Microbial crop residue decomposition dynamics in organic and conventionally managed soils
Microbial crop residue decomposition dynamics in organic and conventionally managed soils
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DOI：
10.1016/j.apsoil.2016.07.001
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发表时间：
2016-11-01
影响因子：
4.8
通讯作者：
Lemke, Reynald L.
中科院分区：
文献类型：
--
作者：
Arcand, Melissa M.;Helgason, Bobbi L.;Lemke, Reynald L.
农业实践可以影响土壤微生物群落，土壤微生物群落是土壤碳和养分循环过程的主要调节者。微生物群落组成的差异有可能影响分解过程中碳和养分的命运，因此可能影响农业生态系统中碳的保留和作物养分的供应。长期管理引起的微生物群落和资源可用性的变化可能会相互作用，在短期内影响微生物对作物残留物新鲜投入的利用，并对土壤碳累积和肥力产生持久影响。本研究的目的是调查长期有机管理和常规管理是否会导致微生物残留分解的差异。从加拿大萨斯喀彻温省的一项长期（19 年）田间研究中收集了种植一年生作物或一年生作物与三年生紫花苜蓿混合种植的常规和有机管理土壤，并在含有和不含有 C-13 标记的大麦残留物的实验室中培养 98 天。我们测量了分解过程中细胞外酶活性 (EEA) 以及主要微生物群（真菌、放线菌、革兰氏阳性菌和阴性菌）中农作物残留物来源的 C 的掺入情况。总 PLFA 生物量和 EEA 在常规一年生系统的土壤中最高，常规和有机多年生系统之间相似，而有机一年生系统中相似或最低。作物残渣的添加缓解了这些差异；也就是说，与未改良的土壤相比，在残留物改良的土壤中，有机系统中的总 PLFA 生物量、EEA 和真菌生物标志物的丰度有所增加，变得与传统系统相似。相比之下，添加残留物对常规一年生土壤中的生物量和 EEA 造成很小的变化或没有变化。使用 C-13-PLFA-SIP，我们表明土壤中分解过程中微生物演替的一般模式是相似的，但与传统管理的土壤相比，在分解的早期和后期阶段，真菌，尤其是放线菌在有机物中相对占主导地位。因此，在源自有机管理的土壤中，分解者群落组成的变化更大，这可能是由于培养过程中资源可用性发生了更大的变化，从而提高了微生物的演替速度。这可能会加剧管理制度之间 SOC 质量和养分可用性的长期差异。有机管理的耕作系统特别依赖有机养分的生物循环来支持作物生长。这项工作强调了充分的农作物残留物回报对于维持土壤功能的重要性，特别是在不使用外部有机改良剂来平衡作为农作物产品出口的养分的情况下。皇冠版权所有 (C) 2016 由 Elsevier B.V. 出版。保留所有权利。
Agricultural practices can influence soil microbial communities, which are the primary regulators of soil carbon and nutrient cycling processes. Differences in microbial community composition have the potential to affect the fate of carbon and nutrients during decomposition and may therefore influence the retention of C and provisioning of crop nutrients in agroecosystems. Long term management-induced shifts in microbial communities and resource availability may interact to affect the microbial utilization of fresh inputs of crop residues in the short term, with lasting impacts on soil C accrual and fertility. The objective of this study was to investigate whether long-term organic and conventional management resulted in differences in microbial residue decomposition. Soils under conventional and organic management planted with annual crops or with a mix of annual crops and three years of perennial alfalfa were collected from a long-term (19 y) field study in Saskatchewan, Canada and were incubated in the laboratory with and without C-13-labelled barley residues for 98 d. We measured extracellular enzyme activities (EEAs) and the incorporation of crop residue-derived C within major microbial groups (fungi, actinobacteria, and Gram positive and negative bacteria) during decomposition. Total PLFA biomass and EEAs were highest in soils from the conventional-annual system, similar between the conventional and organic perennial systems, and similar or lowest in the organic-annual system. Crop residue additions alleviated these differences; that is, in residue-amended soils total PLFA biomass, EEAs, and the abundance of the fungal biomarker increased in the organic systems compared to the unamended soils to become similar to the conventional systems. In contrast, residue additions induced small or no changes in biomass and EEAs in the conventional-annual soils. Using C-13-PLFA-SIP we showed that the general pattern of microbial succession during decomposition was similar among soils, but that fungi and especially actinobacteria were relatively more dominant in organic compared to conventionally managed soils during early and later stages of decomposition, respectively. Thus, shifts in the decomposer community composition were greater in soils originating from organic management, possibly as a result of larger changes in resource availability during the incubation that advanced the rate of microbial succession. This may reinforce long term differences in SOC quality and nutrient availability between management regimes. Organically-managed cropping systems are particularly reliant on biological cycling of organic nutrients to support crop growth. This work reinforces the importance of adequate crop residue returns for maintaining soil function, particularly where external organic amendments are not applied to balance nutrients exported as crop products. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.