秸秆颗粒还田对黑土土壤酶活性及细菌群落的影响

为探讨不同玉米秸秆颗粒还田量对黑土生物学特性及细菌群落的影响,在内蒙古兴安盟扎赉特旗农业科技示范园试验地设置秸秆0%还田,还田量0kg/hm^2(CK)、秸秆60%还田,还田量4500kg/hm^2(JG1)、秸秆70%还田,5250kg/hm^2(JG2)、秸秆80%还田,6000kg/hm^2(JG3)、秸秆90%还田,6750kg/hm^2(JG4)和秸秆100%还田,7500kg/hm^2(JG5)6个处理,通过连续2年大田试验,研究土壤蔗糖酶、脲酶、过氧化氢酶、碱性磷酸酶活性、微生物生物量碳氮以及细菌群落的变化。结果表明:秸秆还田能够增加土壤蔗糖酶(3.29%—32.12%),脲酶(5.32%—52.66%),过氧化氢酶(0.60%—27.11%),碱性磷酸酶的活性(10.89%—64.20%),土壤微生物生物量碳(1.32%—7.07%)、氮(16.35%—80.46%)含量;秸秆施入土壤也提高了黑土变形菌门和厚壁菌门相对丰度,提高了土壤固氮、分解养分及抵御病害能力,并降低了放线菌门相对丰度,降低了土壤病害发生概率,还出现了具有固氮、吸磷、改良土壤特性的新细菌,可见玉米秸秆还田具有重要的生态学意义,可在一定程度上增加细菌数量和种类多样性,进而使土壤系统向稳定健康的方向发展。综合研究结果在本试验条件下,以6750kg/hm^2为较适宜的玉米秸秆颗粒还田量。

Effects of returning granulated corn stover on soil enzyme activities and bacterial community in black soil

To investigate the effects of returning granulated corn stover on biological properties and bacterial communities of black soils, a 2-year field experiment was conducted in Jalaid Banner, Inner Mongolia in 2016 and 2017. Amount of corn stover incorporated in soil were 0 kg/hm² (CK, 0%), 4500 kg/hm² (JG1), 5250 kg/hm² (JG2), 6000 kg/hm² (JG3), 6750 kg/hm² (JG4), and 7500 kg/hm² (JG5, 100%). The changes in soil sucrase, urease, catalase, alkaline phosphatase enzyme, microbial biomass carbon, and nitrogen, as well as the bacterial community were studied. Results showed that, returning corn stover to the field increased the activity of soil sucrase (by 3.29%-32.12%), urease (by 5.32%-52.66%), catalase (by 0.60%-27.11%), alkaline phosphatase enzyme (by 10.89%-64.20%), microbial biomass carbon (by 1.32%-7.07%), and nitrogen (by 16.35%-80.46%). The returning of corn stover increased the relative abundance of Proteobacteria and Firmicutes in black soil, which can enhance the ability of soil nitrogen fixation and disease resistance and reduce the probability of soil disease through decreased relative abundance of Actinomycetes. New bacteria with the capability for nitrogen fixation, phosphorus uptake, and soil improvements also increased. In conclusion, returning of corn stover to soil has important ecological impacts on the agroecosystem, which can enhance the abundance and generic diversity of soil nematodes, creating a stable and healthy soil ecosystem. According to our study, 6750 kg/hm² or 90% returning rate is suitable for granulated stover returning.