Estimating regional N application rates for rice in China based on target yield, indigenous N supply, and N loss. (August 2020)

• Record Type: Journal Article
• Authors: Ding, Wencheng; Xu, Xinpeng; He, Ping; Zhang, Jiajia; Cui, Zhenling; Zhou, Wei
• Is Part Of: Environmental pollution. Volume 263(2020)Supplement Part B
• Publication Date: 2020-08
• Subjects: N loss -- Soil N depletion -- Straw return -- Slow-release N -- Manure cycling; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2020.114408
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Decision-making related to nitrogen (N) applications based solely on historic experience is still widespread in China, the country with the largest rice production and N fertilizer use. By connecting N application rates with target N uptake, indigenous N supply, and N loss estimates collected from 1078 on-farm experiments, we determined regional N application rates for five rice-based agroecosystems, including a quantification of the reduction potential of application rates when using low-loss N sources, such as organic N and slow-release N. Based on our results, the moderate regional N application rates were 165, 180, 160, 153, and 173 kg N ha −1 for single, middle-CE (Central and Eastern China), middle-SW (Southwestern China), early, and late rice, respectively; lower (99–148 kg N ha −1 ) and upper (195–217 kg N ha −1 ) limits of N application rates were developed for situations with sufficient and insufficient indigenous N supplies, respectively. The depletion of soil N mineralization was quantified as 46.8–67.3 kg ha −1, and straw return is determined to be a robust measure to maintain soil N balance. Substituting manure or slow-release N for conventional N fertilizer significantly decreased N losses via NH3 volatilization, leaching, runoff, and N2 O emissions. Overall, we observed 7.2–11.3 percent point reductions of N loss rate for low-loss N sources when compared to conventional N applications. On average, total N application rates could be theoretically reduced by 27 kg N ha −1 by using a slow-release N fertilizer, or by 30 kg N ha −1 when using manure due to their effectiveness at decreasing system N losses. Greater productivity, sustainable soil fertility, and a lower risk of N pollution would result from the ideal N application rate coupled with appropriate management practices. Widespread adoption of using low-loss N sources could become a key solution for future reduction in environmental N pollution and agricultural N inputs. Graphical abstract: Image 1 Highlights: The optimal N application rate ranged from 153 to 180 kg N ha −1 for different rice ecosystems on a regional scale. We demonstrated that returned straw provided enough N source to compensate the depletion of soil N pool in a rice season. Low-loss N sources decreased N loss rates by 7.2–11.3 percent points and thereby could reduce N input by 24–37 kg N ha −1 . Abstract : We determined regional N application rates of 99–217 kg N ha −1 for different rice ecosystems and reduction potentials of 24–37 kg N ha −1 using low-loss N sources.