玉米秸秆还田量对砂姜黑土酶活性、微生物生物量及细菌群落的影响

Effects of maize straw returning amount on soil enzyme activity, microbial biomass, and bacterial community in lime concretion black soil

为探讨砂姜黑土区秸秆还田量对土壤生物学特性的影响,以小麦-玉米轮作为研究对象,通过2年的大田试验,分析了0、1/3、2/3和100%玉米秸秆还田量处理(CK、S3、S6和S9)土壤酶活性、微生物生物量及细菌群落变化的特征。结果表明:与CK处理相比,S6和S9处理显著提高了土壤有机碳(12.9%和14.4%)、碱解氮(21.4%和25.6%)、有效磷(17.9%和20.5%)和速效钾含量(25.9%和29.8%)。秸秆还田处理下土壤脲酶、纤维素酶活性和微生物生物量碳含量显著增加,增幅分别为22.5%~44.6%、23.9%~52.1%和16.6%~46.7%,且S6和S9处理较CK处理显著提高了木聚糖酶活性(32.7%和21.2%)和微生物生物量氮含量(53.5%和54.4%)。与CK处理相比,S6和S9处理细菌群落多样性显著增加,而S3处理则无显著变化。放线菌门、变形菌门、酸杆菌门、绿弯菌门和厚壁菌门为优势细菌门,其中酸杆菌门相对丰度在秸秆还田处理下显著降低了2.6~4.7个百分点,而变形菌门相对丰度在S6和S9处理下显著增加了3.8、4.9个百分点;热酸菌属、布氏杆菌属和芽孢杆菌属为优势细菌属,其中芽孢杆菌属相对丰度在秸秆还田处理下显著增加了1.2~2.9个百分点,而布氏杆菌属相对丰度在S6和S9处理下显著降低了1.4、1.8个百分点。冗余分析结果表明,有机碳、微生物生物量碳和脲酶是影响细菌群落组成的关键因子。综上,在砂姜黑土区,2/3(6000 kg·hm^(-2))和100%玉米秸秆还田量(9000 kg·hm^(-2))均能够改善土壤养分状况及生物学特性,可根据当地情况选择适宜用量。

To investigate the effect of the amount of straw returning on the biological characteristics of lime concretion black soil,we used the wheat-corn rotation system as a research object and analyzed the changes in the enzyme activity,microbial biomass,and bacterial community of the soil under the conditions of 0(CK),1/3(S3),2/3(S6),and 100%(S9)returning amounts of maize straw.The results showed that the S6 and S9 treatments significantly increased the contents of organic carbon(by 12.9%and 14.4%,respectively),alkali hydrolyzable nitrogen(by 21.4%and 25.6%,respectively),available phosphorus(by 17.9%and 20.5%,respectively),and available potassium(by 25.9%and 29.8%,respectively)in the soils.All the straw returning treatments significantly increased the activities of urease and cellulase and the content of microbial biomass carbon by 22.5%~44.6%,23.9%~52.1%and 16.6%~46.7%,respectively.Moreover,the S6 and S9 treatments significantly increased the xylanase activity(by 32.7%and 21.2%,respectively)and the content of microbial biomass nitrogen(by 53.5%and 54.4%,respectively).Compared with the CK treatment,the S6 and S9 treatments significantly increased the bacterial community diversity,whereas the S3 treatment did not.Actinobacteria,Proteobacteria,Acidobacteria,Chloroflexi,and Firmicutes were the dominant bacterial phyla.The relative abundance of Acidobacteria significantly decreased by 2.6~4.7 percentage points under the straw returning treatments,whereas the relative abundance of Proteobacteria significantly increased 3.8 and 4.9 percentage points under the S6 and S9 treatments,respectively.Acidothermus,Bryobacter,and Bacillus were the dominant bacterial genera.The relative abundance of Bacillus significantly increased by 1.2~2.9 percentage points under straw returning treatments,whereas the relative abundance of Bryobacter significantly decreased by 1.4 and 1.8 percentage points under the S6 and S9 treatments,respectively.The RDA result showed that organic carbon,microbial biomass carbon,and urease were the key factors affecting the bacterial community.In conclusion,2/3(6000 kg·hm^(-2)) and 100%(9000 kg·hm^(-2)) returning amounts of maize straw in lime concretion black soil can improve soil nutrients and biological characteristics of soil.The returning amounts of maize straw can be selected according to local conditions.