Decoupling Agricultural Nonpoint Source Pollution from Crop Production: A Case Study of Heilongjiang Land Reclamation Area, China

Modern agriculture often leads to nonpoint source pollution. From the perspective of a decoupling analysis, this research evaluates the relationship between crop production and agricultural nonpoint source pollution (via fertilizer application), using the Heilongjiang land reclamation area as a case study. As it is the largest commodity grain base and green food base in China, more than 80% of water pollution in this area comes from fertilizer application. This study adopts an export coefficient model to hindcast nitrogen loss delivered to surface water via fertilizer application and conduct a further analysis of decoupling agricultural nonpoint source pollution from crop production. The results indicated that weak decoupling frequently occurred. However, this tendency was not steady in the period 2001–2012, and weak decoupling was typical in each branch based on the average value. Regarding the example of decoupling agricultural nonpoint source pollution from rice production, weak decoupling occurred more often, but this tendency was not steady over time. In addition, expansive coupling occurred in 2006, 2010 and 2012, and there were no definite signs of it improving. All branches, except for the Suihua branch, reached the degree of weak decoupling. A basic fact is that a decoupling tendency and environmental deterioration coexist in both the past and present. The decoupling analysis will contribute to localized strategies for sustainable agricultural development.