Mixing crop residues induces a synergistic effect on microbial biomass and an additive effect on soil organic matter priming
Mixing crop residues induces a synergistic effect on microbial biomass and an additive effect on soil organic matter priming
复制标题
DOI：
10.1101/2021.05.11.443543
复制
发表时间：
2021-05
期刊：
影响因子：
--
通讯作者：
Xin Shu;Yiran Zou;L. Shaw;L. Todman;M. Tibbett;T. Sizmur
中科院分区：
文献类型：
--
作者：
Xin Shu;Yiran Zou;L. Shaw;L. Todman;M. Tibbett;T. Sizmur
施用农作物残体是一种广泛使用的增加土壤有机质的策略，因为它记录了增加微生物生物量和坏死量的效果。然而，新鲜残留物的输入也可以“总理”的本地SOM的分解，导致加速SOM的枯竭和温室气体（GHG）排放。增加种植在可耕地系统中的作物的植物多样性，以增加多种生态功能的提供，包括增加土壤微生物生物量和SOM。在混养中生长的不同作物的新鲜残留物的混合物对土壤碳（C）库的贡献是否比施用单独残留物所预期的更大（即，该混合物产生非加和的协同效应）尚未系统地测试，并且目前是未知的。在这项研究中，我们使用13 C同位素标记的覆盖作物残留物（即，荞麦、三叶草、萝卜和向日葵），以追踪植物残留物来源的C和来源于在实验室微观实验中在包含残留物的四元混合物的处理中引发SOM的C的命运，以及残留物掺入后一天四种单独残留物的平均效应。我们的研究结果表明，尽管所有处理都接受了相同数量的植物残体来源的C（1 mg-1 C g土壤），但接受残体混合物的处理中的总微生物生物量显着高于26%（3.69 µg-1 C g），比在施用作物残体后一天接受混合物的四种单独组分的处理中观察到的平均微生物生物量。与单个残留物处理的平均值相比，四元混合物中的微生物生物量C更大，这可以直接归因于施用的植物残留物，也显著更大，增加了132%（3.61 µg-1 C g）。然而，没有证据表明，该混合物导致任何更多的启动本地SOM比平均启动中观察到的个别残留物处理。土壤微生物群落结构，使用磷脂脂肪酸（PLFA）分析评估，是显着（P < 0.001）不同的土壤接收残留物的混合物，相比，在土壤中接受四个单独的残留物的群落的平均结构。真菌、普通细菌和革兰氏阳性细菌生物量的差异是作物残留物混合物对总微生物生物量和残留物衍生的微生物生物量的协同效应的原因，特别是生物标志物16：0、18：2ω6和18：3ω3。我们的研究表明，施用作物残留物的混合物增加土壤微生物生物量的程度比预期的应用单个残留物，这是由于更快的作物残留物的分解或更高的碳利用效率（CUE），而不是启动本地SOM的分解。因此，种植作物多元文化（例如，覆盖作物混合物）和将所得作物残留物的混合物掺入土壤中可能是增加可耕地土壤中微生物生物量并最终增加碳储量的有效方法。
Applying crop residues is a widely used strategy to increase soil organic matter (SOM) in arable soils because of its recorded effects on increasing microbial biomass and consequently necromass. However, fresh residue inputs could also “prime” the decomposition of native SOM, resulting in accelerated SOM depletion and greenhouse gas (GHG) emission. Increasing the botanical diversity of the crops grown in arable systems has been promoted to increase the delivery of multiple ecological functions, including increasing soil microbial biomass and SOM. Whether mixtures of fresh residues from different crops grown in polyculture contribute to soil carbon (C) pools to a greater extent than would be expected from applying individual residues (i.e., the mixture produces a non-additive synergistic effect) has not been systematically tested and is currently unknown. In this study, we used 13C isotope labelled cover crop residues (i.e., buckwheat, clover, radish, and sunflower) to track the fate of plant residue-derived C and C derived from the priming of SOM in treatments comprising a quaternary mixture of the residues and the average effect of the four individual residues one day after residue incorporation in a laboratory microcosm experiment. Our results indicate that, despite all treatments receiving the same amount of plant residue-derived C (1 mg-1 C g soil), the total microbial biomass in the treatment receiving the residue mixture was significantly greater, by 26% (3.69 µg-1 C g), than the average microbial biomass observed in treatments receiving the four individual components of the mixture one day after applying crop residues. The greater microbial biomass C in the quaternary mixture, compared to average of the individual residue treatments, that can be attributed directly to the plant residue applied was also significantly greater, by 132% (3.61 µg-1 C g). However, there was no evidence that the mixture resulted in any more priming of native SOM than average priming observed in the individual residue treatments. The soil microbial community structure, assessed using phospholipid fatty acid (PLFA) analysis, was significantly (P < 0.001) different in the soil receiving the residue mixture, compared to the average structures of the communities in soil receiving four individual residues. Differences in the biomass of fungi, general bacteria, and Gram-positive bacteria were responsible for the observed synergistic effect of crop residue mixtures on total microbial biomass and residue-derived microbial biomass, especially biomarkers 16:0, 18:2ω6 and 18:3ω3. Our study demonstrates that applying a mixture of crop residues increases soil microbial biomass to a greater extent than would be expected from applying individual residues and that this occurs either due to faster decomposition of the crop residues or greater carbon use efficiency (CUE), rather than priming the decomposition of native SOM. Therefore, growing crop polycultures (e.g., cover crop mixtures) and incorporating mixtures of the resulting crop residues into the soil could be an effective method to increase microbial biomass and ultimately C stocks in arable soils.