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Research Shows Moisture Timing Key to Nitrogen-Fixing Cover Crop

University of Texas Rio Grande Valley graduate student Stephanie Kasper conducted research under a Southern Sustainable Agriculture Research & Education (SSARE) grant on how moisture and nutrient availability affect the ability of the cover crop Iron and Clay Cowpea to fix nitrogen. Although soil moisture and micronutrients have an impact on a plant’s ability to produce nodules, this research showed that timing of moisture has an even larger impact on nodulation. “During the course of the plant’s lifetime, it is most important that it has moisture during the beginning of the season, when it’s first starting to grow and it has the opportunity to form the relationship with the bacteria. If it is dry during the beginning of the season, and the relationship between the plant and bacteria doesn’t form because there isn’t enough moisture in the soil, then you probably won’t see nitrogen fixation even if you get water later,” explained Kasper.