Soil Nitrate Leaching Impacted by Cover Crop Mixtures and Simulated Winter Warming.

This thesis observed the effects of simulated winter warming, and cover crops planted between growing seasons on agricultural nitrate (NO3-) leaching. In a field study, using monolithic soil column weighing lysimeters with lower boundary controls to directly measure drainage, two soils to broaden the scope of this research, and soil solution NO3- concentrations from below the root zone were used to determine NO3- leached during the study period. NO3- leaching was significantly reduced by planting cover crops after harvesting the main crop by 69-77% depending on soil-type. Heaters were used to simulate warmer winters, which increased drainage, and soil NO3- concentrations below the root zone; however, the increase in drainage, and the increase in soil NO3- concentrations was separated temporally and did not have a significant effect on NO3- leaching. Observed effects of cover crops and warming on drainage, NO3- concentrations, and NO3- leaching are reported based on seasonal climatic variations.