Table_1_Microbial Communities Associated With Long-Term Tillage and Fertility Treatments in a Corn-Soybean Cropping System.DOCX

Tillage and fertilization are common practices used to enhance soil fertility and increase yield. Changes in soil edaphic properties associated with different tillage and fertility regimes have been widely examined, yet, the microbially mediated pathways and ecological niches involved in enhancing soil fertility are poorly understood. The effects of long-term conventional tillage and no-till in parallel with three fertility treatments (No fertilization, N-only, and NPK) on soil microbial communities were investigated in a long-term field study that was established in the 1970’s. Here, we used high-throughput sequencing of bacterial, fungal and oomycetes markers, followed by community-level functional and ecological assembly to discern principles governing tillage and fertility practices’ influence on associated soil microbiomes. Both tillage and fertilizer significantly altered microbial community structure, but the tillage effect was more prominent than the fertilizer effect. Tillage significantly affected bacteria, fungi, fusaria, and oomycete beta-diversity, whereas fertilizer only affected bacteria and fungi beta-diversity. In our study different tillage and fertilizer regimes favored specific networks of metabolic pathways and distinct ecological guilds. No-till selected for beneficial microbes that translocate nutrients and resources and protect the host against pathogens. Notably, ecological guilds featuring arbuscular mycorrhizae, mycoparasites, and nematophagous fungi were favored in no-till soils, while fungal saprotrophs and plant pathogens dominated in tilled soils. Conventional till and fertilizer management shifted the communities toward fast growing competitors. Copiotrophic bacteria and fusarium species were favored under conventional tillage and in the presence of fertilizers. The analysis of the metagenomes revealed a higher abundance of predicted pathways associated with energy metabolism, translation, metabolism of cofactors and vitamins, glycan biosynthesis and nucleotide metabolism in no-till. Furthermore, no specific pathways were found to be enriched under the investigated fertilization regimes. Understanding how tillage and fertilizer management shift microbial diversity, structure and ecological niches, such as presented here, can assist with designing farming systems that can maintain high crop yield, while reducing soil erosion and nutrient losses.

耕作与施肥是旨在提升土壤肥力和增加产量的常见农作实践。与不同耕作与肥力制度相关的土壤生态学特性变化已得到广泛研究，然而，涉及提升土壤肥力的微生物介导途径和生态位却鲜为人知。本研究对长期常规耕作与免耕（与三种肥力处理方式——不施肥、仅施氮肥和NPK肥——并行）对土壤微生物群落的影响进行了调查，该调查是在20世纪70年代建立的一个长期田间试验中进行的。本研究采用高通量测序技术对细菌、真菌和卵菌门标记物进行测序，随后通过群落水平的功能和生态组装分析，揭示耕作与肥力实践对相关土壤微生物群落的调控原理。耕作与施肥均显著改变了微生物群落结构，但耕作的影响相较于施肥更为显著。耕作对细菌、真菌、镰刀菌和卵菌门的β多样性产生显著影响，而施肥仅对细菌和真菌的β多样性产生影响。在本研究中，不同的耕作与施肥制度有利于特定的代谢途径网络和独特的生态群。免耕有利于选择那些能够迁移营养物质和资源、保护宿主免受病原体侵害的有益微生物。值得注意的是，在免耕土壤中，具有丛枝菌根、真菌寄生生物和食菌真菌特征的生态群得到了青睐，而在耕作土壤中，真菌分解者和植物病原体占据主导地位。常规耕作和施肥管理促使群落向快速生长的竞争者转变。在常规耕作和施肥条件下，富营养细菌和镰刀菌类物种得到了青睐。对宏基因组数据的分析揭示了在免耕条件下，与能量代谢、翻译、辅因子和维生素代谢、糖类生物合成和核苷酸代谢相关的预测途径的丰度较高。此外，在所研究的肥力制度下，并未发现任何特定的途径得到显著富集。了解耕作与施肥管理如何改变微生物多样性、结构和生态位，如本研究所展示的，有助于设计能够维持高作物产量、同时减少土壤侵蚀和养分损失的现代农业生产体系。