Study On Experiment And Simulation Optimization Of Water And Fertilizer Regulation Of Rice

In China,there is a problem of low fertilizer utilization rate,low water resource utilization rate,and high N and P emissions of paddy fields in rice planting,in this regard,the former people have done a lot of research on slow-release fertilizer and water-saving irrigation,but most of the studies only study the application of slow-release fertilizer or only the application of water-saving irrigation,and the combined application of slow-release fertilizer and water-saving irrigation is relatively rare.Therefore,the authors organically combined slow-release fertilizer and alternate wetting and drying(Abbreviated as AWD)irrigation,and used the method of pit planting experiment and model simulation to study the effects of different water and fertilizer conditions on rice physiology and ecology,dry matter quality and distribution,nitrogen utilization,water-saving degree and yield and its constituent factors,and selected rice yield,leaf area index and dry matter accumulation index to verify the validity of the ORYZA(V3)model,evaluated the applicability of the model under different water and fertilizer coupling conditions,and the interval days,upper limit of water layer and nitrogen application level of rice with different fertilization types under the intermittent irrigation mode were optimized by model simulation,so as to provide a basis for the practice of rice water and fertilizer management mode combining slow-release fertilizer and AWD irrigation.The main conclusions are as follows:(1)In terms of rice physiology and ecology,flood irrigation and slow release fertilizer can promote plant height growth and tillering,and effectively increase the number of effective tillers;In terms of nitrogen utilization,slow-release fertilizer can promote the total amount of dry matter of rice and the dry matter accumulation of panicles,AWD irrigation can promote the accumulation of nitrogen in the stem part of rice plants,and AWD irrigation and slow-release fertilizer can increase the yield added value caused by unit nitrogen application,that is,improve the utilization efficiency of fertilizer,thereby improving rice yield.(2)The ORYZA(V3)model has a good simulation effect on the quality of dry matter in the aboveground parts of each treatment and the quality of stems and panicle,and the dry matter quality of leaves is general.The model has a good effect on the simulation of the leaf area index and yield of rice under different water and fertilizer treatments,and the linear regression coefficients are 0.918 and 0.922,respectively.(3)Appropriate extensions of AWD irrigation days for different periods can promote yield growth.The number of intermittent days before tillering in AWD irrigation of conventional fertilizers was 5-7 days,and the yield was highest when the jointing of the pregnant panicle and the interval between the maturation period were3-5 days;Under the treatment of AWD irrigation and slow-release fertilizer,the rest period before tillering is 5-7 days,and the interval between Jointing gestational panicle stage and milk ripening is most conducive to promoting yield increase.(4)In the AWD irrigation mode,appropriately lowering the upper limit of the water layer can increase rice yield.The upper limit of the aquifer with the highest yield in the conventional fertilizer and intermittent irrigation slow-release fertilizer treatments are:the upper limit of the aquifer of the pre-tillering and jointing stages of the pregnant panicle is 20 mm,and the upper limit of the water layer of the panicle flowering and milk-ripening stage is 50 mm.(5)Under the AWD irrigation mode,the appropriate increase in nitrogen application level can improve rice yield,and the maximum yield nitrogen application level of the AWD irrigation conventional fertilizer treatment is 225 kg/hm~2,and the maximum nitrogen application level of the AWD irrigation slow-release fertilizer treatment is 270 kg/hm~2.