Crop Planning, Rotation and Yield

Why rotate crops

Growing the same crop on the same ground year after year lets its pests, diseases and weeds build up, and draws on the same nutrients from the same depth of soil. Rotation breaks that pattern. A field that grew corn last year grows soybean this year, and the corn rootworm that hatches in spring finds nothing to eat.

The main benefits come from a few mechanisms:

• Pest and disease cycles are broken, because many soil-borne problems only survive on one crop family.
• Legumes such as peas, beans, clover and alfalfa fix nitrogen from the air with the help of root bacteria, which reduces the fertilizer the next crop needs.
• Crops with different root depths use different layers of soil and leave different residues, which helps structure and organic matter.
• Weed control gets easier when planting dates and herbicide options change from year to year.

Our article on the purpose of crop rotation goes through each benefit with examples.

The four-field crop rotation

The best-known four crop rotation is the Norfolk four-course system that spread through English farming in the 18th century. Each field moved through wheat, then turnips, then barley undersown with clover, then clover grazed or cut for hay. The turnips and clover fed livestock over winter, the animals’ manure went back on the land, and the clover put nitrogen back into the soil. It replaced the older medieval three-field system, which left one field in three fallow each year.

The same idea still works on a modern 4 field crop rotation, with crops chosen for today’s markets. A vegetable grower might rotate four groups of beds:

Each group moves one place along every year, so no family returns to the same bed for four years.

What makes a good crop rotation

There’s no single best crop rotation; the right one depends on your climate, soil, markets and machinery. Arable farms in the US Corn Belt often run corn and soybean in alternate years. In Canada and southern Australia, cereals are commonly rotated with canola and pulses such as lentils or field peas. Whatever the crops, good rotations tend to share a few principles:

• Don’t follow a crop with another from the same family.
• Include a legume at least once in the cycle.
• Alternate deep-rooted and shallow-rooted crops.
• Use cover crops to keep the soil covered between cash crops.
• Leave longer gaps for crops with persistent soil diseases, such as clubroot in brassicas.

Rotation is often combined with intercropping, growing two crops together in the same field. Our guide to crop rotation and intercropping compares the two.

Building a crop rotation planner

A crop rotation planner doesn’t need special software. A spreadsheet with one row per field and one column per year does the job for most farms. The work is in the setup:

1. List every field or bed with its area and what grew there for the last three to five years.
2. Group your crops by family and decide on the rotation length.
3. Assign next season’s crops, checking each field against its history.
4. Note anything that breaks the plan, such as a disease outbreak or a field that flooded, so next year’s choices account for it.

Field history is the part most farms lack. Satellite records help fill it in: with Farmonaut satellite crop monitoring you can compare crop health on the same field across dates and seasons and see which zones underperformed, which is useful when deciding what goes where next year. Our article on crop planning and management covers the wider planning process.

Rotation and the farming cycle

The farming cycle runs from planning through soil preparation, planting, crop care and harvest to storage and sale, and then back to planning. Rotation decisions belong at the very start, because they shape seed orders, fertilizer budgets and field work for the whole season. Our guide to the five stages of farming follows a crop through each step.

The end of the cycle matters just as much. Harvest is when you learn which fields did well, so note yields, problems and anything unusual while it’s fresh. Those notes become the field history your next rotation plan is built on.