Simulating Water Use And Yield Of Plastic Film Mulched Spring Maize With Aqua Crop Model

Dynamics of soil moisture, farmland evapotranspiration and evaporation, growth process of rainfed spring maize were monitored continuously from 2011 to 2014 in plastic mulching and non-mulching fields on the Shouyang Dryland Agricultural Experiment Station of Ministry of Agriculture of China. At the same time, Using AquaCrop Model which developed by FAO simulating water use and yields of plastic film mulching Spring Maize to reveal the mechanism of plastic mulching enhancing maize yields. The mainly research results are follows:1. In comparison with non-mulching treatment:(a) The soil moisture content in soil depth of 120 cm of plastic mulching treatment increased by an average of 3.8%, 5.6%, 5.1% and 4.1% respectively;(b) The canopy cover of plastic mulching treatment increased by 18.2%, 14%, 15.8% and 14.9% respectively.(c) The evaporation of plastic mulching treatment was lower by 53.6%, 84.8%, 45.7% and 58.5% respectively, The evapotranspiration of plastic mulching treatment was lower by 6.4%, 16.2%, 8.8% and 12% respectively;(d) The aboveground biomass of plastic mulching treatment increased by 31.4%, 27.2%, 39.2% and 26.6%;(f) The biomass of plastic mulching treatment increased by 14.9%, 7.6%, 9.2% and 13.8% respectively; The yields of plastic mulching treatment increased by 14.3%, 12.1%, 11.9% and 14.2% respectively.2. The model parameters suitable for Shouyang region after calibration include that maximum canopy cover(96% for F and 90% for CK), root average expansion rate(2.10 cm/day), reference harvest index HI0(48%), duration of harvest index(52 d), and Shape factor for effect of water stress on root zone expansion(-6).3. The results of the sensitivity analysis showed that among all of model parameters, the days to CCx, the dates while canopy senescence starting and flowering, wilting moisture content, field capacity for soil water holding and initial soil water content had the most significant influences on the simulation result with the relative sensitivity degrees of 0.13~0.58.4. AquaCrop model could capture well the dynamics of soil water content, evaportranspiration, canopy cover and biomass accumulation. Root mean square error(RMSE) between the simulated and observed the soil water content, canopy cover, ET and the aboveground biomass of spring maize were 0.4%~1.4%, 3.6%~9.8%, 0.71~0.88 mm/d and 0.56~1.45 t/ha, respectively, and their determination coefficients of the correlation(R2) were greater than 0.86, 0.96, 0.86 and 0.97, respectively. Theses results showed that the AquaCrop model could preferably simulate the dynamic changes of soil water content, canopy cover, ET and the aboveground biomass accumulation of spring maize.5. Parameterized AquaCrop model was used to simulate spring maize productivity in 2011, 2012 and 2014. The relative error of simulated biomass and yields was less than 5.8% and 9.6%, respectively. These results pronounced that AquaCrop model could simulate well water use, growth and yield of rainfed maize with plastic film mulching in this region.