Since tillage can reduce the amount of organic C stored in soils, the use of conservation tillage practices, which exclude soil inversion, or include it less frequently, is often promoted. Soil microorganisms are closely linked to soil organic C (SOC), and they are assumed to respond quicker to management changes than SOC. Using two Swedish long-term tillage experiments, our aim was to determine whether (i) continuous conservation tillage (harrowing, H) increase microbial biomass (indicated by fatty acid signatures) compared to plowing (P), and if occasionally tilled soil (HP) was more like H or P. Also, the aim was to determine whether (ii) crop residue management has different effects on microbial biomass depending on tillage management, and whether (iii) conservation tillage and residue return increase SOC. We found that arbuscular mycorrhizal fungi (AMF) were stimulated by the H treatment compared to P treatment in the upper soil layer, and that occasional plowing resulted in intermediate amounts of AMF. The amount of microbial saprotrophs, on the other hand, was not affected by tillage treatment, and neither was the SOC concentration. Whether crop residues were returned in the autumn or not, had no direct effect on the microbial saprotrophs or the SOC after the winter, but crop residue removal stimulated AMF close to the surface in the P treatment. Although more research is needed to fully understand agricultural tillage and residue management effects on SOC dynamic, our study suggests that reducing or omitting plowing influence soil microbes, but does not necessarily result in more SOC.

中文翻译：

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生化特征揭示保护性耕作对丛枝菌根真菌的积极影响，但对腐生真菌和细菌没有积极影响

由于耕作可以减少土壤中储存的有机碳量，因此经常提倡使用保护性耕作做法，排除土壤倒转或不那么频繁地包括它。土壤微生物与土壤有机碳 (SOC) 密切相关，并且假定它们比 SOC 对管理变化的反应更快。使用两个瑞典的长期耕作实验，我们的目标是确定 (i) 与耕作 (P) 相比，持续保护性耕作 (Harrowing, H) 是否增加微生物生物量（由脂肪酸特征表示），如果偶尔耕作土壤 (HP ) 更像 H 或 P。此外，目的是确定 (ii) 作物残留管理是否对取决于耕作管理的微生物生物量有不同的影响，以及 (iii) 保护性耕作和残留物回收是否会增加 SOC。我们发现，在上层土壤中，与 P 处理相比，H 处理刺激了丛枝菌根真菌 (AMF)，偶尔翻耕会产生中等量的 AMF。另一方面，微生物腐生菌的数量不受耕作处理的影响，SOC 浓度也不受影响。秋季是否返还作物残茬，对冬季后的微生物腐生菌或SOC没有直接影响，但在P处理中，作物残茬的去除刺激了靠近地表的AMF。虽然需要更多的研究来充分了解农业耕作和残留管理对 SOC 动态的影响，但我们的研究表明，减少或省略耕作会影响土壤微生物，但不一定会导致更多的 SOC。