When it comes to planting cover crops, having good seed to soil contact and maintaining proper planting depth is as important as when planting a cash crop. The 2014 cover crop trials were initiated in the mid to latter part of the optimal planting window for cover crops.
Aerial broadcast seeding works well for a variety of seed sizes, mixtures, and rates when the seed is broadcast directly onto freshly disturbed soil and either very lightly covered with soil or not covered at all. In no-till situations where cover crop seeds are flown into standing soybeans immediately prior to harvest germination, the establishment of the cover crop is generally poor. Similarly, instances where soil is allowed to crust over after tillage, but prior to aerial seeding, generally result in a poor cover crop stand if the seed is left uncovered.
In field studies, cover crop seed was broadcasted on freshly disturbed soil, and then the seed was covered in some fields and left on the soil surface in other fields. Field work in furrow irrigated fields consisted of a light pass with a hipper roller to cover the seed and prepare a good seed bed for spring planting. Under this situation, it is evident that much of the seed was knocked off the top of the bed and into the furrow, resulting in a sparse stand on top of the bed and a dense stand in the furrow. On flat-planted fields a harrow was used to cover the seed. Overall, on late-planted cover crop fields, no seed coverage scenario resulted in faster germination and better stand growth than in situations where the seed was covered.
Planting with an air-seeder or drill is a preferred planting method in the absence of freshly disturbed soils. Most cover crop mixes (including small seeds) flow very well through the large seed box on most drills. The small seed box works well for lower planting rates of species such as clover, but use caution when using a larger seed such as Tillage Radish at a low seeding rate as metering gears may crush the seed.
Cover Crop Planting Window
Disclaimer: Through the 2014 Cover Crop Trials we were able to observe the planting and growth of numerous cover crop species across more than 5,000 acres in the Mississippi Delta. The information provided here intends to summarize our experiences and lessons learned.