Cover Crops and Conservation Tillage
for Soil Erosion Control on Cropland
First-year Rotations
Crownvetch seedlings are sensitive to herbicides and crop competition for the first year after seeding. Also, you should avoid tillage during the first year after seeding; otherwise, your crownvetch and birdsfoot trefoil seeding will be lost. Only after crownvetch is well established can you chisel plow, heavy disk, or use other minimum-tillage tools without hurting the crownvetch stand to much. Tillage of any kind will reduce the birdsfoot trefoil stand since it can't recover from underground root stocks. Moldboard plowing can never be done without virtually wiping out both the birdsfoot trefoil and crownvetch.
No-till corn - First-year rotations
No-till corn is perhaps the best crop to plant the year following a birdsfoot trefoil/crownvetch seeding, since there are more herbicide choices for good weed control, and corn doesn't exert excessive competitive pressure on the cover crop. Don't use Roundup, Touchdown, 2,4-D, or simazine (Princep) on 1-year-old crownvetch. A mixture of Gramoxone Max (if it is needed for burndown) plus Lightning and Basis Gold; or Gromoxone Extra plus Basis and Bicep with either Lasso MT, Dual II, Harness, Topnotch, Frontier, or Prowl at one-half the labeled rate for your soil type may be used safely without severely injuring birdsfoot trefoil or crownvetch the first year after seeding. Choose one of the suggested herbicide programs in Table 4. If crownvetch should ever appear to be making too much growth (more than 6 inches of growth when corn has less than six leaves), suppress it with Banvel or Clarity mixed with Basis (Treatment 16, Table 4). For crownvetch/birdsfoot trefoil mixtures, substitute Basis Gold for Basis in the same treatment. The goal is to suppress the cover crop 95 to 98% for the first 4 to 6 weeks and then let the birdsfoot trefoil and/or crownvetch recover. If these cover crops are sufficiently suppressed, they will never bloom except around the edge of the field where they get more sunlight.
