基于SD模型的诸城市农业结构仿真优化研究

［目的］预测2017—2035年诸城市农业结构的变化趋势，对农业结构进行多情景优化仿真，提出优化调整建议。［方法］文章以山东省诸城市作为研究对象，将农业结构划分为种植、种养结合和加工休闲3个子系统，选取56个指标，运用多元统计回归分析等方法构建41个方程，建立农业结构系统动力学（System Dynamics，简称SD）模型，运用Vensim—PLE软件进行仿真优化分析。［结果］SD模型预测结果表明，到2035年，粮食作物播种面积1105万hm2，总产量8037万t，经济作物播种面积652万hm2，总产量15203万t； 生猪出栏量达到29615万头，家禽出栏量1105 231亿只，畜禽粪污利用率8792%； 农业总产值达到25132亿元，休闲农业产值6134亿元，食品加工业产值1 25263亿元。假设种植业生产中的农业科技投入增加2个百分点， 2035年粮食作物产量较优化前增加576万t； 经济作物产量较优化前增加2814万t； 假设有机肥施用补贴增加3个百分点， 2035年畜禽粪污利用率较优化前提高762个百分点； 假设农产品加工业的研发力度和科技投入增加1个百分点， 2035年食品加工产值较优化前增加73521亿元； 农产品加工业产值占农业总产值比值由优化前的325：1达到41：1。［结论］为进一步推进诸城市农业结构调整，迫切需要加大农业科技投入，完善有机肥扶持政策，培育种养结合新型经营主体，重点扶持培育加工龙头企业，发展现代化休闲农场，促进农业产业融合发展。

SIMULATION AND OPTIMIZATION OF AGRICULTURAL STRUCTURE IN ZHUCHENG BASED ON SYSTEM DYNAMICS

This paper predicts the trend of agricultural structure from 2017 to 2035, carries out multi scenario optimization simulation of the agricultural structure and provides recommendations for optimizing the adjustment of agricultural structure in Zhucheng city (Shandong province). In building the agriculture system dynamics model, the agricultural structure was divided into three subsystems, namely planting, planting and breeding as well as processing and leisure. The model contained 56 indicators and 41 equations constructed using multivariate statistical regression analysis. Simulation optimization analysis of the model was performed by using Vensim PLE software. The simulation results of the model indicated that by 2035, the area planted with grain crops would be 110,500 hm2 with a total output of 803,700 tons whiles the area planted with economic crop would be 65,200 hm2 plus 1,520,300 tons as the total output. The total number of pigs and poultry recorded 2,961,500 and 110,523,100 respectively with the utilization rate of livestock and poultry reaching 87.92%. In addition the output values of leisure agriculture and food processing industry amount to 6.134 billion yuan and 125.263 billion yuan respectively whereas agricultural productivity amount to 25.132 billion yuan. This paper assumed that agricultural science and technology investment in crop production would increase by 2% with grain crop yield reaching 861,300 tons recording an increase of 57,600 tons in 2035, economic crop yield would reach 281,400 tons whilst organic fertilizer subsidies would increase by 3%. It is estimated that the utilization rate of livestock and poultry manure would reach 98.6% in 2035, which was 7.62% growth before optimization. In addition, the research and development efforts and technology investment of agricultural products processing industry increased by 1%. By 2035, the value of food processing increased by 73.521 billion yuan compared with optimization, with a growth rate of 58.69% this recorded a total agricultural output value of 25.132 billion yuan; compared with 3.25:1 before optimization, the ratio of the output value of agricultural products processing industry to the total agricultural output value reached 4.1:1.In order to further promote the adjustment of agricultural structure in Zhucheng city, the region urgently needs to increase investment in agricultural science and technology, improve on existing policies for organic fertilizers as well as foster new agricultural business entities of crop animal mixed farming system. There is also the need to support the development and processing of leading enterprises and development of modern leisure farms coupled with promote the integration and development of agricultural industries in Zhucheng City.