Promotion of Maize Straw Degradation Rate by Altering Microbial Community Structure through the Addition of Soybean Straw

The carbon-nitrogen ratio (C/N ratio) of straw significantly influences its mineralization and nutrient release when returned to the soil. This study utilized indoor culture and outdoor pot experiments to investigate the impact of varying straw ratios on straw mineralization, soil property dynamics, soil microbial communities, soil enzyme activities, and maize growth. Design of treatments included: (1) maize straw return (M), (2) soybean straw return (S), (3) 1:1 ratio of maize straw and soybean straw return (MS), (4) 2:1 ratio of maize straw to soybean straw return (2MS), (5) maize straw return combined with nitrogen fertilizer (MF) and (6) no straw return (NS). Compared with M treatment, MS and MF treatment enhanced the straw mineralization rate and nutrient release, thus increasing the biomass of succeeding maize. The MS treatment increased the relative abundance of Chloroflexi, Acidobacteriota, and Proteobacteria by 15.54%, 5.36%, and 14.29%, respectively, compared to the M treatment. Straw return treatments significantly decreased the prevalence of the pathogenic fungus Fusarium compared to the NS approach. Correlation analyses indicated a positive association between soil chemical properties and the presence of Proteobacteria, Firmicutes, Bdellovibrionota, and Nitrospirota. Conversely, these factors showed a negative correlation with Actinobacteriota, Gemmatimonadota, Funneliformis, Trichoderma, and Fusarium. These changes in microbial communities are beneficial for straw degradation and nutrient release. In summary, the combined addition of soybean straw and maize straw in a 1:1 ratio optimizes the microbial community, enhances soil nutrient cycling, improves soil fertility, and positively affects corn biomass and nutrient uptake.

秸秆的碳氮比（carbon-nitrogen ratio, C/N ratio）在还田后对其矿化过程与养分释放具有显著调控作用。本研究采用室内培养试验与室外盆栽试验，探究不同秸秆配比还田对秸秆矿化、土壤属性动态变化、土壤微生物群落结构、土壤酶活性以及玉米生长的影响。试验处理设计如下：(1) 玉米秸秆还田（M），(2) 大豆秸秆还田（S），(3) 玉米秸秆与大豆秸秆按1:1质量比还田（MS），(4) 玉米秸秆与大豆秸秆按2:1质量比还田（2MS），(5) 玉米秸秆还田配施氮肥（MF），(6) 无秸秆还田（NS）。相较于M处理，MS与MF处理可提升秸秆矿化速率与养分释放量，进而增加后茬玉米的生物量。与M处理相比，MS处理下绿弯菌门（Chloroflexi）、酸杆菌门（Acidobacteriota）与变形菌门（Proteobacteria）的相对丰度分别提升15.54%、5.36%与14.29%。相较于NS处理，各秸秆还田处理均显著降低了病原真菌镰刀菌属（Fusarium）的相对占比。相关性分析结果表明，土壤化学性质与变形菌门、厚壁菌门（Firmicutes）、蛭弧菌门（Bdellovibrionota）以及硝化螺旋菌门（Nitrospirota）的相对丰度呈正相关；反之，与放线菌门（Actinobacteriota）、芽单胞菌门（Gemmatimonadota）、漏斗孢霉属（Funneliformis）、木霉菌属（Trichoderma）以及镰刀菌属（Fusarium）呈负相关。上述微生物群落的变化有利于秸秆降解与养分释放。综上，按1:1配比混合还田的大豆秸秆与玉米秸秆可优化土壤微生物群落结构，强化土壤养分循环，提升土壤肥力，并对玉米生物量与养分吸收产生积极影响。