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News Release

Cover Crops for the Intermountain West

Derek Tilley, PMC Manager
(208) 397-4133, ext. 104

Image of Cover Crops in the Intermountain West Technical NoteA cover crop is a crop that is generally not mechanically harvested but is grown to benefit the soil and or other crops in numerous ways. Cover crops can play an important role in increasing soil health, improving soil structure and reducing the need for costly inputs such as fertilizer and mechanical tillage. Cover crops can decrease erosion and increase water infiltration and retention. They also reduce nitrogen leaching and compaction and suppress weed growth. Adding cover crops to the rotation when technically feasible increases the presence of active living roots. Active roots produce more amino polysaccharides and glomalin because mycorrhizal fungus populations increase due to a stable food supply. Polysaccharides from plants and glomalin from fungi weakly hold the microaggregates together but are consumed by bacteria, so they need to be continually reproduced in the soil to improve soil structure.

Biodiversity (growing more plants in rotation) increases the success of most agricultural systems. Diversity above ground improves biological diversity below ground. The successful use of cover crops requires proper selection of species, correct timing of seeding and proper management practices. Best results are achieved when using a variety of cover crops to increase plant species diversity (which affects the below-ground fauna). Cover crop species can be divided into five categories: cool season grasses, cool season broadleaf species, legumes, warm season broadleaf species, and warm season grasses. Selecting a suite of species, some from each of these categories, fills the above and below ground niches and provides a diverse root system where soil microbes and other organisms thrive.

Using cover crops and increasing crop rotation diversity helps restore soil health, protects against erosion and groundwater leaching, and can provide feed and cover for livestock and wildlife. One rational for the increased use of cover crops is to provide a living, growing plant in our annual cropping system at times of the year when we typically have nothing growing. We can extend our growing season with cover crops.

This Technical Note provides descriptions and planting recommendations for several known cover crop species that may have applicability in Idaho. The species are divided into five functional groups: cool season grasses, cool season broadleaves, legumes, warm season broadleaves and warm season grasses.