基于AquaCrop模型的有机稻灌溉制度优化

Optimization of irrigation scheduling for organic rice based on AquaCrop

随着人们对提高农业生产效率方法的不断探索,水稻生产模式正发生很大变化,并由化肥农药高投入的传统农业向生态环保的有机农业转变,但有机稻需耗水特性及其适宜的灌溉制度研究较少。为揭示有机稻耗水规律及不同降水年型下的灌水与产量关系,2015-2016年在湖北省漳河灌区开展了有机稻灌溉试验研究,统计分析了有机稻与普通稻的需耗水差异,获得了有机稻耗水及其产量特性,提出了基于Aqua Crop模型与熵值法耦合的有机稻灌溉制度多目标多情景优化方法。结果表明:1)有机稻与普通稻需水量无显著差异,但前者的排水量显著高于后者,且前者排水中的氮磷浓度均显著降低。有机稻产量为普通稻产量的84%,但单方灌水产值高28.5%(P<0.05),具有显著的经济效益。2)优化后中国南方灌区有机稻适宜的优化灌溉制度为:枯水年,108%(以RAW计,下同)的土壤含水率控制下限、30 mm的灌水定额、灌水8~9次,平水年113.85%的土壤含水率控制下限、32.31 mm的灌水定额、灌水6~7次;丰水年,116.92%的土壤含水率控制下限、32.31 mm的灌水定额、灌水3~4次。该文为选择节水、高产的有机稻灌溉方案提供参考。

Along with the continuous exploration in enhancing agricultural productivity,the traditional agriculture which needs high input of chemical fertilizer and pesticide is gradually turned into an ecologically and environmentally friendly organic agriculture.However,there are few studies on water consumption characteristics and irrigation schedule of organic rice.To reveal the pattern of water consumption and the relationship between irrigation and yield under different precipitation types,field experiments were carried out during the rice growth period in 2015–2016 in Zhanghe Irrigation District,Hubei Province.In 2015,the same rice variety was cultivated in different modes:1)in traditional mode,the chemical fertilizer was used;2)in organic mode,the manure was used.The irrigation schedule was similar for the both modes:to keep water depth to 20-50 mm.If the rainfall was over the 50 mm,drainage was conducted.Based on the experimental results,we analyzed the difference of water consumption between organic rice and traditional rice,and obtained information on water consumption and yield characteristics of the organic rice.Based on the results of 2015,an optimization experiment of organic rice cultivation was set up:the irrigation amount was 0,50,120,230 and 330 mm,respectively.Then we proposed a multi-objective and multi-scenario optimization method of irrigation scheduling by using AquaCrop model and entropy method.One of the treatments was used for model calibration and the others were for validation.The results showed:1)the evapotranspiration of traditional rice and organic rice from the period of steeping field and reviving to milk ripening were 420 mm and 235 mm,respectively.The drainage of organic rice and traditional rice were 99.61 and 23.75 mm,respectively.The mean TN concentration of water discharge in organic rice were lower than that in traditional rice,and the TP concentration of water discharge in organic rice were also lower than that in traditional rice.2)The yield of organic rice accounted for 84%of the traditional rice yield,plant height were 7.6%higher than that of traditional rice,the empty shell rate were 10.5%higher than of the traditional rice.3)the model measurement and simulation matched well with Nash-Sutcliffe efficiency above 0.7,relative root mean square of error 0.15-0.28,and coefficient of determination higher than 0.7,indicating that the model could simulate the yield well under different conditions.4)After optimization,the irrigation schedule of organic rice in southern China were:in dry year,the lowest limit of soil volume water content were 108%RAW(readily available soil water),irrigation quota were 30 mm,frequency of irrigation were 8 to 9 times;in normal year,the lowest limit of soil volume water content were 113.85%RAW,irrigation quota were 32.31mm,frequency of irrigation were 6 to 7 times and in wet year,the lowest limit of soil volume water content were 116.92%RAW,irrigation quota were 32.31 mm,frequency of irrigation were 3 to 4 times.The study validated the applicability of AquaCrop model in rice growth simulation and irrigation schedule optimization in China and established a method of optimizing irrigation schedule by coupling AquaCrop model and entropy method,providing technical guidance to organic rice production.