省域农用地猪粪负荷强度时空演变分析

种养循环是解决农业面源污染，促进化肥减量化以及种植业和养殖业可持续发展的重要途径。测算并合理利用农用地粪便承载力是促进区域种养业循环的基础。为了通过种养业循环解决生猪养殖污染问题，本文运用排放系数法测算2007—2016年中国31个省（市、自治区）农用地猪粪负荷强度和承载潜力，并利用ArcGIS空间统计模型分析其时空格局演变特征，运用多元线性回归模型探讨农用地猪粪负荷强度时空分异的主要影响因素。研究结果表明：1）2007—2016年中国农用地猪粪负荷强度总体上并不高，平均值为4.148 t·hm^-2，但省际差异较大。2）负荷强度总体上呈现先增后降特征，其中，青海和西藏呈现持续上升态势，新疆呈现“降-升-升”态势，宁川黔冀4个省域呈现持续降低态势，上海等12个省域呈现“升-升-降”，重庆等6个省市呈“升-降-降”态势，内蒙古等6个省域呈现“降-升-降”态势。负荷强度整体上表现出显著的空间自相关性，自相关性呈现先减弱后增强变动态势。热点区域呈向北部、西部转移趋势。3）城乡收入比、上一年成本利润率、人均猪肉消费量、人口密度、区位、人均农作物面积、河网密度和河流截面水质优良比例等因素对农用地猪粪负荷强度产生了显著影响。其主要通过市场规律、供给-需求关系、环境承载力、养殖规制和政府政策影响负荷强度变化。4）提出根据省域负荷强度热点北移西进的态势以及各地承载潜力，制定生猪养殖业区域规划和负面清单政策，引导种养业在一定区域内实现循环耦合等政策建议。

Temporal and spatial changes in pig manure load in agricultural lands in China

Crop-livestock and poultry farming cycle is an important way of solving agricultural non-point source pollution, promoting chemical fertilizers reduction and enhancing sustainable development of agriculture. Rational utilization of manure in agricultural lands is the basis of regional crop-livestock and poultry farming cycle. In order to control the pollution of breeding pigs through crop and pig farming cycle, we used the emission coefficient method to calculate the load intensity and carrying capacity of pig manure in agricultural lands in 31 provinces (municipalities) in China for the period 2007-2016. The spatial statistical model in ArcGIS was used to analyze temporal and spatial patterns of the evolution of pig manure load intensity in farmlands during the investigated decade. Then the multivariate linear regression model was used to explore the main driving factors of temporal and spatial differences in load intensity of pig manure in farmlands. The results showed that the load intensity of pig manure in China''s agricultural lands in 2007-2016 was low, which was 4.148 t·hm^-2 averagely with obvious inter-provincial variations. The load intensity generally increased first and decreased then. There were five evolution patterns of pig manure load intensity in farmlands in 31 provinces. They were continuous upward trend in Qinghai and Tibet; down-up-up trend in Xinjiang; continuous downward trend in 4 province of Ningxia, Sichuan, Guizhou and Hebei; up-up-down trend in 12 provinces including Shanghai; up-down-down trend in 6 provinces including Chongqing; and down-up-down trend in 6 provinces including Inner Mongolia. The load intensity of pig manure in farmland showed significant spatial autocorrelation on the whole, which initially decreased and then increased during the decade. The hotpot regions of load intensity of pig manure apparently shifted to the north and west from the east and south. The multivariate linear regression analyses showed that urban-rural income ratio, crop area per capita and proportion of sections with excellent water quality had negative effects, while profit rate in the last year, annual pork consumption per capita, population density, river network density had positive effects on pig manure load intensity in farmland. These factors affected load intensity mainly through market rules, supply-demand relationship, environmental carrying capacity, livestock and poultry farming regulations and government policies. Finally, policy recommendations were put forward based on the results, such as formulating regional plans and negative list policies based on provincial shift of load intensity hotspots and carrying capacity of pig manure in farmlands, establishing cycle-coupling industries of crop farming and livestock/poultry in a certain area.