Spatial Distribution of Soil Heat Flux and Growing Degree Days

Abstract

AbstractIn agricultural areas, groundwater pollution by NO2‐3 from excessive fertilizer, manure, and amendment applications is becoming a serious problem. To control such pollution, assessment of the potentially most critical recharge zones is needed. Spatial parameterization of soil heat flux can delineate areas of high C and N mineralization and help identify such zones. Soil heat‐flux distributions were estimated on a central Pennsylvania farm and surrounding watershed from changes in the optical‐rotation angle of a sucrose solution, water content, and bulk density. The change in rotation angle is a function of soil temperature and occurs during the chemical reaction when sucrose is converted to glucose and fructose. Volumetric soil water content and bulk density were used to compute soil heat capacity. Estimates of soil temperature and heat capacity were combined to produce estimates of soil heat flux and growing degree days at different scales. Their spatial distributions were computed using geostatistical techniques. Measured and derived properties were found to exhibit anisotropic spatial structure related to soil‐forming factors and scale. Land‐use management implications suggest that this method identifies warmer or colder zones as well as areas with high or low C and N mineralization potential on farm and watershed scales.