Regional Environmental Carrying Capacity for Livestock and Poultry Breeding Based on Planting-breeding Balance in Hangzhou City
2016, 31 (8):
Taking available nitrogen and phosphorus in soil, and annual statistical data of planting and breeding as data sources, and using modified nutrient-balance method, the environmental carrying capacity and pollution risk of livestock and poultry breeding in Hangzhou City was explored. Firstly, it is found that the amount of nitrogen and phosphorus consumption of main crops in Hangzhou were 39 886.4 and 21 874.1 t in 2014. Vegetable, rice, fruit and beans consumed 11 879.7, 8 588.2, 5 255.0 and 4 641.6 t of nitrogen, respectively. Meanwhile, vegetable, rice and fruit also consumed 10 394.8, 4 480.8 and 2 189.6 t of phosphorus, respectively. Secondly, the strongest counties of soil nitrogen and phosphorus supply were Lin’an (86.6 kg/hm2 for nitrogen) and the downtown area (60.6 kg/hm2 for phosphorus), while the weakest one was Tonglu County (77.0 kg/hm2 for nitrogen and 59.2 kg/hm2 for phosphorus). Thirdly, during 2014, the environmental carrying capacities of districts in Hangzhou ranged from 1.48 to 35.59 heads/hm2, and 1.01 to 39.79 heads/hm2 when calculated on the basis of nitrogen and phosphorus, respectively. According to the environmental carrying capacity of livestock and poultry breeding, all the counties of Hangzhou City could be divided into three levels. Fuyang was on the highest level with carrying capacity of 35.59 (based on nitrogen) and 39.79 head/hm2 (based on phosphorus). Yuhang, Xiaoshan, and Jiande were on the second level with carrying capacities ranging from 20 to 30 head/hm2. Tonglu, Lin’an, Chun’an and the downtown area were on the lowest level with carrying capacities all below 10 head/hm2. Fourthly, the pollution risk indices in livestock manure ranged from 0.19 to 8.05 (based on nitrogen) and 0.14 to 11.68 (based on phosphorus). These results indicated that the pollution risk of livestock manure in Hangzhou was generally low. However, the pollution risk in each district was significantly different. Environmental carrying capacities of the downtown area and counties of Lin’an, Chun’an and Tonglu were severely overburdened, while Fuyang, Yuhang, Xiaoshan and Jiande had not exceeded their environmental carrying capacity. Overall, the areas with high pollution risk of livestock manure needed to reduce the scale of breeding urgently and transfer the redundant manure to surrounding counties that still have potential carrying capacity. Besides, regions having rich woodland resource also can take the wood land as disposal site to load livestock manure. As a result, more detailed data is in urgent needed to achieve more scientific and accurate results so as to provide scientific basis for layout planning and pollution regulation of livestock and poultry breeding industry in Hangzhou.
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