| Converting Cropland to Forestry and Grassland (CCFG) is one of very important stratagems of state government. The implement of CCFG not only improves the environment, but also speeds sustainable development of agriculture. In order to enhance integrate benefit of CCFG, the optimum adjustment of agricultural production structure and crop structure is very important. Based on estimation of resources production potential, and analysis of agri-ecology systems and its energy input, an optimum agricultural production structure was put forwarded by using the methods of linearity programming. The main results are as follows:(1)In the research area, climatic production potential of alfalfa, corn, millet, wheat and soybean are 40946.70kg/hm,9586.47 kg/hm~2,5969.15 kg/hm~2,6380.13kg/hm~2 and2860.00 kg/hm~2, respectively on table land, while those on slope land, are37092.89 kg/hm~2, 8537.95 kg/hm~2,8537.95 kg/hm~2,5752.58 kg/hm~2, 2640.00 kg/hm~2 respectively. It could be concluded that the climatic potential production of different crops on table land was higher than that on slope land. Actual accumulative temperature and precipitation of alfalfa are 0.71% and 0.85% of demand, respectively, which is higher than other crops; Alfalfa's climatic production potential using rate on table land and slope land were 32.77% and 32.15% respectively, which were lower than those of other crops. Therefore, it indicated that alfalfa had a higher potential production. However, the potential production exploitation degree of the alfalfa on the research sites is lower at present.(2) The average input of matter to agri-ecosystem in the research area is 269.39 kg/hm~2 and 139.00 kg/hm~2 on table land and slopes, its output is 108.41 kg/hm~2 and 46.73 kg/hm~2,respectively.The matter input to agri-ecosystem of table land is 1. 48 times higher than that to slope land, and the output from agri-ecosystem of table land is 1.97 times higher than that from slope land; The ratio of output and input on table land and slope land are 0.37 and 0.34, respectively, 10.81% higher on the TL than on the SL . The average input of energy to agri-ecosystem in the research area is 76.4 MJ/hm~2 and 30.08 MJ/hm~2 on table land and slopes, its output is 88.61 MJ/hm~2 and 60.31 MJ/hm~2 ,respectively, The energy input to agri-ecosystem of table land is 1.53 times higher than that to slope land, and the output from agri-ecosystem of table land is 0.47 times higher than that from slope land; The ratio of output and input on table land and slope land are 0.76 and 2.19, respectively, 188.16% higher on the SL than on the TL. The average input of value to agri-ecosystem in the research area is 1505.3 Yuan /hm~2 and 754.7 Yuan /hm~2 on table land and slopes, its output is 4826.1 Yuan /hm~2 and 3232.3 Yuan /hm~2 ,respectively, The value input to agri-ecosystem of table land is 0.99 times higher than that to slope land, and the output from agri-ecosystem of table land is 1.15 times higher than that from slope land; The ratio of output and input on table land and slope land are 3.31 and 4.28, respectively, 33.33% higher on the SL than on the TL. Thereby, table land agri-ecosystem has high input , high output and low using efficiency; slope land agri-ecosystem has low input,low output and high using efficiency.(3) After the CCFG, the net energy value output of agri-ecosystem was enhanced by 35.14%, and the environment burthen was reduced by 8.31%, the system sustainable development index was increased by 47.38%, the system stability index was elevated from 0.809 to 1.015. Obviously, agri-ecosystem productivity and agri-ecological environment were all improved by CCFG, and CCFG is also benefit to sustainable development of the agri-ecosystem. Therefore, the government should increase its implementation consistently. After CCFG, the coupling degree between farming system and livestock system was reduced by 41.74%, which indicated that the development of cropping and animal raising is unbalanced .Resources advantages was not transformed to economical advantages. Departments of livestock and veterinary should guide the farmers applying intensive cultivation, better varieties, warm sheds, deciding livestock number by grass carrying capacity, expanding animal raisin scale, in order to achieve balanced development between cropping and livestock husbandry.(4) linear programming method was used to plan and adjust the agricultural production structure. The optimization results of agriculture ecosystem structure are as follows: the cropping area of wheat, corn, millet, pearl millet, soybean, rape, rape is 14.04 hm~2, 5.93hm~2, 0.49hm~2, 0.00hm~2, 0.12hm~2, 0.85hm~2, 17.45hm~2, respectively. The number of cow, sheep, pig, chicken is 88.98, 270.68, 91.07, 918.96, respectively. After the optimization, the cropping area of wheat, millet, pearl millet, soybean, rape reduced by 4.30%, 80.67%, 100.00%, 5.23% and 78.03%, respectively .And that of corn and alfalfa increased by 45.59% and 367.37% respectively. The number of cattle, sheep, pig and chicken increased by 71.12%, 68.13%, 167.84% and 116.74%, respectively. According to the results mentioned above, the net income of the whole village amount to 408,826 RMB Yuan, which was 2.05 times that of in 2005. The optimization result coordinated development between cropping and animal raising with higher efficiency of economy, social and the ecology. |
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