College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China.
Sci Total Environ. 2020 May 1;715:136983. doi: 10.1016/j.scitotenv.2020.136983. Epub 2020 Jan 27.
Microbial activities are the dynamic core in the soil nutrient cycle. To improve the knowledges about the responses of soil microbial community structure and potential function to long-term cover crops practice. The co-occurrence patterns of soil microbial community structure and functional genes were evaluated using 16SrRNA, ITS and metagenomic technique in 13 years cover crops of orchard grass (OG, Dactylis glomerata L.) with high C/N and white clover (WC, Trifolium repens L.) with low C/N. Conventional tillage (CT) was control. The experiment was implemented in an apple orchard located on the Loess Plateau, China, from 2006 to 2018. We also measured soil physicochemical properties and enzyme activities related to carbon and nitrogen cycling. The conclusions showed that the dominant bacterial phyla were Actinobacteria 27.68% in OG treatment and Proteobacteria 25.89% in WC treatment. Organic matter inputs stimulated growth of the phyla of Actinobacteria, Firmicutes, Chloroflexi, Ascomycota and genera of Bacillus, Blastococcus, Streptomyces and Penicillium. Interestingly, the OG and WC treatments promoted the fungal and bacterial alpha-diversity compared to CT treatment, respectively. In addition, compared to CT treatment, OG treatment was beneficial to the increase of C-cycle enzyme activity, while WC treatment tended to increase the N-cycle enzyme activity. Notably, compared to CT treatment, they both enriched carbon fixation and cycle pathways genes, while WC treatment increased the nitrogen metabolism pathway genes. Moreover, OG treatment was more conducive to the enrichment of carbohydrate enzymes genes involved in the hydrolysis of cellulose and hemicellulose compared to WC treatment. Overall, different quality of plant residues stimulated the specific expressions of soil microbial community structure and function. Long-term planted white clover was effective strategy to improve soil quality.
微生物活性是土壤养分循环的动态核心。为了提高对长期覆盖作物实践中土壤微生物群落结构和潜在功能响应的认识，本研究采用 16SrRNA、ITS 和宏基因组技术，评估了果园草（OG，Dactylis glomerata L.）和白三叶草（WC，Trifolium repens L.）13 年覆盖作物中土壤微生物群落结构和功能基因的共生模式。其中，常规耕作（CT）为对照。该实验于 2006 年至 2018 年在中国黄土高原的一个苹果园中进行。我们还测量了与碳氮循环相关的土壤理化性质和酶活性。研究结果表明，OG 处理中优势细菌门为放线菌（Actinobacteria），相对丰度为 27.68%；WC 处理中优势细菌门为变形菌门（Proteobacteria），相对丰度为 25.89%。有机物质输入刺激了放线菌、厚壁菌门、绿弯菌门、子囊菌门和芽孢杆菌属、芽胞杆菌属、链霉菌属和青霉菌属的生长。有趣的是，与 CT 处理相比，OG 和 WC 处理分别促进了真菌和细菌的α多样性。此外，与 CT 处理相比，OG 处理有利于 C 循环酶活性的增加，而 WC 处理则倾向于增加 N 循环酶活性。值得注意的是，与 CT 处理相比，它们都富集了碳固定和循环途径基因，而 WC 处理增加了氮代谢途径基因。此外，与 CT 处理相比，OG 处理更有利于富集与纤维素和半纤维素水解有关的碳水化合物酶基因，而 WC 处理则增加了氮代谢途径基因。总之，不同质量的植物残体刺激了土壤微生物群落结构和功能的特定表达。长期种植白三叶草是改善土壤质量的有效策略。
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