Study On Summer Maize In Tianjin Coastal Area Based On AquaCrop Model

Water resource shortage and land salinization have been the hot issues of global concern.Improving water resource utilization efficiency and effectively utilizing salinization land are the key to realizing sustainable agricultural development.The crop model has the advantage of optimizing the management of water use in the field and can meet the demand of water saving in modern agriculture.After years of research by experts at home and abroad,a variety of models adapted to different environments have been developed,among which AquaCrop model is widely used.In this paper,a two-year field experiment(2019-2020)was conducted,taking summer maize as the test crop,to study the effects of different irrigation methods on crop growth dynamics under drip irrigation.AquaCrop model was used to simulate the yield of summer maize.A total of 5 irrigation treatments were set up in the experiment,and the changes of summer corn growth dynamics,aboveground biomass,yield,soil moisture content and salt content under different irrigation treatments were studied.The parameters of AquaCrop model were estimated and optimized by using the measured data in 2019 to realize the localization of model parameters and the sensitivity analysis of parameters.The model was verified with the test data in 2020,and the applicability of AquaCrop model in Tianjin coastal area was evaluated.The main research results are as follows:(1)The growth rate of summer maize is faster in the middle growth stage,and its sensitivity to water increased.Under the same irrigation quota,the film mulching treatment is beneficial to increase the plant height,stem diameter and leaf area index of summer maize,and showed that with the increase of irrigation quota,the plant height,stem diameter and leaf area index of summer maize also increased.The growth rate of summer maize at the late growth stage is slow and the demand for water was small.The change of plant height and stem diameter of each treatment was not obvious after reaching the maximum,while the leaf area index of rainfed treatment was higher than that of other treatments.(2)Under the same irrigation quota,film mulching treatment is beneficial to biomass and yield of summer maize;Under the same irrigation method,the higher the irrigation quota,the more biomass and yield of summer maize.Logistic curve model was used to establish the aboveground biomass growth simulation equation.The fitting effect R2 of each treatment was above 0.96,EF value was between 0.95 and 0.99,RMSE was between 0.13 and 0.71.(3)Under different irrigation treatments,soil moisture content and salt content in0-60cm soil layer are significantly affected by irrigation and rainfall.Soil moisture content in0-60cm soil layer increased with the increase of soil depth.Under the same irrigation method,soil moisture content increased with the increase of irrigation quota.During the critical period of summer maize growth,the soil salt content in 0-60cm soil layer of mulching treatment was lower than that of non-mulching treatment under the same irrigation quota.(4)In the sensitivity analysis of input parameters of AquaCrop model,the maximum canopy coverageCC_x and the date whenCC_x was reached had significant effects on maize biomass and yield.(5)AquaCrop model has a good simulation effect on canopy growth,aboveground biomass and yield of summer maize,while the simulation accuracy of soil moisture content under film mulching treatment needs to be improved.In the process of model verification,the correlation coefficient R~2between simulated and measured values of green canopy coverage and aboveground biomass in growth period was close to 1,the model performance index EF was above 0.95,and the root mean square error(RMSE)of canopy coverage,aboveground biomass and yield from seedling stage to jointing stage ranged from 0.15 to 0.8.RMSE of biomass from filling stage to maturity stage was greater than 0.75.The R2 and EF values of soil moisture content were low.(6)According to the rainfall of different frequencies,normal water level year was selected and different irrigation systems were set.The parameterized AquaCrop model was used to simulate the growth of summer maize,and the optimal irrigation system was selected with the goal of maximizing the yield to realize the purpose of saving resources and increasing production,providing reference for the actual production in Tianjin coastal area.