Effect of Nitrogen Fertilization and Cover Crop Mixtures on Potato Tuber Yield, Nutrient Density, and Nitrate Leaching.

Excessive use of nitrogen fertilizer in potato fields has resulted in increased contamination of water resources and costs of production due to high mobility of nitrate in the soil. Using cover crop mixtures may provide nitrogen to the following potatoes; at the same time reduce nitrate leaching in the soil. Therefore, the efficiency of cover crop mixtures and nitrogen fertilizer rates was evaluated in a 2-yr field experiment at the research farm of University of Massachusetts, Amherst. Cover crop mixtures included: oat/forage radish, oat/peas, rye/forage radish, rye/peas, peas/forage radish along with no cover crop plots and four nitrogen fertilizer rates (0, 50, 100, 150 kg N ha^-1) supplied as urea. Measurements were made for nutrient density of tubers, tuber yield, and nitrate leaching below the cover crop root zone. Our results indicated that cover crop mixtures had the potential to provide nitrogen with the succeeding potatoes, resulting in less nitrogen application and higher tuber yield and nutrient density compared with no cover crop plots. Also, less nitrate was leached into the soil with the cover crop mixtures compared to fallow.