Cover crops are an investment much like any other input for agricultural operations. In order for producers to get the most out of their investment, cover crops should be managed to maximize benefits while minimizing costs. Many of the benefits associated with cover crops are enhanced by increasing cover crop biomass.
For example, greater amounts of residue on the soil surface following cover crop termination can help suppress weeds and improve soil moisture retention during the cash crop growing season.
When making management considerations for cover crop biomass production, there are few costs that producers can control. These tips can help producers reduce cost while maintaining biomass production:
Planting early is critical for producing high cover crop biomass, which can maximize season-long cover crop benefits for the cash crop that follows. Recent research in Alabama shows that a rye cover crop planted in mid-October with no N added produces the same amount of biomass as rye planted in early December with 90 lbs N applied (see graph below).
Optimize seeding rates
For producers drilling 90 pounds per acre or more of small grain (ex. Cereal rye, oat) as a cover crop, consider reducing seeding rates to approximately 40-60 pounds per acre. Research in Alabama has shown that increasing seeding rates above 40-60 pounds does not increase biomass of small grain cover crops like rye, oat, and triticale.
Supplemental N fertilizer may be required for producers unable to plant early to ensure they achieve adequate biomass levels, particularly for late-planted cover crops. It is important to consider weather conditions when determining when to apply N fertilizer. In years with heavy rainfall, applied N can be lost through leaching deeper into the soil profile.
To improve fertilizer use efficiency, it may be beneficial for producers to wait until spring to make N applications in years when heavy rainfall is expected throughout the fall and winter months (for example, in an El Niño year) or for late-planted cover crops.