Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
Fall is a good time for vegetable growers to plan or revise rotations. The following are some general thoughts on rotations.
Three years is the minimum rotation for crops in the same family or with similar disease profiles. Five or more years is recommended for vine crops. Field crops such as corn, small grains, and sorghum are good rotational crops. Soybeans may be a good rotation for some crops but not for legumes such as lima beans or snap beans.
Problems often arise where growers increase vegetable acreage without adequate ground for rotation. Base your acreage decisions on available fields that fit rotational schemes.
Where vegetables are the main income for a farm, consider using soil improving crops (green manures, biofumgant crops, soil improving cover crops) in lieu of standard field crop rotations. While some income will be lost on field crop revenues, there will be long term gains with improved vegetable yields.
Where rotations are tight, it is critical to consider some disease reducing crops in the rotation (mustard family and sorghums for example). Try to build up organic matter in these fields as this generally improves overall soil health.
Rotate vegetable families where possible. Do not rotate within a family (such as the bean family, vine crop family, or tomato family). Sweet corn is an example of a good vegetable rotational crop to break up disease cycles on many farms.