Comparison of actual evapotranspiration of irrigated maize in a sub-humid region using four different canopy resistance based approaches

The single layer Penman-Monteith (PM) method is widely used method for the estimation of crop evapotranspiration (ETc). The accuracy of ETc estimate relies upon the quality of input weather data and capacity to approach adequately canopy (r(c)()) and aerodynamic resistance (ra). In this study, the PM method was used to estimate daily crop evapotranspiration of irrigated maize for the years 2013 and 2014 in a sub-humid region. Four different approaches (Monteith, Kateiji-Perrier, Todorovic, and Jarvis) were used to estimate canopy resistance and, then after, crop evapotranspiration by PM equation were evaluated. The comparison was made to daily crop evapotranspiration obtained from the soil water balance (SWB) and soil water content variation measured by time domain reflectometry (TDR). The cumulative crop evapotranspiration of SWB, Monteith, Katerji-Perrier, Todorovic and Jarvis approach was respectively, 260.4, 266.8, 252.8, 263.4, 256 mm for the year 2013, and 250.5, 257.7, 240.6, 251.8, 247.6 mm for the year 2014. The comparison of results and the statistical analysis confirmed that Todorovic and Jarvis approach gave reliable values, while the Katerji-Perrier approach could be used as an alternative method.