湖南省畜禽养殖粪污的耕地负荷与土地承载力评价

Evaluation of Farmland Load and Land Carrying Capacity of Livestock and Poultry Manure in Hunan Province

[目的]测算和分析畜禽养殖粪污耕地负荷和土地承载力,为防治农业面源污染,促进农牧协调发展提供科学依据。[方法]根据湖南省畜禽养殖、作物产量等数据资料,在考虑粪污综合利用率的前提下,采用产排污系数法、养分平衡法分别计算2020年各地市州畜禽养殖耕地污染负荷和土地承载力,分析畜禽养殖空间布局以及粪污消纳分配。[结果]湖南省2020年共养殖猪当量4.27×10^(7)头,各区域养殖量差异很大;畜禽粪便和TN,TP耕地负荷分别为19.04t/hm^(2),94.85,24.99kg/hm^(2),耕地负荷警报级别均在Ⅱ级以上,对耕地环境稍有威胁,其中永州市、娄底市、怀化市、郴州市至少有两项耕地负荷警报级别达到了Ⅲ级及以上,耕地环境风险较高;畜禽养殖土地最大承载量为1.23×10^(8)头猪当量,已养殖猪当量仅占其37.18%。各地市州的可增加养殖量也非常可观,常德市、益阳市、岳阳市、邵阳市、长沙市、永州市、衡阳市7个市的可养殖猪当量在5.00×10^(6)头以上。在确认区域内畜禽养殖未超载的基础上,永州市、娄底市、怀化市、郴州市要鼓励林地、园地的作物管理者增加有机肥的施用比例,加大粪污消纳量,才能降低耕地环境污染风险。[结论]湖南省畜禽养殖耕地环境风险整体上较低,畜禽养殖业发展空间很大,但是部分地市州存在耕地污染风险,必须调整粪污消纳去向,才能缓解耕地的粪污消纳压力,推动农业可持续发展。

[Objective]The purposes of this study were to provide a scientific foundation for the prevention and control of agricultural non-point source pollution,and to promote coordinated development between agriculture and animal husbandry by calculating and analyzing livestock manure load of farmland and land carrying capacity.[Methods]We considered the comprehensive utilization rate of livestock and poultry waste,and employed the method of the pollution generation and discharge coefficient and the method of the nutrient-balance to separately calculate livestock manure load of farmland and land carrying capacity in different regions of Hunan Province in 2020.The spatial layout of livestock and poultry breeding and the distribution of manure pollution were analyzed by utilizing data regarding livestock manure and crop yield in Hunan Province.[Results]A total of 4.27×10^(7)pigs were bred in Hunan Province in 2020,with significant variation across regions.The loads of livestock and poultry manure,TN,and TP on farmland in Hunan Province were 19.04 t/hm^(2),94.85 kg/hm^(2),and 24.99 kg/hm^(2),respectively,and the cultivated land load alert levels all exceeded levelⅡ,posing a slight threat to the farmland environment.At least two farmland load warning levels in Yongzhou,Loudi,Huaihua,and Chenzhou City reached levelⅢor above,indicating a heightened environmental risk.The maximum land carrying capacity of livestock and poultry breeding land was 1.23×10^(8)pig equivalents,but the currently raised pig equivalents only accounted for 37.18%of this value.This result indicated that there was significant potential for increasing the livestock breeding capacity in various cities,with seven cities(Changde,Yiyang,Yueyang,Shaoyang,Changsha,Yongzhou,and Hengyang City)capable of breeding more than 5.00×10^(6)pig equivalents.Given the absence of breeding overload within these regions,crop managers in woodland and orchards in Yongzhou,Loudi,Huaihua,and Chenzhou City were encouraged to increase their application of organic fertilizers and manure absorption to lower the risk of farmland pollution.[Conclusion]Overall,the risk posed by livestock and poultry breeding to the farmland environment in Hunan Province remains relatively low,suggesting substantial potential for future industry expansion.However,certain regions are facing farmland pollution risks,thus necessitating a redirection in manure disposal to lessen the pressure of manure absorption on farmland,thereby promoting sustainable agricultural development.