Cover crops are legumes, grasses or small grains that are established after a crop is harvested in the fall. Cover crops are planted to: 1) control erosion during periods of inadequate soil cover; 2) retain a portion of the nutrients remaining in the root zone and make them available for the next crop; and 3) improve infiltration and thereby reduce surface runoff to nearby streams.
Cover crops are one of the most cost-effective and environmentally sustainable ways to control soil erosion and reduce nutrient runoff into the Chesapeake Bay and its tributaries during the winter months. Yet, in order for cover crops to be effective in erosion control and nutrient uptake, they need to be planted at the proper time. Cover crops must achieve a certain amount of vegetative growth by mid-December in order to provide the maximum erosion control and nutrient uptake benefits. The combined canopy and surface cover must achieve at least 50 percent uniform ground cover going into the winter to provide adequate erosion control protection and at least 80 percent uniform ground cover is needed to achieve the maximum nutrient uptake benefits.
The latest cover crop research reveals that the early establishment of a fall-planted, small grain cover crop is critical in achieving the substantial uptake of excess soil nutrients and providing adequate erosion control in the fall. The research indicates that nutrient uptake and ground cover diminished rapidly when cover crops were planted beyond the optimal planting dates.
The new thinking is that for a small grain cover crop to provide the maximum benefits, they must be planted earlier than 14 days prior to the average date of the first killing frost (Level 1 - early). The second best scenario would be to plant the cover crop within 14 days of the average date of the first killing frost (Level 2 - standard). Finally, there are limited benefits to planting a cover crop later than the average date of the first killing frost. To capture this limited benefit, the cover crop must be planted between the average date of the first killing frost and up to three weeks after (Level 3 - late).
The average date of Fulton County's first killing frost date is October 10; therefore, early planting (Level 1) should occur up through September 25, standard planting (Level 2) should occur from September 26 through October 10 and the late planting (Level 3) should occur from October 11 through October 31.
The baseline efficiencies for erosion control and nutrient uptake for fall-planted cover crops are: Level 1 (early) is 70 percent, Level 2 (standard) is 65 percent and Level 3 (late) is 30 percent. There are no fall or winter benefits associated with cover crops that are planted too late. The only benefit of a late cover crop occurs in the spring during growth. Excess soil nutrients are reduced; however, there is not adequate erosion control protection and as a result, soil is lost.
This past fall, the Fulton County Conservation District's Cover Crop Incentive Program (CCIP) had established the following deadlines for planting cover crops: oats - September 10; barley - October 1; wheat - October 15 and rye - November 1. A total of 41 participants planted 301 fields for 1,891 acres of cover crops. Only four of these operators had all of their cover crops certified for payment because they had achieved the required amount of cover; another 13 had a portion of their acres certified. Twenty-four operators had no cover crops certified for payment, because they were not able to achieve the necessary 50 percent uniform ground cover by January 1, 2009. In all, only 641 acres had achieved 50 percent uniform ground cover, compared to 1,250 acres that did not.
Due to these results and the latest research, the district has decided to make some significant changes to the 2009/2010 Cover Crop Incentive Program. Sign-up will begin April 13, 2009. The incentive payment for cover crops planted by September 25 will be $50 per acre and for cover crops planted by October 10 will be $30 per acre. There will be no incentive payments offered for any cover crops planted after October 10. The cover crop may be established via no-till or reduced tillage (non-inversion tillage) and be following corn silage. The cover crop must still achieve 50 percent or greater uniform ground cover by January 1, 2010 in order to receive the incentive payment. In addition, the district plans to contract with several custom operators in the area to plant cover crops within 48 hours of being notified that the silage has been harvested. Our cost per acre to plant the cover crop would be subtracted from the $50 and $30 per acre incentive payments stated above. The program applicant will need to supply their own cover crop seed.
If you are interested in participating in the district's 2009/2010 Cover Crop Incentive Program, please contact ag specialist Doug Valentine, at 717-485- 3547, extension 117 for more details.