Comparing the soil nitrogen losses for fall applied manure and inorganic fertilizer in the northern great plains

Abstract. Nitrogen (N) is one of the major nutrients needed by all plants for their growth and reproduction. However, manure or inorganic applied N of different forms can leave the soil volume by various paths such as ammonia volatilization (NH₃), aerial nitrous oxide (N₂O) loss, leaching (NO₃), and runoff and/or erosion. The losses of N from the soil not only decrease soil fertility and plant yield, but can also impair water quality as well as air quality. The objectives of the research were to measure the nitrogen losses (NH₃, N₂O, and leachate NO₃) from the soil for fall applied N and corn production, then compare the impact of applied nitrogen form (Manure with bedding (MB), Manure only (MO) and Urea only (UO)), in Brookings County, SD. The methods for collecting samples for soil N losses were semi-static open chambers for ammonia flux, static chambers for nitrous oxide flux, and suction lysimeters for soil water. The first-year of corn production results showed NH₃ flux, N₂O flux, and NO₃-N leaching for MB were 1.4 to 10.4 g-ha^-1 h^-1, 7.1 to 45.7 µg-m^-2 h^-1, and 3 to 14 mg-L^-1, respectively. Similarly, for MO the NH₃ flux, N₂O flux, and NO₃-N leaching were 1.3 to 1.8 g-ha^-1 h^-1, 2.0 to 14.7 µg-m^-2 h^-1, and 13 to 21 mg-L^-1, respectively. In contrast, NH₃ flux, N₂O flux, and leachate NO₃-N for UO in soil varied from 1.3 to 2.1 g-ha^-1 h^-1, 10.6 to 28.3 µg-m^-2 h^-1 and 7–19 mg-L^-1, respectively. Understanding soil N loss paths and related factors will help to identify appropriate management practices and nutrient management plans to mitigate excessive N losses to the environment.