Soil and Fertility

Deep sandy to loamy soil with a pH of 6.5 to 7.5 is ideal for early legumes, and heavier soils, while more productive, should be used for main-season production. Most soils in Utah are suitable, provided they are well-drained, fertile, and do not have a salt buildup. A well-prepared seed bed encourages uniform planting conditions. Several weeks before planting, prepare the field. If the site has drainage issues, Legumes consider 6- to 8- inch raised beds as most legumes are prone to root rot diseases in wet, poorly drained soils.

The legume crops may be sensitive to residual herbicides from the previous crop, so pay attention to prior cropping patterns and use crop rotation when required. 

Before planting, have the soil tested to determine nutrient needs and deficiencies. Soil sampling approaches and interpretation of the tests are found on the Utah State University Analytical Laboratories website. Organic growers should incorporate composted organic matter before planting to improve soil fertility. If you regularly apply compost or manure, periodic soil testing is critical. Regularly adding organic fertilizers can result in the buildup of salts and excess levels of some nutrients.  Initially applying 5 tons per acre of high-quality compost of known nutrient analysis can provide all nutrient needs. Broadcast the compost over the whole field or band it on the planting row before incorporating it into the soil.

Generally, ¼ to ⅓ of the nitrogen and all the phosphorous and potassium is applied prior to planting (either broadcast or banded). In soils with high soil test P and K levels, broadcasting all of the fertilizer is acceptable. Banding is a good method to ensure the fertilizer is near the plant. Fertilizer bands should be 3 inches beside and 3 inches below the seed to minimize salt injury. 

Nitrogen (N) – Apply up to 20-30 pounds N/acre for peas and 30-50 pounds for beans prior to planting. Base legume N needs on prior cropping history, residual soil N levels, and prior additions of compost or manures. Be sure to inoculate legume seeds with the appropriate rhizobium for the crop. Inoculated legumes then produce their own nitrogen, so no sidedress N is required. Some legumes are prone to zinc, iron, or manganese deficiency, particularly if grown in soils with pH over 8.0. Use soil testing to identify if these trace minerals are required, and then add them to the broadcast or side-dressed fertilizer applications.