沼液对狼尾草地土壤微生物群落的影响

Effects of Biogas Slurry Application on the Soil Microorganisms of P.americanum×P.purpureum Grassland

为探明沼液浇灌对土壤肥力及微生物的影响,揭示沼液提高土壤肥力的机制,本文采用氯仿熏蒸法、荧光定量PCR(fluorescence quantitative PCR)和PCR-DGGE法研究不同梯度沼液浇灌量(折纯N量200,150,100,50kg N·hm-2)对狼尾草(P.americanum×P.purpureum)地土壤微生物的影响。结果表明,与对照相比,沼液浇灌能显著提高土壤微生物生物量N和C,且沼液浇灌量与微生物量N和C的增量显著相关。沼液浇灌还能显著增加细菌16SrDNA基因和真菌SSU rDNA基因丰度,其中200kg N·hm-2处理含16SrDNA基因和SSU rDNA基因的微生物数量最多,沼液浇灌量与土壤中含16SrDNA基因和SSU rDNA基因的微生物数量呈显著正相关,但显著降低固氮菌nifH的基因丰度。沼液浇灌人工草地对包括细菌、真菌和固氮菌在内的土壤微生物群落多样性无显著影响,可促进含16SrDNA基因和SSU rDNA基因的微生物繁殖,但在一定程度上会抑制含nifH基因的微生物的繁殖,改变土壤含16SrDNA基因、SSU rDNA基因和nifH基因的微生物数量。

In order to reveal the effects of biogas slurry application on improving soil fertility,the change of soil microorganisms under different amounts of biogas slurry（equal to 200,150,100 and 50kg N·ha^-2pure N）application on Pennisetum.americanum×Pennisetum.purpureumgrassland was studied by chloroform fumigation,fluorescence quantitative PCR and PCR-DGGE methods based on field experiment.The results showed that soil microbial biomass C and N of 4treatments significantly increased by biogas slurry application compared to control,and there was a significant correlation between the slurry application amount and the increment of soil microbial biomass C and N.Biogas slurry significantly increased the abundance of 16 SrDNA and SSU rDNA gene which was significantly related with the application amount of biogas slurry,and the quantities of 16SrDNA-containing bacterial and SSU rDNA-containing fungi were the maximum in the treatment of containing 200 kg N·ha^-2 biogas slurry,while the abundance of nifHcontaining gene significantly decreased.As a result,it could conclude that the application of biogas slurry has no significant effect on the community diversity of soil bacteria,fungi and nitrogen-fixing bacteria,but promotes the growth of microorganisms containing 16 SrDNA gene and SSU rDNA genes,inhibits bacteri-al growth containing nifH gene,and changes the number of microorganisms.