Termination timing is something all producers deal with each spring. All production decisions impact the profitability of farming operations, so sound decision making is key to a profitable cash crop and a beneficial cover crop.
There is a strategic balance between cover crop management and benefits. The balance will be different for every producer. The longer producers can wait to terminate the cover crop, the more residue they will have available for the cash crop in the field.
One of the most important aspects related to cover crop benefits is maximizing biomass for the following crop. Soil fertility and pH, seed quality and stand establishment are some of the major considerations that affect biomass production. Underground root biomass is beneficial, but the surface layer provides many direct benefits. This layer can help cushion rainfall impact to prevent soil crusting and minimize runoff, keep the soil surface cooler by shielding the soil from the sun and suppressing early season weed growth.
It is better to determine the optimum termination time using the growth stage and not the calendar date, but this is a constant balancing act for growers each season, particularly dryland growers. There will be some variability among cover crops, but generally, biomass is maximized by full bloom. Terminating the cover crop too early will likely limit the benefits of the cover for the following cash crop, but usually allows plenty of time for soil moisture to recharge through rainfall. However, letting the cover grow longer may significantly improve biomass and associated benefits but the risk for limited soil moisture at planting is greater.
For more information on cover crop termination and contributing factors, download a PDF.