Rao Demin, Meng Fangang, Yan Xiaoyan, Zhang Minghao, Yao Xingdong, Kim Kyung Seok, Zhao Jing, Qiu Qiang, Xie Futi, Zhang Wei
Soybean Research Institute, Shenyang Agricultural University, Shenyang, China.
Jilin Academy of Agricultural Sciences, Changchun, China.
Front Microbiol. 2021 Apr 7;12:638326. doi: 10.3389/fmicb.2021.638326. eCollection 2021.
Corn-soybean rotation and fertilization are common practices improving soil fertility and crop yield. Their effects on bacterial community have been extensively studied, yet, few comprehensive studies about the microbial activity, bacterial community and functional groups in a long-term continuous soybean cropping system after corn insertion and fertilization. The effects of corn insertions (Sm: no corn insertion, CS: 3 cycles of corn-soybean rotations and CCS: 2 cycles of corn-corn-soybean rotations) with two fertilization regimes (No fertilization and NPK) on bacterial community and microbial activity were investigated in a long-term field experiment. The bacterial communities among treatments were evaluated using high-throughput sequencing then bacterial functions were predicted based on the FaProTax database. Soil respiration and extracellular enzyme activities were used to assess soil microbial activity. Soil bacterial community structure was significantly altered by corn insertions ( < 0.01) and fertilization ( < 0.01), whereas bacterial functional structure was only affected by corn insertion ( < 0.01). The activities of four enzymes (invertase, β-glucosidase, β-xylosidase, and β-D-1,4-cellobiohydrolase) involved in soil C cycling were enhanced by NPK fertilizer, and were also enhanced by corn insertions except for the invertase and β-xylosidase under NPK fertilization. NPK fertilizer significantly improved soil microbial activity except for soil metabolic quotient (qCO) and the microbial quotient under corn insertions. Corn insertions also significantly improved soil microbial activity except for the ratio of soil induced respiration (SIR) to basal respiration (BR) under fertilization and the qCO was decreased by corn insertions. These activity parameters were highly correlated with the soil functional capability of aromatic compound degradation, which was the main predictors of bacterial functional structure. In general, the combination of soil microbial activity, bacterial community and corresponding functional analysis provided comprehensive insights into compositional and functional adaptations to corn insertions and fertilization.
玉米-大豆轮作和施肥是提高土壤肥力和作物产量的常见做法。它们对细菌群落的影响已得到广泛研究，然而，关于玉米插入和施肥后长期连作大豆系统中微生物活性、细菌群落和功能群的综合研究较少。在一项长期田间试验中，研究了两种施肥方式（不施肥和氮磷钾施肥）下玉米插入（Sm：不插入玉米，CS：3个周期的玉米-大豆轮作，CCS：2个周期的玉米-玉米-大豆轮作）对细菌群落和微生物活性的影响。使用高通量测序评估各处理间的细菌群落，然后基于FaProTax数据库预测细菌功能。利用土壤呼吸和胞外酶活性评估土壤微生物活性。玉米插入（P<0.01）和施肥（P<0.01）显著改变了土壤细菌群落结构，而细菌功能结构仅受玉米插入影响（P<0.01）。参与土壤碳循环的四种酶（转化酶、β-葡萄糖苷酶、β-木糖苷酶和β-D-1,4-纤维二糖水解酶）的活性在氮磷钾施肥下增强，除了在氮磷钾施肥下转化酶和β-木糖苷酶外，玉米插入也增强了这些酶的活性。除了土壤代谢商（qCO₂）和玉米插入下的微生物商外，氮磷钾施肥显著提高了土壤微生物活性。玉米插入也显著提高了土壤微生物活性，除了施肥下土壤诱导呼吸（SIR）与基础呼吸（BR）的比值，且玉米插入降低了qCO₂。这些活性参数与芳香族化合物降解的土壤功能能力高度相关，这是细菌功能结构的主要预测指标。总体而言，土壤微生物活性、细菌群落和相应功能分析的结合为玉米插入和施肥的组成和功能适应性提供了全面的见解。
