Mitigating nitrous oxide emissions from a maize-cropping black soil in northeast China by a combination of reducing chemical N fertilizer application and applying manure in autumn |
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Authors: | Yanling Guo Liangguo Luo Guanxiong Chen Yongping Kou |
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Affiliation: | 1. Institute of Applied Ecology , Chinese Academy of Sciences , Shenyang , 110016 , China;2. Graduate University of Chinese Academy of Sciences , Beijing , 100039 , China;3. Key Laboratory for Agro-Environment &4. Climate Change of Ministry of Agriculture , Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences , Beijing , 100081 , China;5. Institute of Applied Ecology , Chinese Academy of Sciences , Shenyang , 110016 , China |
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Abstract: | Abstract Nitrous oxide (N2O) emissions from agricultural soils, mainly caused by chemical nitrogen (N) fertilizer inputs, are major sources of N2O in Chinese terrestrial ecosystems. Thus, attempts to reduce N2O emissions from agricultural soils by optimizing N applications are receiving increasing attention. Further, organic fertilizers are being increasingly used in China to improve crop production/quality and prevent or reduce soil degradation. However, organic and chemical fertilizers are often both applied in spring in northeast China, which promotes N2O emissions and may be sub-optimal. Therefore, we hypothesized that reducing applications of chemical fertilizer N and applying manure in autumn could be an effective strategy for mitigating N2O emissions from cropped soils in the region. To test this hypothesis, we established a field trial to investigate the effects of different combinations of chemical N fertilizer applications and animal manure in autumn on both N2O emissions and maize (Zea mays L.) grain yields in northeast China. The treatments, expressed as NxMy (where Nx and My denote the total amounts of chemical fertilizer nitrogen (N) and manure (M) applied in kg N ha?1 and m3 M ha?1, respectively), were N0M0, N230M0, N270M12, N230M15, N320M18 in 2010 and N0M0, N230M0, N200M12, N200M15, N280M18 in 2011. Measurements of the resulting N2O emissions showed that pulse fluxes occurred after each chemical N fertilizer application, but not after manure inputs in autumn or during soil-thawing periods in the following spring. Emission factors for the chemical fertilizer N were on average 1.07% (1.00?1.10%) and 1.14% (0.49?1.83%) in 2010 and 2011, respectively. Furthermore, by comparing the nine pairs of fertilization treatments, the relative increase in cumulative nitrous oxide-nitrogen (N2O-N) emissions was found to be proportional to the relative increase in urea application, but independent of the amount of autumn-applied manure. These findings imply that N2O emissions from fertilized agricultural soils in northeast China could be mitigated by supplying manure in the autumn and reducing the total amount of chemical N fertilizer applied in the following year. Although no significant difference in maize grain yield was found among the fertilization treatments, the grain yield-scaled N2O emissions for the treatments with a lower chemical N application (e.g., N230M15 and N200M15 treatments) were significantly lower than those with a higher chemical N application (e.g., N320M18 and N280M18 treatments). Meanwhile, under the condition of the same application amount of chemical fertilizer N, the grain yield-scaled N2O emission decreased with the increase of manure application rate. Thus, the results support the hypothesis that combining reductions in chemical N fertilizer and applying manure in autumn could be an effective strategy for mitigating N2O emissions from N-fertilized soils in northeast China. |
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Keywords: | maize cropping soil N2O chemical N fertilizer manure grain yield |
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