Researchers at North Carolina State University have developed a model to determine optimal conditions for planting cover crops, which are grown between cash-crop seasons. This model aims to assist farmers in making informed decisions about their land management by considering factors such as current cash crop and fertilizer prices, as well as soil health.
The study analyzed 35 years of data from an experimental cotton farm in west Tennessee. It suggests that planting cover crops is generally beneficial on fields with healthy soil and no prior tilling. The cost of maintaining these crops may reduce the need for fertilizers, making them more appealing when fertilizer costs are high.
Cover crops are known to improve soil conditions by controlling water and fixing nitrogen. However, only about 4% of farmers nationwide use them due to perceived short-term costs. Rod Rejesus, professor at NC State and co-author of the study, said: “There is a lot of academic literature looking at short-term effects of cover crops, but our contribution here is in thinking about cover crops as a long-term investment.”
Zachary Brown, another co-author from NC State, explained that poor soil quality and low nitrogen fertilizer prices make adopting cover crops less advantageous. He stated: “If you’re starting from a place where the soil is degraded, it takes so long to build up better soil conditions that, from an economic perspective, it’s not worth it to plant cover crops.”
The research highlights that over time, certain cover crops like crimson clover and hairy vetch can replace nitrogen fertilizers. Brown noted: “The more you use cover crops, the fewer fertilizer inputs are needed.”
Published in the European Review of Agricultural Economics on May 31, 2025, the paper’s corresponding author is Le Chen from the University of Tennessee-Knoxville. Co-authors include Christopher N. Boyer and James A. Larson from the same institution.
Funding was provided by NASA and various grants from the U.S. Department of Agriculture.
