Comparison of calculating methods of forage crop water requirements and correlation analysis in the grassland of Xilinguole

Crop water requirements are most part of water consumption in agricultural aspect. Currently, there are lots of methods of calculating crop water requirements. According to the observation data and weather data in typical grassland in Xilinguole of Inner Mongolia from 2004 to 2005, crop water requirements were calculated by water balance and evaporation pan method directly. Also, crop water requirements were calculated by crop coefficient K, and Penman-Monteith equation, Modified Penman, Blaney-Criddle, Hargreaves, Priestley-Taylor and the Markkink indirectly. Applying several methods to calculate crop water requirements, the results of every ten days were evaluated by correlation analysis. The data measured in 2006 proved regression equations and the accuracy is higher.