Determining water use of sorghum from two-source energy balance and radiometric temperatures
- 1Applied Physics Department, School of Industrial Engineering, University of Castilla-La Mancha, Av. España, s/n 02071 Albacete, Spain
- 2Instituto Técnico Agronómico Provincial de Albacete and FUNDESCAM, Av. Gregorio Arcos, s/n 02006 Albacete, Spain
- 3Earth Physics and Thermodynamics Department, Faculty of Physics, University of Valencia, C/Dr. Moliner, no. 50, 46100 Burjassot, Spain
Abstract. Estimates of surface actual evapotranspiration (ET) can assist in predicting crop water requirements. An alternative to the traditional crop-coefficient methods are the energy balance models. The objective of this research was to show how surface temperature observations can be used, together with a two-source energy balance model, to determine crop water use throughout the different phenological stages of a crop grown. Radiometric temperatures were collected in a sorghum (Sorghum bicolor) field as part of an experimental campaign carried out in Barrax, Spain, during the 2010 summer growing season. Performance of the Simplified Two-Source Energy Balance (STSEB) model was evaluated by comparison of estimated ET with values measured on a weighing lysimeter. Errors of ±0.14 mm h−1 and ±1.0 mm d−1 were obtained at hourly and daily scales, respectively. Total accumulated crop water use during the campaign was underestimated by 5%. It is then shown that thermal radiometry can provide precise crop water necessities and is a promising tool for irrigation management.