Legacy of warming and cover crops on the response of soil microbial function to repeated drying and rewetting cycles
Legacy of warming and cover crops on the response of soil microbial function to repeated drying and rewetting cycles
复制标题
DOI：
10.1101/2023.12.21.571204
复制
发表时间：
2023-12
期刊：
影响因子：
--
通讯作者：
A. A. Adekanmbi-A.;Yiran Zou;Xin Shu;Giacomo Pietramellara;S. Pathan;Lindsay Todman;T. Sizmur
中科院分区：
文献类型：
--
作者：
A. A. Adekanmbi-A.;Yiran Zou;Xin Shu;Giacomo Pietramellara;S. Pathan;Lindsay Todman;T. Sizmur
土壤对极端天气事件的反应在今后将变得越来越重要，因为气候变化导致的更频繁和更严重的洪涝和干旱预计将使土壤经历干旱和再湿润的循环。这些极端事件将在整体变暖的背景下发生。然而，农民正在采用覆盖种植作为一种可持续的管理做法，以增加土壤有机质，有益于土壤健康，并提高土壤的复原力，以帮助减轻气候变化的影响。我们研究了气候变暖和覆盖作物对土壤微生物功能对反复干燥和再湿润循环的响应。我们引入了开顶室温暖的土壤表面的田间小区实验中，覆盖作物（单种单作和4种混作）种植在夏季收获后和种植前的秋季播种的经济作物在谷物轮作。土壤样品收集温暖和周围地区的实验地块在春天，收获之前的谷物作物。我们量化呼吸（土壤微生物功能的措施）与高频CO2通量测量后，0，1，2，4，或8湿/干周期施加在实验室和另外的比例为10毫克g-1土壤的大麦草粉基质。覆盖作物混合物在土壤中产生了负面的遗留效应，导致累积基质诱导的呼吸作用低于单作中生长的相同物种的平均值。重复干燥和再湿润循环增加了累积的基质诱导的呼吸速率观察，这表明，反复扰动选择一个社会适应更快地处理大麦苗粉。这种适应可能导致了更大的渗透压产生或reacquisition暴露于反复干旱事件的微生物。渗透调节剂在再湿润后迅速代谢，并且可能在之前暴露于干燥和再湿润循环的土壤中更大程度地促进了大麦芽粉的分解。当我们计算8个湿/干周期后的累积呼吸时，相对于0个湿/干周期后的累积呼吸（我们推断代表微生物群落适应重复干燥和再湿周期的程度），我们的数据显示，变暖的遗产显着减少，但覆盖作物显着增加，土壤微生物群落适应。这种适应的土壤微生物群落与水提取的有机碳在土壤中的浓度呈正相关，然后施加干燥和再润湿循环和/或添加基质。不稳定碳的可用性可能介导了微生物合成渗透调节剂以应对干旱的能力。我们的结论是，覆盖作物可能会提高土壤微生物群落的能力，以适应干旱事件，减轻气候变暖的影响，可能是由于提供不稳定的有机碳的渗透调节剂的合成。
The response of soils to extreme weather events will become increasingly important in the future as more frequent and severe floods and droughts are expected to subject soils to drying and rewetting cycles as a result of climate change. These extreme events will be experienced against a backdrop of overall warming. However, farmers are adopting cover cropping as a sustainable management practice to increase soil organic matter, benefit soil health, and to increase the resilience of soils to help mitigate the impacts of climate change. We examined the legacy of warming and cover crops on the response of soil microbial function to repeated drying and rewetting cycles. We introduced open top chambers to warm the soil surface of a field plot experiment in which cover crops (single species monocultures and 4-species polycultures) were grown over the summer after harvest and before planting of autumn sown cash crops in a cereal rotation. Soil samples were collected from warmed and ambient areas of the experimental plots in spring, before harvesting the cereal crop. We quantified respiration (a measure of soil microbial function) with high-frequency CO2 flux measurements after 0, 1, 2, 4, or 8 wet/dry cycles imposed in the laboratory and the addition of barley grass powder substrate at a ratio of 10 mg g-1 soil. Cover crop mixtures created a negative legacy effect in the soil which resulted in lower cumulative substrate induced respiration than expected from the average of the same species grown in monoculture. Repeated drying and rewetting cycles increased the cumulative substrate induced respiration rate observed, suggesting that repeated perturbations selected for a community adapted to processing the barley shoot powder more quickly. This adaptation may have resulted in a greater osmolyte production or reacquisition by microorganisms exposed to repeated drought events. Osmolytes are rapidly metabolised upon re-wetting and may have primed the decomposition of the barley shoot powder to a greater extent in soils previously exposed to drying and rewetting cycles. When we calculated the cumulative respiration after 8 wet/dry cycles, relative to cumulative respiration after 0 wet/dry cycles (which we infer represents the extent to which microbial communities adapted to repeated drying and rewetting cycles) our data revealed that the legacy of warming significantly reduced, but cover crops significantly increased, soil microbial community adaptation. This adaptation of the soil microbial community was positively correlated with the concentration of water extractable organic carbon in the soils prior to imposing the drying and rewetting cycles and/or adding the substrate. The availability of labile carbon may have mediated the ability of microorganisms to synthesise osmolytes in response to drought. We conclude that cover crops may enhance the ability of the soil microbial community to adapt to drought events and mitigate the impact of warming, possibly due to the provision of labile organic carbon for the synthesis of osmolytes.