生物质炭对稻田氮素淋失和氧化亚氮排放的影响

Impact of Biochar on Nitrogen Leaching and Nitrous Oxide Emission in Paddy Soils

为降低农田面源污染和温室气体排放,通过田间试验研究了优化施氮情况下,添加不同剂量生物质炭(0、4.5、9、13.5 t/hm^2)对宁夏引黄灌区稻田土壤氮素淋失和土壤N_2O排放的影响。结果表明,添加生物质炭显著降低了100 cm土层处的硝态氮和铵态氮淋失量,降低比例分别为18.23%~26.02%和28.86%~52.05%。与C0处理相比,C1处理(4.5 t/hm^2)对土壤N_2O累计排放量影响不显著,但C2处理(9 t/hm^2)和C3处理(13.5 t/hm^2)土壤N_2O累计排放量显著降低了25.13%和28.88%。添加生物质炭可增加水稻产量和吸氮量,降低土壤硝态氮和铵态氮量以及土壤体积质量,是引起土壤氮素淋失降低和土壤N_2O排放减少的重要原因之一。综合考虑生物质炭对土壤氮素淋失和土壤N_2O排放的影响以及生产成本,宁夏引黄灌区的生物质炭推荐添加量为9 t/hm^2。

Nitrogen leaching and emission as greenhouse gases are an important environmental issue in agricultur- al production. This paper investigated how optimizing fertilization and amending soil with biochar could reduce nitrate leaching and N20 emission from a paddy field in Yellow River Irrigation Region inNinxia. Biochar was ap- plied to soil at three rates （4.5, 9 and 13.5 t/hm2 per years）, and no biochar amendment was taken as the control. The results showed that biochar amendment reduced leaching of nitrate and ammonium by 18.23%~26.03% and 28.86%~52.05% respectively. The C1 treatment （4.5 t/hm2） did not significantly reduce N20 emissions, but C2 （9 t/hm2） and C3 （13.5 t/hm2） did and reduced accumulative N20 emission by 25.13% and 28.88%, respectively. Amending soil with biochar increased the uptake of nitrogen by plant roots, thereby reducing nitrate and ammoni- um in soil as well as soil density, which is the main reason behind the reduction in nitrogen leaching and emis- sions from soil. Our results revealed that amending the paddy soil with biochar at 9 t/hm2 can effectively increase nitrogen uptake and reducenitrogen loss as a result.