Irrigation Management For Winter Wheat Based On Aquacrop Model

AquaCrop model published by FAO(Food and Agriculture Organization) in 2009 is a new simple and practical crop model that using the less data to predict the crop productivity and soil water and simulate the crop growth.This study used the AquaCrop model to predict the yield of winter wheat from 2012 to 2013 based on the daily meteorological data and the soil parameters and crop growth data and a series of management data in the experimental fields of key laboratory of soil and water conservation engineering irrigation experimental station, Yangling, Shaanxi province.At the same time, the productivity of winter wheat from 2011 to 2012 was validated and assessed by using the AquaCrop model. Secondly, to research effect of different ways and different time of irrigation to winter wheat yield and water use efficiency, and then optimize the irrigation management system. The main results and conclusions have been drawn from this study as follows:(1) By debugging this model, a series of model parameters in Yangling district were obtained: planting density of winter wheat is 280000 Plant/ha; from seeding to emergence wheat needed 9 days; the largest canopy coverage is 96%; it is 196 days that wheat grew to maximum canopy coverage, the canopy decline coefficient is 9.8%, it needed 200 days from seeding to flowering and 211 days from sowing to aging time; flowering period is 8 days; the depth of maximum and minimum effective root are 3m and 0.3m respectively; it is 200 days to the deepest root; reference harvest index is 48%.(2) After debugging and calibrating the AquaCrop model, this model can highly simulate the yield of winter wheat, aboveground biomass and biomass of growth period in Yangling region. In this study, the adjusted determination coefficient(R2) between simulated canopy cover and measured canopy cover was 0.99,and both in the whole growth period of root mean square error(RMSE) in the process was 4.7%, the standardized root mean square error(NRMSE)is 5.3% and conformity index being 0.97; the finally the relative error between the measured value and simulated value of winter wheat yield was-1.37%; relative error between the ground biomass finally and the simulation value of is 4.97%; The root mean square error(RMSE) between biomass of winter wheat in the whole growth period and the simulated value is 1.33t/ha, and the root mean square error(NRMSE) is 14.6%; the conformity index being 0.99. This result.fully demonstrated AquaCrop model can apply to this region, Shaanxi province.(3) Comprehensively considering the production and the water use efficiency, this research develop appropriate amount of deficit irrigation in different years which is in different water content. In wet years, it needs 50 mm in the green returned stage or jointing stage. In a normal year we need two times irrigation(100mm):50 mm in the green returned stage and jointing stage respectively. In dry years we need three times irrigation(150mm): 50 mm in the green stage, jointing stage and milking stage separately.