농경지에서 낮은 곳으로의 질소 가스 문제 해결

For agricultural NO emission, Wang, et al.39 estimated that the annual NO emission from soils was about 657 Gg-N, and approximately 73.7% and 22.0% of the total NO emissions in July 1999 originated from arable lands and grasslands, respectively. Another study by Lu, et al.40 estimated that the annual soil NOx emissions above canopy in 2008–2017 were 0.77 ± 0.04 Tg-N. For comparison, the total anthropogenic NOx emissions, including power plant, industry, transportation, and residential processes, over China in 2010 were estimated to be 27.3 Tg per year (derived from MEIC v1.2)41. For the agricultural N2O source, Gao, et al.2O emissions from Chinese croplands from 1980 to 2007 using localized emission factors. Biogeosciences 8, 3011–3024 (2011)." href="/articles/s41612-022-00265-3#ref-CR42" id="ref-link-section-d498526e1425"42 estimated the direct N2O emission from paddy soils in China in 2007 was approximately 35.7 Gg N2O-N per year, with an annual increase rate of 0.4% since 1980. During 2007–2016, the soil N2O emission in China was about 1.4 ± 0.8 Tg-N per year28./p> 10 cmol kg−1): NH3 volatilization ranges from 0.20‒1.00 cmol kg−1./p>1.00 cmol kg−1./p>

Both balanced fertilization and improved NUE are always the most effective strategies to reduce nitrogenous oxide emissions from farmlands. Aside from the above front-end approaches, the NO emission can be controlled by a number of back-end practices, such as (i) adjustments of soil moisture, (ii) the application depth of N fertilizer, (iii) the use of organic fertilizers, and (iv) the use of controlled-release fertilizers. The increase in the application depth of fertilizers could effectively reduce the NO emission because of potential NO sorption by soils. Nutr. Cycl. Agroecosyst. 63, 231–238 (2002)." href="/articles/s41612-022-00265-3#ref-CR124" id="ref-link-section-d498526e4919">124. For urea, deep placement (e.g., 0.12 m deep in the case of Andisols125) would be highly effective in reducing NO emissions; however, relatively less effective on N2O emissions. For the organic farming system, a number of studies have proven that organic fertilizers could greatly reduce nitrogenous oxide emissions from various crops, such as managed vegetable systems115. Organic fertilizers could result in a low NO emission intensity as the denitrification could be enhanced by the increase of soil organic carbon and pH115. Cheng, et al.. Nutr. Cycl. Agroecosyst. 63, 231–238 (2002)." href="/articles/s41612-022-00265-3#ref-CR124" id="ref-link-section-d498526e4938"124 also noticed that banded controlled-release urea can significantly reduce the NO emission by 78.8‒82.6%, in comparison with the conventional urea. However, the effect of organic farming on N2O emission reduction is still a topic of discussion. For instance, a recent study126 indicated that the use of livestock manures could reduce both NO (by 46.5–59.8%) and N2O (by 41.4–49.6%) emissions in comparison to urea fertilizer. Abbasi, et al.127 also found that the use of organic manure in corn growing seasons would produce less N2O emissions, compared to innorganic ammonium nitrate; however, it resulted in a higher N2O emission in unfertilized soybean seasons./p>

For reducing the N2O emission, several practical methods have been developed and deployed, such as (i) keeping soils in aerobic conditions by optimum irrigation-drainage management, and avoidance of soil compaction by animals or traffic2, (ii) using slow release fertilizers128, urease inhibitor129, or nitrification inhibitor130, (iii) incorporating (bio-)organic fertilizers131 and biochars132 in soil-plant systems, and (iv) sowing legume crops in the fallow period between crop cycles133. In particular, the green practice of using inhibitors has been greatly advocated by numerous studies. Subbarao and Searchinger134 propsed the concept of maintaining the status of fertilizers in soil systems as a "more ammonium solution" by applying biological nitrification inhibitors. Biological nitrification inhibitors typically work at least 10 cm underground in the rhizosphere; therefore, the NH3 emission from soils, on the other hand, would not increase135. Wang, et al.130 has critically reviewed the effect of biological nitrification inhibitors on the N2O emission. Nitrification inhibitors can be transported through the roots to the active sites for nitrification in the soils to increase NUE and yield, thereby reducing N2O emissions. For instance, the use of the urease and/or nitrification inhibitors can significantly reduce N2O emissions, e.g., by up to 65.4% in the case of NBPT and DCD129. Maaz, et al.107 also reported a wide range of N2O emission reduction by 8‒100% when introducing nitrification inhibitors or combined with urease inhibitors. Cheng, et al.. Nutr. Cycl. Agroecosyst. 63, 231–238 (2002)." href="/articles/s41612-022-00265-3#ref-CR124" id="ref-link-section-d498526e5025"124 also noticed that banded controlled-release urea can significantly reduce the N2O emission by 31.6‒40.5%, in comparison with the conventional urea./p>2O emissions from Chinese croplands from 1980 to 2007 using localized emission factors. Biogeosciences 8, 3011–3024 (2011)./p>

. Nutr. Cycl. Agroecosyst. 63, 231–238 (2002)./p>