Energy balance and partitioning over a rotating rapeseed crop

Abstract

The quality of long-term eddy covariance data was evaluated by calculating the energy balance closure. The study was conducted in a single plot over four different years and crop types (rapeseed, wheat, peas, and rye) included in a rotation scheme governed by rapeseed. Calculations were made separately for a global dataset covering the whole four year/crop period and for each individual dataset belonging to each year/crop. The analysis was also carried out for the crop growing season (hereafter referred to as the maximum interest period—MIP). An imbalance of 14% was found when using the global dataset. A similar value of 13% was also obtained when the study period was limited to the MIP. A marked improvement was found in the energy balance closurewhensoil heat flux,GP , was corrected for soil energy storage. With this correction, a 92% and 93% closure emerged when the global dataset and MIP were studied, respectively. In addition, the energy partitioning in the various processes evidenced different results depending on the selected study period. When the global dataset was considered, sensible heat, H, usually played the main role in the energy partitioning. However, if only the MIP was selected, latent heat, LE, became the main driver dissipating energy while the crop reached full development for this period. The highest LE contributions to the energy balance were found for rapeseed and rye.