长江上游地区畜禽粪尿耕地承载负荷估算及风险评价

Carrying load estimation and risk assessment of cultivated land for livestock and poultry manure in the upper reaches of the Yangtze River

  • 摘要: 为评估长江上游地区畜禽粪尿耕地承载负荷及风险状况,从种养结合的角度,采用2022年国家及地方统计年鉴和统计公报数据,结合第二次全国污染源普查畜禽饲养期产污系数及各地实际耕地面积,对该地区畜禽粪尿、总氮和总磷的耕地承载负荷进行估算和风险评价。结果表明:2021年长江上游地区畜禽粪尿产生量为47 347.97万t,其中氮、磷含量分别为228.05万、40.90万t;牛粪产生量为29 277.36万t,占总量的61.83%,是整个区域的主要污染物来源,四川是畜禽粪尿产生量最大的省份,为13 474.57万t,占总量的28.46%;耕地氮、磷负荷分别为135.71、24.34 kg/hm2,为欧盟粪肥年施氮、磷量标准限值的79.83%、69.54%;从畜禽养殖氮、磷耕地承载指数来看,四川、重庆、贵州、云南可增加养殖数量,而西藏、青海仅以耕地对畜禽粪尿进行消纳存在较大污染风险,需拓展多元土地消纳路径;长江上游地区畜禽养殖土地承载力为24 762.54万头猪当量,畜禽养殖发展潜力为2 871.91万头猪当量,但分布极不平衡,仅基于耕地消纳来看,四川是区内畜禽养殖进一步扩容的主体。因此,长江上游地区应根据各地实情因地制宜,强化肥料化利用,拓展能源化、饲料化等途径,多举措协同,实现畜禽粪尿的综合治理与高效利用。

     

    Abstract: This study assessed the cultivated land carrying loads and risks of livestock and poultry manure in the upper reaches of the Yangtze River from an integrated crop-livestock farming perspective. Using data from the 2022 national and local statistical yearbooks and statistical bulletins, along with the pollutant generation coefficients during the livestock and poultry breeding period from the Second National Pollution Source Census and the actual cultivated land area in various regions, we estimated the cultivated land carrying loads of livestock and poultry manure, total nitrogen and total phosphorus in this region and conducted a risk assessment. The results showed that in 2021, the total livestock manure generation reached 473.48 million tons (Mt), with nitrogen (TN) and phosphorus (TP) contents of 2.280 5 and 0.409 0 Mt, respectively. Cattle manure dominated at 292.77 Mt (61.83% of total), while Sichuan Province contributed the largest share (134.75 Mt, 28.46%). The nitrogen and phosphorus loads on cultivated land measured 135.71 and 24.34 kg/hm2, reaching 79.83% and 69.54% of the EU's annual application limits for organic fertilizers, respectively. Cultivated land carrying indexes of nitrogen and phosphorus from livestock and poultry breeding indicated that Sichuan, Chongqing, Guizhou and Yunnan possessed potential for controlled livestock expansion, whereas Xizang and Qinghai faced high pollution risks due to reliance solely on cultivated land for manure assimilation, necessitating diversified land-based approaches. The theoretical land carrying capacity was calculated at 247.63 million pig equivalents in the upper reaches of the Yangtze River, with a developmental deficit of 28.72 million pig equivalents, but the distribution was extremely uneven. When viewed solely based on cultivated land consumption, Sichuan shouldered the main responsibility for further expanding livestock and poultry farming within the region. To address these challenges, region-specific strategies should prioritize fertilizer-oriented manure utilization while expanding energy conversion and feed production pathways. An integrated approach was critical to achieving comprehensive manure management and sustainable resource utilization in the upper reaches of the Yangtze River.

     

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