Evapotranspiration partitioning and crop coefficient of maize in dry semi-humid climate regime

• Published in: Agricultural water management Vol. 236; p. 106164
• Main Authors: Wang, Yunfei, Cai, Huanjie, Yu, Lianyu, Peng, Xiongbiao, Xu, Jiatun, Wang, Xiaowen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.06.2020
• Subjects: Crop coefficient; Eddy covariance; Energy fluxes; Evapotranspiration partitioning; Evapotranspiration partitioning; Eddy covariance; Crop coefficient; Energy fluxes
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/j.agwat.2020.106164

•The reliability of eddy covariance technique to measure the ET in summer maize cropland was evaluated.•The diurnal and seasonal variation of energy fluxes and seasonal variations of evapotranspiration partitioning in maize field were revealed.•This study provided the local Kccurve and revealed its controlling factors. Guanzhong Plain is one of the most critical maize production areas in Northwest China. It is essential to study the maize irrigation requirement and improve water use efficiency in this area. There is a lack of knowledge about the evaporation portioning and irrigation requirements of crops grown in this region. Based on evapotranspiration observed in a maize cropland using the eddy covariance (EC) technique during four growing seasons (2013, 2014, 2015, and 2017), the seasonal variation of evapotranspiration components and the crop coefficients (Kc) for summer maize in a dry semi-arid area were determined. Energy partitioning has an obvious seasonal variation during growing seasons. The pattern of evapotranspiration partitioning has a clear seasonal variation with the development of the canopy. The pattern of the ratio of transpiration (T) to evapotranspiration (ET) is consistent with the canopy development. For four growing seasons, on a seasonal basis, the ratios of T to ET and E to ET were comparable. In addition, the locally developed crop coefficients were 0.57, 1.01, and 0.50 for the initial, mid, and late stages, respectively. The single crop coefficient derived from local datasets can provide a good prediction of ET. The Kc values reported in this paper were consistent with previous studies conducted in other regions using EC systems but were generally lower than the Kc values derived from ET data measured by lysimeters, the Bowen Ratio Energy Balance system, and the soil water balance method. This indicates that the variability of the locally developed crop coefficient caused by measurement methods is higher than the variability caused by climate.