Optimal Allocation Of Soil And Water Resources Based On Synergistic Agricultural Surface Pollution And Economic Benefits In A Changing Environment

Agricultural water and soil resources are very important for human production and life.However,due to uneven distribution and unreasonable utilization,agricultural sustainable development and food security are facing serious threats.A reasonable comprehensive allocation of agricultural water and soil resources is the key to determining agricultural production efficiency and ensuring food security.As population growth and the amount of available soil and water resources continue to decrease,the comprehensive allocation of agricultural soil and water resources is increasingly pursuing diversified development.On the one hand,the growth of agricultural economic efficiency means that more fertilisers and pesticides need to be invested to stimulate the increase of crop yields,and the improper application of fertilisers will lead to agricultural surface pollution;on the other hand,the increase of food production will consume a large amount of soil and water resources,thus increasing the shortage of resources.At the same time,climate change and human activities will exacerbate the conflict between the water and soil resources-economic benefits-environment subsystem.Therefore,effective reduction of agricultural pollutant emissions and consumption of soil and water resources,while ensuring economic efficiency growth,are important factors in promoting sustainable agricultural development.This study takes Heilongjiang Province as the study area and constructs an integrated optimal allocation model of agricultural soil and water resources at three scales:farmland,single irrigation area and large area agricultural irrigation area,respectively,in order to weigh the contradictions between multiple objectives of soil and water resource use efficiency,economic benefits and environmental effects,and to reflect the impact of changing environment on the sustainable optimal regulation of agricultural soil and water resources.The main research contents and conclusions are as follows.(1)Synergistic regulation of agricultural water and soil resources at the farm scale:the modern agricultural high-tech demonstration park in Harbin,Heilongjiang Province,was used as the study area.Dynamic Bayesian prediction of ET_o,field monitoring and indoor experimental analysis were used to quantitatively characterise total nitrogen and total phosphorus of crops and soils in the farmland.Dual interval numbers were used to reflect the dual uncertainty of experimental data and hydrometeorological data.The results show thm2t the higher the delay order of the dynamic Bayesian network,the more accurate the prediction;ET _o is significantly driven by meteorological factors,when the average temperature is reduced by 10%,ET_o is reduced by 1.36%,the required irrigation water is reduced by 4.9%,and the economic efficiency will be increased by0.79%;the pollutant emission is reduced by 12.80%,and the synergy of the sys tem is increased by23.2%.(2)Synergistic regulation of agricultural water and soil resources at a single irrigation district scale:the Jinxi Irrigation District in Heilongjiang Province was used as the study area.A non-point source pollution input-output model,a one-dimensional water quality model and an economic efficiency function coupling were used.A fuzzy method was used to solve the optimisation model,and water supply uncertainty under climate chm2nge was quantified by Bayesian methods and interval linear regression.The results show thm2t by adjusting the acreage of rice,maize and soybean,the hm2rmony level is increased by 10.7%compared to the status quo;and the pollutant emissions of maize and soybean are reduced by 24.7%and 3%respectively compared to the actual cropping pattern.The output coefficients for nitrogen and phosphorus pollutants were reduced by20%compared to the standard for optimal output.(3)Large agricultural irrigation area scale:37 agricultural irrigation areas in the Sanjiang Plain of Heilongjiang Province were used as the study area.An economic efficiency function with coupled fairness is used to quantitatively characterize the discharge of agricultural pollutants through an improved input-output model,balance the contradiction between water saving and yield increase through irrigation water use efficiency,quantify the stochastic uncertainty of water supply using a Bayesian network combined with a climate change model,reflect the fuzzy uncertainty of input parameters through intuitive fuzzy numbers,and then construct a stochastic fuzzy double uncertainty based The model is then constructed based on stochastic fuzzy double uncertainty of the synergistic optimal allocation of water and soil resources in large agricu ltural irrigation areas,and a fuzzy mathematical method of optimistic-pessimistic-hybrid view is used to solve the model.The results show that the optimized TN emissions are 17.6%less than the status quo,and the TP is not much different from the status quo.The optimized water consumption per unit area is6509.15m~3/hm~2,which is 7.4%and 8.6%lower than the status quo and planning respectively.Compared with the actual and planned situation,the irrigation water use efficiency has improved by 1%and 1.4%respectively.