Planned Crop Rotation

Essentially a tool for annual cropping systems, crop rotation refers to the sequence of crops and cover crops grown on a specific field. Particular sequences confer particular benefits to long and short-term soil fertility, and to pest management.

Agronomic operations are especially dependent on crop rotations that include forage legumes. These provide the vast majority of the nitrogen required by subsequent crops like corn, which is a heavy consumer of that nutrient. Even when livestock are present to generate manure, the animals are largely recycling the nitrogen originally fixed by legumes in the system. An example of a basic agronomic rotation, typical of that found on midwestern organic farms, is shown in Figure 2.

Figure 2. Organic Field Crop Rotation

Corn Belt Model

Figure 2. Organic Field Crop Rotation

Organic Field Crop Rotation

The basic Midwestern rotation demonstrates the elegant way in which a whole farm system can function:

  • Legumes fix nitrogen in the soil, providing for subsequent non-legumes in the rotation.
  • Several insect pest cycles are interrupted, especially those of the northern and western rootworm species that can be devastating to corn.
  • Several plant diseases are suppressed, in cluding soybean cyst nematode.
  • Weed control is enhanced as perennial weeds are destroyed through cultivation of annual grains; most annual weeds are smothered or eliminated by mowing when alfalfa is in production.
  • Livestock manures (if available) are applied just in advance of corn, a heavy nitrogen consumer.
  • All crops can be marketed either as is or fed to livestock to be converted into value-added milk, meat or other livestock products.

Ralph and Rita Engelken, widely respected organic pioneers in the 1970s and 1980s, used a similar rotation that suited their hilly northeast Iowa farm and supported their main livestock enterprise, backgrounding beef cattle. (Backgrounding is confined or semi-confined feeding of young range stock to increase their size before final finishing in a feedlot.) The feed ration the Engelkens relied on consisted mostly of haylage, corn silage, and ground ear corn. The 6-year rotation/crop mix that allowed them to produce virtually all their own feed on 410 acres was

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