Increased ammonia emissions from synthetic fertilizers and land degradation associated with reduction in arable land area in China

Abstract For a long time, there has been an excessive use of synthetic fertilizers applied to the decreasing area of arable land to help meet the increasing food demand, which causes NH 3 volatilization and land degradation. In this study, we conducted a nationwide inventory of NH 3 emissions from synthetic nitrogen fertilizers in China from 1991 to 2013. We estimated that NH 3 emissions increased from 3.20 to 5.21 Tg NH 3 yr −1 . Because of the different agricultural practices, fertilizer use schedules, and ambient temperature, monthly NH 3 emissions have varied greatly. NH 3 emissions during the spring and summer accounted for approximately 83% of the national total in 1991, 1998, 2005, and 2013. Similarly, the spatial distribution of NH 3 emissions exhibited large heterogeneity in 1991, 1998, 2005, and 2013. High emissions occurred in the eastern and central provinces and eastern Sichuan. Based on NH 3 emissions in Chinese counties for 1991–1998, 1999–2005, and 2006–2013, the Pearson correlation coefficient was applied to compute the changing trends in NH 3 emissions and fertilization rates. The results showed that the NH 3 emissions from the major grain‐producing regions increased, whereas those from the eastern provinces, which experienced rapid economic development, decreased. In addition, fertilizer amount, arable land area, grain yield, and primary industry have been shown to be largely correlated to NH 3 emissions based on principal component analysis. Therefore, the results of this study have significant implications for improving the efficient use of fertilizers and preventing soil and/or land degradation.