Long-term simulation of growth stage-based irrigation scheduling in maize under various water constraints in Colorado, USA

摘要

Due to varying crop responses to water stress at different growth stages,scheduling irrigation is a challenge for farmers,especially when water availability varies on a monthly,seasonal and yearly basis.The objective of this study was to optimize irrigation between the vegetative (V) and reproductive (R) phases of maize under different available water levels in Colorado.Long-term (1992-2013) scenarios simulated with the calibrated Root Zone Water Quality Model were designed to meet 40％-100％ of crop evapotranspiration (ET) requirements at V and R phases,subject to seasonal water availabilities (300,400,500 mm,and no water limit),with and without monthly limits (total of 112 scenarios).The most suitable irrigation between V and R phases of maize was identified as 60/100,80/100,and 100/100 of crop ET requirement for the 300,400,500 mm water available,respectively,based on the simulations from 1992 to 2013.When a monthly water limit was imposed,the corresponding suitable irrigation targets between V and R stages were 60/100,100/100,and 100/100 of crop ET requirement for the above three seasonal water availabilities,respectively.Irrigation targets for producing higher crop yield with reduced risk of poor yield were discussed for projected five-year water availabilities.