Spatial and temporal variations of soil heat flux in a corn field

Soil heat flux is a critical component of the energy balance of agricultural crops. Observations have been made of the fraction of the net radiation that is comprised of soil heat flux, however, these fractions vary depending upon the crop and time of year. We designed a study to evaluate the spatial and temporal variation of soil heat flux under a corn cropping system in central Iowa. An array of 19 soil heat flux plates were placed 10 cm below the surface in a pattern across and down rows of corn. Plant height, LAI, and net radiation were also collected. Data were collected from planting through early grain fill. Results show complexities in the spatial distribution of soil heat flux as a function of row orientation and LAI with magnitudes in the ratio of G to Rn progressively decreasing with increasing LAI. Implications of these results will be discussed.