A fall cover crop established at the right time can do far more than improve weed control next season, the Weed Science Society of America (WSSA) says: it can reduce herbicide and nitrogen costs, cut soil erosion and ease the management of multiple herbicide-resistant weeds such as Palmer amaranth, waterhemp and horseweed.

"If farmers achieve their weed suppression goals, they will almost certainly realize other benefits along the way, such as improvements in soil health," said Michael Flessner, extension weed science specialist at Virginia Tech and chair of the WSSA Weed Loss Committee. Legume cover crops, he said, may allow farmers to reduce nitrogen fertiliser.

Timing is critical. Plant too late and the cover crop may not establish, especially less winter-hardy species. For weed suppression or lower fertiliser use, a high-biomass cover crop is needed in spring — "That biomass starts in the fall," Flessner said. He added that cover crops demand more management than winter fallow and pay off only when farmers have the will and the knowledge.

Rodrigo Werle, a cropping-systems weed scientist at the University of Wisconsin-Madison, said northern regions can benefit as much as southern ones if cover crops go in during September or October, or if spring termination is delayed. In the Midwest's corn-soybean rotations, the period just after harvest is the key window, and winter-hardy cereal rye is especially valuable because it overwinters and keeps growing in spring. "Simply having a cover crop is not enough: biomass matters when weed suppression is the goal," he said.

In a nationwide survey of nearly 800 farmers who use cover crops, 70.3% said they helped when transitioning to no-till.

Photo: USDA / Wikimedia Commons (Public domain)

Source: AGDAILY