减氮配施生物炭对水稻生产力及土壤细菌群落组成的影响

Effects of nitrogen reduction combined with rice straw biochar on rice yield traits and soil bacterial community structure and function

为研究氮肥减量及配施生物炭对稻田作物生产力和土壤微生物区系及功能代谢的影响,通过田间定位试验,设置不施氮(CK)、常规施氮(N100)、减氮20%(N80)、减氮20%配施生物炭(N80BC)、减氮40%(N60)、减氮40%配施生物炭(N60BC)6个处理。结果表明:减氮配施生物炭处理不会降低水稻作物的产量,但可显著提高土壤pH和有机碳(TOC)含量。土壤微生物测序结果表明,不同处理对土壤细菌α多样性指数没有显著影响。变形菌(Proteobacteria)、绿弯菌(Chloroflexi)、酸杆菌(Acidobacteria)、放线菌(Actinobacteria)、芽单胞菌(Gemmatimonadetes)是水稻土中优势微生物类群(门水平)。N60BC处理的变形菌、芽单胞菌、放线菌的相对丰度分别比N100处理高36.8%、40.7%和11.3%;在属水平上,N60BC处理的鞘脂单胞菌属(Sphingomonas)、马赛菌属(Massilia)、芽单胞菌属(Gemmatimonas)的相对丰度分别比N100处理高68.6%、54.0%和49.2%。KEGG分析结果表明,与N100处理相比,N60BC处理显著增加土壤微生物的氨基酸代谢、碳水化合物代谢、脂类代谢和能量代谢功能。土壤总氮(TN)、TOC、pH对细菌群落的贡献率分别为19.4%、7.4%、6.8%。Pearson分析结果显示,土壤pH与酸杆菌的丰度呈显著正相关,土壤TN与变形菌、芽单胞菌的丰度呈显著正相关,而与绿弯菌、疣微菌(Verrucomicrobia)的丰度呈显著负相关(P<0.05)。研究表明,适量减少氮肥,同时配施生物炭可以改善土壤细菌的群落结构和功能,促进水稻的生长,是一种稻田减肥稳产的管理措施。

The effects of chemical nitrogen reduction and combined application of rice straw biochar on crop productivity and soil microbial community was investigated in a rice paddy system.A field positioning experiment was designed with six treatments:no nitrogen(CK),conventional nitrogen(N100),20%nitrogen reduction(N80),20%nitrogen reduction combined with biochar(N80BC),40%nitrogen reduction(N60),and 40%nitrogen reduction combined with biochar(N60BC).Nitrogen reduction combined with biochar did not reduce rice yield and significantly increased soil pH and organic carbon(TOC)content.The results of soil microbial sequencing showed that none of the treatments had no significant effect onαdiversity index of soil bacteria community.In general,Proteobacteria,Chloroflexi,Acidobacteria,Actinobacteria,and Gemmatimonadetes were the dominant bacterial phyla in paddy soil.Proteobacteria,Gemmatimonadetes,and Actinobacteria increased by 36.8%,40.7%and 11.3%in N60BC treatment compared with N100 treatment.At the genus level,Sphingomonas,Massilia,and Gemmatimonas increased by 68.6%,54.0%,and 49.2%,respectively,in N60BC treatment compared with N100 treatment.Based on the results of KEGG analysis,we determined that N60BC treatment significantly increased the amino acid metabolism,carbohydrate metabolism,lipid metabolism,and energy metabolism of soil microorganisms in comparison with N100.The contribution rates of soil total nitrogen(TN),TOC,and pH to bacterial community were 19.4%,7.4%,and 6.8%,respectively.Pearson analysis showed that soil pH was positively correlated with the relative abundance of Acidobacteria,TN was positively correlated with Proteobacteria and Gemmatimonadetes,and TN was negatively correlated with Chloroflexi and Verrucomicrobia(P<0.05).In conclusion,appropriate nitrogen fertilizer reduction combined with biochar can improve the structure and function of the soil bacteria community and promote the growth of rice;therefore,this combination is a viable management measure for chemical reduction and production stability in paddy fields.