Cover Crop Customers' Fields
Tillage radishes can be used after a traditional corn harvest but in drought situations, early crop removal lets you establish these cover crops that wouldn't have enough time after a normal corn harvest."
Duiker did emphasize the importance of considering herbicide carryover, especially following drought. "The chemicals may be in a fairly shallow soil layer," he said. "Crops like tillage radish and legumes can be damaged, though grass cover crops are less likely. Check rates and how sensitive your cover crop is."
Of course, the viability of cover crops assumes rain. Some cover crops, like annual ryegrass, only need a heavy dew to germinate, but without soil moisture will quickly die. Whether the cover crop is drilled into the soil or broadcast also makes a difference. Drilled seed has a much better chance of germination compared to spread or aerial applied seed. However, even non-germination in the fall doesn't signal a complete loss.
"In 2010 we didn't have nearly enough moisture to get the cover crops going, and several kinds of crops didn't come up until spring," noted Kok. "We still got some benefits with beautiful stands of cover crops before planting."
If rains do come this fall, cover crops will grow vigorously and create a good situation for planting, with the option of killing the cover crop first and planting or drilling into the cover crop and controlling it after. "Either way, the cover crop will pull excess moisture out, and the grower ends up with a better soil structure that can be driven on sooner than with no cover crop," explained Kok.
If the drought continues into 2013, cover crops can still be advantageous; however, they should be killed off early enough to not steal moisture from the next crop. Early control does sacrifice some biomass production and nitrogen fixation from legumes in a mix, noted Kok. Letting it grow opens up other opportunities for haying and grazing as noted by Duiker. Growers need to check with crop insurance agents to verify grazing or haying is allowed.
LEARNING CURVE FOR RETAILERS
Kok pointed to an inherent conflict some retailers see with cover crop promotion. "Some retailers see guys growing cover crops like clovers and other legumes as growing their own nitrogen; others see it as a great opportunity to sell cover crop seed and apply it," he said. "Some don't want to mess with the complexity of a new business and the knowledge needed."
Kok noted that some retailers are purchasing highboys and converting them to cover crop seeders. Others are taking on the role of aggregators, finding farmers who want cover crops applied and contracting for them with an aerial applicator, turning it into a turnkey operation. Making sure the seed is applied in a timely manner takes a lot of pressure off the farmer.