基于种养平衡的成都市畜禽养殖环境效应分析

目的]文章以成都为实例,旨在科学估算畜禽养殖产排污总量和耕地承载负荷,准确评价畜禽养殖潜在环境风险状态。方法]通过收集成都市农业统计数据,依据我国有关畜禽的产排污系数,根据计算公式估算了2015年成都畜禽养殖粪便、粪便氮和粪便磷的产生量,估算了成都各区(市)县畜禽粪便、粪便氮和粪便磷的耕地承载负荷和警报值,采用畜禽粪便耕地负荷警报值分级方法评价了畜禽粪便、粪便氮和粪便磷的潜在环境风险状态。结果]2015年成都畜禽粪便、粪便氮和粪便磷的产生总量分别为1 031.90万t、5.69万t、1.09万t,其中生猪粪便、粪便氮和粪便磷的产生量分别为707.49万t、3.24万t、0.77万t,贡献率最大,为65.51%,其次分别为家禽20.25%,牛8.63%,肉兔2.96%和肉羊2.65%;全市平均畜禽粪便、粪便氮和粪便磷的耕地承载负荷分别为20.40t/hm~2、112.51kg/hm~2、21.47kg/hm~2,均低于耕地负荷限量值,警报值均低于0.7,属于Ⅱ级,处于低风险状态,环境容量总体可接受,但大邑县、新津县和邛崃市略超耕地负荷限量值,存在微超载现象。结论]2015年成都畜禽养殖粪便、粪便氮、粪便磷的耕地承载负荷总体上处于低风险状态,其中有8个区(市)县处于无风险状态,7个区(市)县处于低风险状态,2个区(市)县处于中等风险状态,3个区(市)县处于较高风险状态,没有出现高风险和极高风险状态的区(市)县;从区域布局来看,西南片区有3个区(市)县养殖比重稍大,应该果断调减养殖量;针对成都市畜禽养殖潜在环境风险状态,提出降低环境风险的对策建议,可为成都市调整优化畜禽养殖区域布局,制定畜禽养殖污染防治规划和政府宏观决策提供科学参考。

ANALYSIS OF ENVIRONMENTAL EFFECT OF LIVESTOCK AND POULTRY BREEDING BASED ON PLANTING-BREEDING BALANCE IN CHENGDU

The purpose of this paper was to provide scientific evaluation for the total pollution discharge of livestock and poultry breeding and carrying capacity of farmlands, and accurately evaluate the potential environmental risks of livestock and poultry breeding in Chengdu. On the basis of the agricultural statistic data of Chengdu and the pollution discharge coefficient of livestock and poultry in China, the amounts of manure, fecal nitrogen and fecal phosphorus in livestock and poultry in Chengdu in 2015 were estimated by formula, and the cultivated land carrying capacity and warning value of livestock and poultry manure, fecal nitrogen and fecal phosphorus was analyzed for each district (city) and county. Furthermore, with the grading method of warning value of farmland load, it evaluated the potential environmental risk of livestock and poultry manure, fecal nitrogen and fecal phosphorus. The results showed that the amount of livestock and poultry manure produced in Chengdu in 2015 was 103.19 million t, containing total nitrogen of 0.0569 million t and total phosphorus of 0.0109 million t. Among them, the production of pig manure, fecal nitrogen and fecal phosphorus were 7.0749 million t, 0.0324 million t and 0.0077 million t respectively, with the largest contribution rate of 65.51%, followed by poultry, cattle, rabbit and sheep of 20.25%, 8.63%, 2.96% and 2.65% respectively. The average manure load, nitrogen load and phosphorus load were 20.40 t/hm2, 112.51kg/hm2, 21.47kg/hm2 respectively, which were lower than the limit load value of cultivated land and the warning value of 0.7. It belonged to the second grade and was in a low risk state. The overall environmental capacity was acceptable. However, Dayi, Xinjin and Qionglai slightly exceeded the load limit value. The results suggested that the carrying capacity of livestock and poultry manure, fecal nitrogen and fecal phosphorus of cultivated land in Chengdu were at a low risk as a whole in 2015. There were 8 districts or counties without risk, 7 districts or counties at low risk, 2 districts or counties at medium risk, 3 districts or counties at relatively higher risk, there was no district or county at high or extremely high risk. From the angle of the regional layout, there were 3 districts or counties in southwest area with slightly larger proportion of breeding which should decisively reduce the amount of farming. Targeting at the potential environmental risk in livestock and poultry breeding in Chengdu, it put forward some suggestions for providing a reference for the city to adjust and optimize its regional planning of livestock and poultry breeding regions, formulate preventative planning and macro-governmental decisions.