Double crops protect soil against wind and water erosion. Root biomass from double crops enhances soil fertility by building organic matter. More corn stover could be removed because the soil is better protected, the MSU researchers reported in their study entitled “Biofuels Done Right: Land Efficient Animal Feeds Enable Large Environmental and Energy Benefits.”        

However, not all land is suitable for double cropping. Land with insufficient soil moisture would not support the subsequent row crop. Double cropping can also result in lower grain yield and more potential for pests.

For these reasons, the MSU researchers limited their analysis of double crops to one-third of current corn and soybean land used for feed, exports or ethanol (about 49 million acres). They also assumed the double crops would be produced using no-till.

Glen Murphy, territory agronomist for Monsanto’s DeKalb and Asgrow brands in southern Indiana, says that a corn-wheat-soybean rotation is common throughout Kentucky and southern Indiana. Growers have often planted winter wheat in highly erodible areas and when wheat prices are high. But, he adds, double cropping has decreased in the last few years because growers prefer getting the full yield potential of corn or soybeans.

Double cropping can help improve soil tilth over the long term, however, so it gradually leads to better emergence and better crops, Murphy says. Double cropping, generally done using conservation till, may not pay off for five to 10 years.

Double cropping also requires more advance planning, which includes selecting varieties or hybrids that will mature early enough to allow time for fall field operations and getting the winter crop established before harsh winter conditions begin.

Growers need to terminate the winter crop with a burndown herbicide, such as glyphosate, in the spring. If the wheat grows too tall, it can become more difficult to control, attract insects and, in some cases, tie up nutrients — all of which can reduce corn yields.