University of New Hampshire scientists have found that forage radish is at the top of the list of beneficial cover crops farmers can use to suppress weeds and increase production values, according to new research from the New Hampshire Agricultural Experiment Station.
Cover crops, grown before or after cash crops are planted and harvested, protect soil from erosion, improve soil fertility, suppress weeds, and/or provide additional habitat for pollinators and other beneficial organisms. Because they minimise erosion and can help to keep nitrogen and other nutrients from leaching to ground waters or being lost via other pathways, they can be important tools for reducing pollution and other negative environmental impacts associated with agricultural activities.
The research was aimed at determining which cover crop species might be most useful for farmers in the New England region, said Richard Smith, assistant professor of agroecology.
It is presented in the article “In-Season and Carry-Over Effects of Cover Crops on Productivity and Weed Suppression” in Agronomy Journal.
The researchers examined the performance of eight different cover crops intended to fill the late summer and fall fallow period that occurs between crop harvest in the summer and the following springtime planting of a subsequent cash crop. This fallow period would typically follow the harvest of vegetable crops such as snap beans, broccoli, sweet corn, and spinach, or corn silage.
Cover crops were planted at the experiment station’s Woodman Horticultural Research Farm either as monocultures (one cover crop) or bi-cultures (mixture of two cover crops).
Crops planted include annual ryegrass, winter rye, alfalfa, crimson clover, white clover, hairy vetch, soybean, and forage radish. The researchers also included a control in which no cover crop was grown.
Some of these species, such as winter rye and hairy vetch, are quite common in the region where the work was undertaken. The rest are less commonly used as cover crops.
The two-year study allowed scientists to determine not just the average values for each cover crop but also the consistency of each cover crop’s performance.
“Based on our research, we found that forage radish was consistently among the highest biomass-producing treatments in the fall, provided excellent fall weed suppression, and resulted in some of the highest production values in the test-crop,” Smith said.
“We were particularly surprised with how well the forage radish performed, both in terms of fall growth and fall weed suppression, and how much of an impact it had on the subsequent test-crop despite the fact that it died in the winter,” Smith said.
There is growing interest in using cover crops to improve soil health and sequester carbon in the soil. Many New England farmers are already using some of these cover crops.
Smith said it was not uncommon for as much as 50 per cent of a farm to be in cover crops during the growing season.
But there is a relative lack of information about how well different cover crops perform in the region, particularly in regard to weed suppression, given the short growing season and relatively intense winters.
The study is part of a larger research effort that aims to provide New England’s farmers with science-based information about agricultural practices that reduce the need for economically and environmentally costly agrichemicals and other external inputs. The goal is to develop biologically based practices that are appropriate for their operations and that improve their bottom line.