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Management Considerations

Timing


Medic and clover mix. Photo by Chuck Ingels.
Medic and clover mix. Photo by Chuck Ingels.
The timing of establishment, termination and incorporation of a cover crop can affect the potential benefits provided by the cover crop and the performance of the cash crop. In regions such as northern California, where winter temperatures significantly slow the growth of winter cover crops, early fall planting is important to obtain a good stand establishment in the 1-2 months when temperatures are still relatively warm, for maximum biomass production and, in the case of legumes, nitrogen fixation. For summer cover crops, temperature but also availability of irrigation water may affect choice of planting date, with earlier spring dates likely allowing for better establishment with residual soil moisture if capacity to irrigate is limited. The best time for cover crop termination will vary depending on the cover crop species or mixture used, the weather, and the target cash crop.  Generally, winter cover crops decrease flexibility in planting dates, which could impact the production and profitability of spring crops.4 This impact could be positive or negative, as cool season cover crops could delay spring planting, or, conversely, they can improve early access to the fields in the spring by managing soil moisture. 

Additional Operations


In conventional systems, starter fertilizer applications may be used for cover crop establishment, with herbicides applications used for cover crop termination. In organic systems, cover crops may be terminated by rolling with a roller-crimper or mowing with a flail-mower.20 In both conventional and organic systems, cover crops are often flail-mowed to aid in incorporation.  The NRCS publishes cover crop termination guidelines for non-irrigated cropland (including fallow periods) with lots of useful information. Check the USDA Risk Management Agency website for the current Cover Crop Termination Guidelines.

Cost


Cover crop seed, planting, and land preparation costs vary widely. Refer to survey results from the SARE National Cover Crop Survey for recent cover crop economic trends. Based primarily on data gathered through five years of national cover crop surveys, Cover Crop Economics: Opportunities to Improve Your Bottom Line in Row Crops is a resource that explores the economics of cover crops in corn and soybean rotations. A cost study, Estimated Costs for a Winter Cover Crops in an Annual Crop Rotation, examines the costs and potential benefits of a cover crop in the lower Sacramento Valley in California. For some systems, the costs can be minor compared to costs associated with conventional management of winter fallows. 21, 30