They produce well on either light or heavy soils, and in matted rows or in hill culture. Plants are available in season at nurseries. ARS scientists conducted a two-year field study with the legumes. Maine potato farmers, who typically don't use cover crops, must apply 120 to 200 pounds of nitrogen fertilizer per acre, depending on the potato variety. But the researchers showed that planting one of the legumes allows reducing the rate without sacrificing yield.
Legumes take nitrogen from the air and store it in nodules on their roots.
After the legumes die and their roots decay, the next potato crop can use this nitrogen for growth. The study also revealed that growing a legume disrupted the life cycle in the soil of a Rhizoctonia fungus, the culprit behind yield-damaging lesions on potato plant stems. When one potato crop followed another, nearly 60 percent of the plant stems had lesions. Rotating potato with alfalfa cut this to 12 percent. Sugarbeet breeders can now get two new ARS-developed sugarbeet lines that combine resistance to the three diseases that cause nearly all disease damage to beets worldwide.