Chapter 6

Cover Crops for Organic Farms

Cover Cropping Systems

Choosing a cover crop depends largely upon the objectives in the overall farm management plan. There are four main categories of cover cropping systems—monocultures, mixtures, insectary mixes, and resident vegetation.

Monocultures

Single species of cover crops are often planted if operational constraints limit selection to a single species or when the species has a history of proven performance. The use of a single species is common practice with species such as cereals, “Blando” brome, and bur medic.

Mixtures

Planting cover crop mixes, often referred to as cocktails, may be a viable means to increase the ecological stability and resilience (i.e., ability to recover from extreme stress or disturbance) of cover crop communities, contributing in turn to greater and more consistent productivity. For example, using drought-tolerant plants in a perennial mix builds in persistence for dry years. Adding grasses to a fall-seeded legume improves soil coverage over winter and increases the root mass to stabilize topsoil. A faster-growing cover crop serves as a nurse crop for a slow-growing cover crop while covering the ground quickly for erosion control. Mixing cultivars of a single species with varied maturity dates and growth habits maintains optimum benefits for a longer time. They are often more resilient, can provide a higher quality residue, and their carbon:nitrogen ratio can be targeted to satisfy cover cropping objectives.

Insectary Mixes

Insectary mixes includes broad-leaved, flowering plants that include both annual and perennial species, which are sown for the purpose of attracting beneficial insects. These mixes vary greatly among seed companies but usually contain a number of different wildflowers.

Resident Vegetation

Resident vegetation is naturally-occurring vegetation, or “weeds” that provides some of the benefits of sown cover crops, such as providing traction, improving soil tilth, and attracting some beneficial insects.

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