Research On Prevention And Control System Of Livestock And Poultry Excreta

In line with pollution condition of livestock and poultry excreta in Jiangsu province, dynamic model of control on agricultural system of livestock and poultry excreta was built with circular economy idea as key point by using of safety economic bearing-capacity on field's livestock and poultry excreta as well as ecological treatment of breeding sewage; control on agricultural system of pollution by livestock and poultry excreta in Heheng village of Jiangyan City was simulated by using of MatLab and computer simulation; strategies of prevention and control were put forward from the point of system. The main research contents and results are as follows:1. Safety economic bearing-capacity on field's livestock and poultry excretaField-experiment was adopted to conduct research on the capability of rice and barley absorbing N and P. We analyzed the livestock and poultry deject disposal capability of crop by determining and estimating losing amount and ratio of N and P in soil. The result showed that, in a certain range, amount of crop absorbing N and P rose with increasing of livestock and poultry deject using. But there was no significant difference between each treatment, which means losing amount and ratio of N and P increased by times with increase of livestock and poultry deject using. Crop absorbed 368.4kg/hm2 N and 81.98kg/hm2 P from soil at most in one year, under 34.6t-hm-2 pig feces using amount per year was suitable to prevent secondary pollution that caused by the influx of excessive N and P to around water system. Basing on the analysis of production value of different fertilizer using amount,60-120 t·hm-2 per year was optimal. Therefore, considering integrated factors including ecological environment and fertilizer using ratio as well as yield, the safety economic_bearing-capacity on field's livestock and poultry excreta was 35-60 t·hm-2·a-1·a pig feces equivalent on the precondition that no other fertilizer was used.2. Evaluation on pollution load of livestock and poultry excreta in Jiangsu provinceDevelopment of raising industry in Jiangsu province consisted of two phases. During the first speed development phase from 1997 to 2003, breeding scale of Suzhou and Wuxi in 2003 expanded 346%and 300%compared to 1997, respectively, even 44%in least expanded Nantong. In adjustment phase after 2003, breeding scale in Changzhou, Nantong, and Zhenjiang increased in small range, while declined in 10 cities like Nanjing, Wuxi and Suzhou. Wuxi's 46.75t/hm2 ranked the foremost real load of farmland livestock and poultry excreta in 2006, following as Nanjing (41.59t·hm-2) and Suzhou (34.44t·hm-2). Load value around 20t·hm-2 of Huaian, Yangzhou, Zhenjiang and Suqiang were relatively lower than that of other cities.Pollution load of each city in Jiangsu province were evaluated with 60 t·hm-2 as the alarm value of the safety economic bearing-capacity on field's livestock and poultry excreta. Results showed that environment of Wuxi(0.78) was in danger with livestock and poultry excreta volume, Huaian(0.31), Yangzhou(0.34), Zhenjiang(0.34), Suqiang(0.34) and Lianyungang(0.38) were out of danger and the rest cities were in less polluted position.Pollution load of livestock and poultry excreta of overall Jiangsu province in 2006 was 28.59t·hm-2, warning value was 0.47, being in less threatened position.3. Technology of ecological treatment on sewage of breeding of livestock and poultryTreatment combined with grain straw and hydrophytes was adopted to purify breeding sewage in this study.Under laboratory conditions, livestock excrement waste water was purified by adsorbing on 4 different length Straws of wheat. The results showed that they have interception rates 10-20%, among which absorption of N and P in layer form was better than those of in whole, fracture, or ground form. When using the layer form, the optimum treatment time is 90 min, at which point the best absorption quantity of total N and total P in per Kg straw are 286.42mgand 110.81mg respectively.Four hydrophytes, Eichhornia crassipes, Alternanthera philoxeroides, Vetiveria zizanioides and rice, were planted in breeding solid water to research their purification capacity. The result showed that purification ratio of Eichhornia crassipes, Alternanthera philoxeroides, Vetiveria zizanioides and rice were 76-90%,51-65%,42-67% and 66-88%, respectively in 30 days. The purification capacity of these 4 hydrophytes was arranged as follow:Eichhornia crassipes> rice> Alternanthera philoxeroides> Vetiveria zizanioides. In high concentration sewage (97.3mg·L-1 N,39.7mg·L-1 P) absorption, the increasing ratio of Eichhornia crassipes, Alternanthera philoxeroides, Vetiveria zizanioides and rice were 82.1%,37.5%,-3.2%and 4.6%, respectively in 30 days, which showed that Eichhornia crassipes was suitable for purifying high concentration solid water while Vetiveria zizanioides was not.The experimental in 30 days showed that when the biomass of rice, Eichhornia crassipes, Alternanthera philoxeroides increased 1Kg, the mean purification quantity of total NP were 48g,2.9g,2.5g respectively.4. Control simulations of Agricultural System of livestock and poultry excretaBased on the study of safety economic bearing-capacity on field's livestock and poultry excreta as well as ecological treatment of breeding sewage, researches such as optimizing construction, parameter and performance of simulation model and self-motion were conducted with MATLAB and computer simulation by using dynamic model, process hypothesis, and system analysis. System simulation was experimented by optimizing construction and parameter of control model of agricultural system of livestock and poultry excreta in Heheng village when hypothesized 6 State Variables, an ideal working-point-value of system, basic year 2007 for comparison. The results showed that the system had become an ideal Stability state from an unsatisfied initial-value when experienced less than 20 years and little fluctuation, that is to say, the development of Heheng village can reach a requirement of sustainable development before 2027.Text of model efficiency by earlier data(1991-2007) of Heheng village demonstrated that it is feasible to establish the control model of agricultural system of livestock and poultry excreta (R2min=0.8, R2max=0.94, v=0.855, n=6).Compared to optimizing system, economic index in 2030 predicted by former model system declined significantly, breeding scale of former system was smaller than optimizing system, and crop yield reduced 15%. On the precondition of 5.6%reduction of breeding scale, NP in water of former system was 14 times higher than optimizing system. Development system without ecological project brought less economic interests and more environmental pollution, which couldn't meet requirement of circular agriculture. On the other hand optimizing system with ecological project was an ideal development model that met requirement of sustainable development.5. Investigation and Analysis of Behavioral Factors of Agricultural Non-point Source PollutionThe problems and factors existing in rural environment of Gaocun, Jiangyin, jiangdu, jiangyan, Funing, Guannan in Jiangsu were analyzed by the on-site investigation and the informal discussion meeting. The results showed that factors of agricultural non-point source pollution in Mid-Jiangsu or north-Jiangsu were relation with socioeconomic, especially the absence of environment protection and Economic aggregate in north-Jiangsu.Questionnaires covering 195 farmers showed that all the farmers used chemical fertilizer, only 62.3%farmers preferred organic manure.29%farmers abandoned livestock and poultry excreta,61%farmers returned them to fields,10%farmers sold them to organci fertilizer factory.62.1%farmers thought government should be responsible for rural environmental control,33.8%farmers thought it is enterprise's responsibility,49.1%, only 4.1%farmers thought it is them-selves responsibility. The above results showed that government should abandon the main responsible for rural environmental control.4%farmers were un Willingness to pay for environment protection; 46.9%farmers depended on the pay situation is; 49.1%farmers were Willingness to Pay for environmental control, of which the highest bearing pay is about 2%total annual income and the mean pay is about 0.798%total annual income. The correlation between farmer's environmental awareness and average net income per year was 0.928, and the correlation between environmental awareness of rural residents and their educational level was 0.94 that higher than correlation of their income level. Therefore, several measures, such as developing local economy, enhancing environmental education, raising people's educational level, would make farmers be willing to protect environment, which was important to control livestock and poultry excreta pollution.6. Strategies of prevention and control on pollution of livestock and poultry excretaBased on the pollution factors of livestock and poultry excreta, the behaviors analysis of farmers'environmental protection, and the control simulations of agricultural system, strategies of prevention and control on pollution of livestock and poultry excreta of "policy-guidance, scale-harmonious, matching-technology, mechanism-perfection" were put forward from the point of system dynamic.