorption and nutrient release for the corn and soybean crops.

My own rotation is and always will be a work in progress. I grow too many species. This is something I can admit to myself and I am always trying to work on whittling it down to our most important crops for simplicity. We currently do not keep livestock, so we are focused on human foods that are easily processed and digested, meaning corn and soybeans don’t come into the picture for us. I couldn’t really give an accurate example of my rotation because it is changing so constantly, and my rotations often involve 2 crops per year per field – a summer-ripening grain followed by a fall root or legume crop. Here is an example of what my rotation might look like on a given field:

Winter Rye, Fall Radishes, Winter Wheat, Fall Peas, Butternut Squash, Winter Peas, Spring Barley, Fall Turnips, Spring Oats, Fall Beans, Melons, Winter Peas, Clover, Clover, Spring Wheat – Winter Rye.

That is around a 9 year rotation, and even that doesn’t cover nearly everything that I grow, hence why I say it can’t really be an accurate example, but at least it’s an attempt at an example. One important concept in my rotation is to never let the field be empty for an entire season. Maybe I won’t harvest all the fall radishes that first year, even so I will still plant them. I will see an increased yield in the next crop that I will be thankful for.

With hard work and faith, crop rotation can not only conserve soil nutrients, it can increase nutrient availability as long as you are following a regular regimen of composting all available materials for addition to the fields at regular intervals.