沼液对种植狼尾草的山地红壤可溶性有机氮和土壤微生物特征的影响

Effect of Biogas Slurry Application on Soluble Organic Nitrogen and Microbial Characteristics of Hilly Red Soil Under Pennisetum(P.americanum and P.purpureum)Grassland

通过沼液浇灌人工草地定位试验，研究浇灌不同浓度梯度沼液下土壤可溶性无机氮、可溶性有机氮、可溶性有机碳、微生物量碳（SMBC）、微生物量氮（SMBN）、细菌16SrDNA基因、真菌SSUrDNA基因、固氮菌nifH基因丰度及细菌、真菌、固氮菌群落多样性的变化。结果表明，人工草地土壤可溶性氮以有机氮为主，占可溶性总氮含量的77．87％～88．88％，沼液浇灌使人工草地土壤可溶性有机氮含量呈增加趋势，但这种变化未达到显著水平；沼液浇灌能显著提高SMBN、SMBC和MQ，还能显著增加细菌16SrDNA基因和真菌SSUrDNA基因的丰度，降低固氮菌nifH基因的丰度，但对细菌、真菌和固氮菌多样性无显著影响，表明沼液短期浇灌可促进土壤微生物的繁殖，但对微生物群落构成无显著影响；沼液与SMBC、细菌16SrDNA基因丰度、真菌sSUrDNA基因丰度之间显著正相关，sON与土壤真菌SSUrDNA基因丰度显著正相关，与固氮菌nifH基因丰度显著负相关（p〈0．05）。

Based on a field experiment, we studied soil soluble inorganic nitrogen（ISON）, soluble organic nitrogen（SON） and carbon（SOC）, soil microbial biomass carbon（SMBC） and nitrogen（SMBN）, bacterial 16S rDNA gene abundance, fungi SSU rDNA gene abundance, azotobacter nifH gene abundance and the diversities of soil bacterial, fungal and azotobacter communities of artificial Pennisetum（P. americanum and P. purpureum） grassland with different concentration gradient of biogas slurry. The results showed that in this study, SON was the main component of soil total soluble nitrogen （TSN） in Pennisetum grassland, accounting for 77.87%-88.88% of TSN. Meanwhile, SON content was increased by application of biogas slurry, but no significant difference was observed among different treatments. Biogas slurry significantly increased SMBN, SMBC and microbial quotient（MQ）, and improved 16S rDNA gene abundance and fungi SSU rDNA gene abundance, while decreased azotobacter nifH gene abundance and did not significantly affect the diversities of soil bacterial, fungal and azotobacter communities. The results indicated that short-term application of biogas structure content slurry could promote the increase of soil microorganism abundance, but had no significant effect on the of soil microbial community. The concentration of biogas slurry was positively correlated with SMBC bacterial 16S rDNA gene abundance and fungi SSU rDNA gene abundance. Meanwhile, SON was positively correlated with fungi SSU rDNA gene abundance, while negatively correlated with azotobacter nifH gene abundance（p〈0.05）.