Center for Agricultural Resources Research, Institute of Genetic and Developmental Biology, Chinese Academy of Science / Hebei Key Laboratory of Soil Ecology / Key Laboratory of Agricultural Water Resources, Chinese Academy of Sciences, Huaizhong Road 286, Shijiazhuang, 050022, China.
University of Chinese Academy of Sciences, Yuquan Road 19A, Beijing, 100049, China.
Sci Rep. 2021 Sep 17;11(1):18542. doi: 10.1038/s41598-021-97231-5.
The enzymatic activities and ratios are critical indicators for organic matter decomposition and provide potentially positive feedback to carbon (C) loss under global warming. For agricultural soils under climate change, the effect of long-term warming on the activities of oxidases and hydrolases targeting C, nitrogen (N) and phosphorus (P) and their ratios is unclear, as well as whether and to what extend the response is modulated by long-term fertilization. A 9-year field experiment in the North China Plain, including an untreated control, warming, N fertilization, and combined (WN) treatment plots, compared the factorial effect of warming and fertilization. Long-term warming interacted with fertilization to stimulate the highest activities of C, N, and P hydrolases. Activities of C and P hydrolase increased from 8 to 69% by N fertilization, 9 to 53% by warming, and 28 to 130% by WN treatment compared to control, whereas the activities of oxidase increased from 4 to 16% in the WN soils. Both the warming and the WN treatments significantly increased the enzymatic C:N ratio from 0.06 to 0.16 and the vector length from 0.04 to 0.12 compared to the control soil, indicating higher energy and resource limitation for the soil microorganisms. Compared to WN, the warming induced similar ratio of oxidase to C hydrolase, showing a comparable ability of different microbial communities to utilize lignin substrates. The relationship analyses showed mineralization of organic N to mediate the decomposition of lignin and enzyme ratio in the long-term warming soil, while N and P hydrolases cooperatively benefited to induce more oxidase productions in the soil subject to both warming and N fertilization. We conclude that coupled resource limitations induced microbial acclimation to long-term warming in the agricultural soils experiencing high N fertilizer inputs.
酶活性和比率是有机质分解的关键指标，在全球变暖下为碳（C）损失提供潜在的正反馈。对于气候变化下的农业土壤，长期变暖对针对 C、氮（N）和磷（P）的氧化酶和水解酶活性及其比率的影响尚不清楚，以及这种响应是否以及在多大程度上受到长期施肥的调节。在中国北方平原进行的一项为期 9 年的田间实验，包括未处理对照、增温、氮施肥和联合（WN）处理小区，比较了增温和施肥的综合效应。长期增温与施肥相互作用，刺激了 C、N 和 P 水解酶的最高活性。与对照相比，N 施肥使 C 和 P 水解酶的活性分别增加了 8%至 69%、9%至 53%，WN 处理则分别增加了 28%至 130%，而氧化酶的活性则在 WN 土壤中增加了 4%至 16%。与对照土壤相比，增温和 WN 处理均显著提高了酶促 C:N 比（从 0.06 增加到 0.16）和矢量长度（从 0.04 增加到 0.12），表明土壤微生物对能量和资源的限制更高。与 WN 相比，增温诱导了氧化酶与 C 水解酶的相似比例，表明不同微生物群落利用木质素底物的能力相当。相关分析表明，有机 N 的矿化介导了木质素的分解和长期增温土壤中酶的比率，而 N 和 P 水解酶的协同作用有利于在同时受到增温和 N 施肥的土壤中诱导更多的氧化酶产生。我们的结论是，在高氮肥投入的农业土壤中，耦合资源限制诱导了微生物对长期增温的适应。
