Driving forces and future trends on total nitrogen loss of planting in China.

Nitrogen production is one of the major aspects of global change over the past century. Nowhere is this change more dramatic than in China. Understanding the variations and driving forces of nitrogen loss from planting is critical to the sustainable development of Chinese agriculture. Here we found total nitrogen (TN) loss of China showed an overall downward trend from 2007 to 2016, as a result of abatement strategies for China on "Soil Testing and Formula Fertilization" and "Reducing Fertilizer Application while Increase the Efficiency", based on the data of National Agricultural Pollution Survey. The results of structural equation model showed that the path coefficient of anthropogenic drivers and natural conditions on TN loss were 0.934 and -0.137 respectively, suggesting that anthropogenic drivers had greater effects on TN loss than natural conditions. In terms of anthropogenic drivers, fertilizer usage and consumption of chemical pesticides were the two major factors affecting TN loss with path coefficients of 0.958 and 0.946, respectively, which was mainly related to their over-application. For natural conditions, relative humidity, water supply situation, and annual precipitation were found to be the dominant factors affecting TN loss, revealing that moist soils increased TN loss by enhancing ammonia volatilization, denitrification and nitrogen leaching. Forecasts for 2050, under two scenarios especially for the high TN loss scenario, the indication sifts that China will face a high risk of increasing TN loss from planting, suggesting that China's abatement strategies cannot be slackened. Here, the current status and future trends of China's nitrogen loss provide direction and pertinence to Chinese abatement strategies for nitrogen, effectively preventing and controlling agricultural non-point source pollution.