McDonald Mark D, Lewis Katie L, Gentry Terry J
Department of Soil and Crop Sciences, Texas A&M University, College Station, Texas, USA.
Department of Natural Resources and the Environment, Center of Soil Biogeochemistry and Microbial Ecology, University of New Hampshire, Durham, New Hampshire, USA.
Appl Environ Microbiol. 2025 Apr 23;91(4):e0018425. doi: 10.1128/aem.00184-25. Epub 2025 Mar 10.
Managing soils in semi-arid agricultural croplands generally focuses on reducing wind erosion, increasing fertility, and storing carbon. Thus, converting conventionally tilled systems to no-tillage and cover-cropped systems are often the first steps towards a conservation management approach across the growing area of semi-arid croplands. From a soil biological perspective, introducing cover crops to semi-arid soils has been shown to alter microbial community structure, which may lead to changes in the biogeochemical pathways expressed in these soils. In this study, we examined the impact of single-species wheat cover cropping and no-tillage on microbial gene expression after 4 and 5 years of implementation. We sequenced the metatranscriptomes of three production systems with varying levels of conservation management: conventional tillage winter fallow, no-tillage winter fallow, and no-tillage with a winter wheat cover crop. Removing tillage was the biggest factor altering microbial gene expression in this study, specifically resulting in upregulation of several photosystem-associated functions. These functions were taxonomically linked to organisms that make up the early stages of biological soil crusts, which may introduce additional benefits to these semi-arid agricultural systems beyond a reduction in wind erosion. Implementing a cover crop did not clearly alter gene expression beyond the effect of tillage removal; however, it did indicate a potential to reduce fungal disease incidence in 1 year of the study. These alterations of microbial activities and selection for potentially beneficial functions should be considered and further studied to aid in maintaining sustainable croplands for our changing climate.IMPORTANCEEliminating tillage from semi-arid agricultural soils has the potential to significantly alter the activities of the soil bacterial community compared with conventionally tilled soils. A major driver of this change was the activities of biological soil crust forming organisms that can provide several environmental benefits to the soil ecosystem beyond the typically associated benefits of conservation management. Furthermore, this study revealed that the implementation of a cover crop regime on no-tillage soils does not confer a major change in the function of the organisms present. Overall, the study reported here reveals that soil management practices aimed at reducing wind erosion and improving sustainability will positively impact the function of the microbial community and suggests that future investigations into the consequences of these functional changes may provide valuable services to these agricultural ecosystems.
在半干旱农田中管理土壤通常侧重于减少风蚀、提高肥力和储存碳。因此，将传统耕作系统转变为免耕和覆盖作物系统往往是半干旱农田种植区采用保护性管理方法的第一步。从土壤生物学角度来看，在半干旱土壤中引入覆盖作物已被证明会改变微生物群落结构，这可能导致这些土壤中生物地球化学途径的变化。在本研究中，我们考察了实施4年和5年后，单一种类小麦覆盖作物种植和免耕对微生物基因表达的影响。我们对三种具有不同保护管理水平的生产系统的元转录组进行了测序：传统耕作冬闲、免耕冬闲以及免耕并种植冬小麦覆盖作物。在本研究中，去除耕作是改变微生物基因表达的最大因素，具体表现为上调了几种与光系统相关的功能。这些功能在分类学上与构成生物土壤结皮早期阶段的生物相关，这可能为这些半干旱农业系统带来除减少风蚀之外的额外益处。实施覆盖作物除了去除耕作的影响外，并没有明显改变基因表达；然而，在研究的1年中，它确实显示出降低真菌病害发生率的潜力。应考虑并进一步研究这些微生物活动的改变以及对潜在有益功能的选择，以帮助维持适应气候变化的可持续农田。重要性与传统耕作土壤相比，从半干旱农业土壤中消除耕作有可能显著改变土壤细菌群落的活动。这种变化的一个主要驱动因素是形成生物土壤结皮的生物的活动，它们除了能带来保护性管理通常具有的益处外，还能为土壤生态系统提供多种环境效益。此外，本研究表明，在免耕土壤上实施覆盖作物制度并不会使现存生物的功能发生重大变化。总体而言，本研究表明，旨在减少风蚀和提高可持续性的土壤管理措施将对微生物群落的功能产生积极影响，并表明未来对这些功能变化后果的研究可能为这些农业生态系统提供有价值的服务。
