According to the 2017 Census of Agriculture, cover crop acres in the U.S. increased to more than 15 million acres. Eight states, including Nebraska and Missouri, have doubled cover crop acres since 2012. Nebraska farmers reported 747,903 cover crop acres. Texas tops the list, followed by Iowa, Indiana, Missouri and Nebraska.
While farmers still have questions about how to best implement cover crops into their cropping systems, Nebraska On-Farm Research trials and observations by veteran cover crop farmers might give an indication about where to start. Here are a few practices to try out on your farm.
Diversify outside of a corn and soybean crop rotation. This practice may be the most difficult, but it could be the linchpin to success. For experienced cover croppers like Cedar County farmer Jeff Steffen, getting a cereal crop like oats into the corn and soybean rotation is the crucial component. For him, oats is a low-cost crop that can yield up to 120 bushels per acre or more, at a test weight of 38 pounds per bushel. Steffen harvests only the heads, leaving a tall stubble and spreading the straw on the field. With an earlier harvest time on the cereal grains, cover crops can be seeded earlier in the season, allowing more time to build biomass and provide more grazing than with just corn and soybeans. Steffen says that is why corn crops following oats get a strong yield boost the following year. “The problem with just corn and soybeans is that you can’t get enough carbon in the system to raise organic matter,” he says.
Try planting shorter-season corn or soybeans. Getting the timing of cover crop planting right is crucial. “There are several strategies producers are trying,” says Laura Thompson, Nebraska Extension educator and Nebraska On-Farm Research Network coordinator. “One of those is planting shorter-season corn and soybeans. In our on-farm research network, growers have been evaluating their yields when they plant a shorter-season hybrid or variety,” she says. “The goal is to determine if they can use a shorter-season variety without losing yield, to allow more time to establish cover crops in the fall.”
There is variation in the results because of genetics and growing conditions. “This is one option producers might want to evaluate in their own growing environment and with their preferred genetics,” Thompson says.
Graze with cattle. “Probably the most consistent way we have seen cover crops work well is in a more diversified system, where the cover crop or forage is able to be grazed,” Thompson says. “For some growers who have cattle, this is a very natural fit.” For those without cattle, it might be feasible to form partnerships with neighbors with cattle to better use cover crops and fit them into the system, she adds.
Test fields with rye cover crops and without. “Try with and without a rye cover crop, randomized and replicated several times in their field,” Thompson suggests. “We would encourage these growers to maintain the ‘with and without’ cover crop strips for several years in the same place to better document the long-term impacts.
“Producers should capture the yield data for the crop following the ‘with and without’ rye treatments,” she says. “They should also collect other information, like cover crop biomass and soil organic matter.” Researchers encourage farmers to take photos, and even obtain aerial imagery of the fields being studied, to help document cover crop establishment and the differences in cash crops following cover crops.
“By keeping the strips in place over a longer period, it helps us capture long-term differences, which is often difficult to do,” Thompson says. “This is a great starting point for those who are interested in learning more and evaluating cover crops on a smaller scale, before diving in with their whole operation.”
For those interested in setting up cover crop on-farm studies, contact your local Nebraska Extension educator, Thompson or Nebraska Extension educator Keith Glewen for more information. You can learn more online at UNL’s CropWatch On-Farm Research Network webpage.