Impact of Change in Soil Thermal Gradient on the Fate of Soil Nitrogen

Warming climate trends will shift the soil thermal gradient and thus impact the soil-nutrient dynamics. This impact will be more pronounced in areas where air temperatures have been significantly less than those of the vadose zone. It has been observed that the soil nitrogen content in the form of nitrate and ammonium has increased in water bodies with an increase in temperature. This observation can be owed to the reason that the denitrification process is significantly affected by warm temperatures. Nitrogen content in the soil thus can be expected to change due to increasing temperatures. The present study attempts to find the effect of air temperature on soil root zone properties (viz. soil temperature and soil moisture content at different depths) consequently affecting soil-nutrient status. A support vector regression (SVR) model was trained to develop a regression between air temperature and soil nitrogen status at different soil moisture contents. The model was applied to simulate the future (i.e. years 2030 and 2050) soil nitrogen content at different depths for different soil temperatures and moisture contents. The effect of increasing temperature on the fate of soil nitrogen was predicted based on the optimal temperature range required for the chemical reactions. The model used the data from experimental watershed Bear Brook Watershed, Maine and soft data from the Global Land Data Assimilation System (GLDAS) for prediction and validation purposes.