CHESTERTOWN — The next time you drive along a county road and see a small plane swooping low over the fields, don’t automatically assume it’s a “crop duster,” applying insecticide to the crops. Nowadays, it’s a fair bet that they’re doing aerial seeding — planting cover crops to prevent nutrient loss over the winter.
Cover crops — typically rye, barley and other small grains — are a big deal for farmers raising corn and soybeans, the most common cash crops on the Eastern Shore. Not only do they hold nutrients in the field during the seasons with the most rainfall, they make the farmers who grow them eligible for significant supplementary payments from the Maryland Department of Agriculture.
Aerial seeding allows the cover crop to be planted while the cash crop is still in the field, Paul Spies, conservation planner for the Chester River Association, said. That means the cover crop can be picking up nutrients just as the cash crop has reduced its nutrient intake, as both corn and soybeans do toward the end of their growing seasons. Having the cover crop started before the autumn rains begin is also important. If the nutrients remain in the soil, they can run off into the watershed.
Spies said microbes in the soil are active in turning nitrogen compounds in fertilizer into nitrates, well after the main crop stops taking up nutrients from fertilizer. That makes the nitrates vulnerable to being washed away with fall rain storms. The cover crops, by taking up the nutrients, prevent the nitrates from entering the watershed. They also reduce the amount of sediment washing into the streams and rivers.
Kent, Queen Anne’s and Talbot counties lead the state in the percentage of farmers planting cover crops, Spies said. Partly, that’s because the predominant crops are corn and soybeans, the ones most likely to benefit from the practice.
The majority of the cover crops are not harvested in their own right. The state sets dates by which the farmer is expected to plant the cover crops and by which they must be plowed under to make way for a new cash crop. If the farmer raises a herd of animals, he is allowed to use the crop to feed them. However, he is not allowed to sell the crop.
A less important category of cover crops can be harvested and sold, but the state does not support the farmer to the same extent as for those that are to be plowed under.
Most of the pilots who do crop dusting are also set up to do aerial seeding, Spies said. The only time there’s a problem getting them to do the work is when there’s some more lucrative assignment elsewhere in the state, for example spraying for gypsy moths in western Maryland. But the windows, set by the state, during which seeding is allowed, are “pretty flexible,” Spies said. “They can do a lot in a short time.”
Most corn growers in Kent and Queen Anne’s counties are now planting cover crops, Spies said. Soybeans remain “a challenge,” partly because if the cover crop grows too rapidly, it can complicate harvest. But there are ways to deal with that problem, mainly by adjusting the height at which the crops are cut.