Soil Management for Vegetable Crops
Vegetable Crop Rotations
Growing the same crop season after season, necessitates the repeated use of similar cultural practices, including tillage, cultivation, fertilizer proportions, and timing within the season. Rotating with a diversity of root structures, from taproots to fibrous-rooted crops from a variety of vegetable families, will improve the soil’s physical, chemical, and biological health. Vegetables with tap roots are able to penetrate deep into the soil, making channels to help with air and water movement. Vegetables with fine and fibrous roots are able to get in between tightly packed soil particles, helping break them apart or, conversely, holding loosely packed soil particles together. Follow a legume crop, such as fava beans or soybeans, with a high nitrogen-demanding crop, such as sweet corn, to take advantage of the nitrogen supply. Rotating crops also makes better use of soil nutrients.
Rotating Vegetables by Family
In a rotation, vegetables are often arranged according to families so that individual vegetables from the same family do not follow each other in the rotation. Vegetables belonging to the same family can be considered as a rotational group because they are susceptible to many of the same diseases and insect pests, share similar nutrient requirements, and are treated with similar pesticides. For example, do not follow melons with cucumbers or squash, and do not plant peppers, eggplant, or potatoes where tomatoes grew the year before.
Vegetable Crop Compatibility
It is important to consider crop compatibility when planning a rotation. Some crops may have beneficial interactions and enhance yield, while others may have detrimental effects to subsequent crops. For example, many crops following the cabbage family may have lower yields. Sweet corn is a good selection to follow the cabbage family because it shows no yield decline. Potatoes are a good crop to follow sweet corn because research has shown sweet corn to be one of the preceding crops that most benefit the yield of potatoes.
Crop Rotations on Organic Farms
The National Organic Program rules specify that crop rotations are implemented to improve soil organic matter, manage deficient or excess plant nutrients, break pathogen and pest life cycles and provide erosion control. There is no specific number of years required for a crop rotation, but most organic growers have three- to eight-year rotations. Organic farmers usually grow a high diversity of crops to obtain the benefits of a diverse crop rotation. However, because of the large variation in acreage among crops and frequent changes in the crop mix due to weather and shifting market demands, planning crop rotations can be difficult.
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