Carbon transfer from maize roots and litter into bacteria and fungi depends on soil depth and time
Carbon transfer from maize roots and litter into bacteria and fungi depends on soil depth and time
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DOI：
10.1016/j.soilbio.2015.10.015
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发表时间：
2016-02
影响因子：
9.7
通讯作者：
K. Müller;S. Kramer;Heike Haslwimmer;S. Marhan;Nicole Scheunemann;Olaf Butenschön;S. Scheu;E. Kandeler
中科院分区：
文献类型：
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作者：
K. Müller;S. Kramer;Heike Haslwimmer;S. Marhan;Nicole Scheunemann;Olaf Butenschön;S. Scheu;E. Kandeler
植物源碳(C)向土壤的转移是控制地下微生物群落大小和结构的重要因素之一。本研究量化了这种植物来源的碳在耕地表层和底土中进入非生物和生物碳库的时间超过5年。采用稳定同位素分析方法测定了玉米根冠凋落物C在土壤有机C （SOC）、可提取有机C （EOC）、微生物总生物量（Cmic）、麦角甾醇和磷脂脂肪酸（PLFAs）中的含量。以玉米（CM）、饲料玉米（FM）和小麦+玉米凋落物改良剂（WL）为对照，分别进行了根源和茎源C（不含玉米芯）的处理，根源C的处理和茎源C的处理。2009 - 2013年，每年9月直接在收获前采集土壤样本。试验期间，玉米源C信号在表层土壤（0 ~ 10 cm）的SOC、EOC、Cmic、麦角甾醇、细菌和真菌PLFAs中呈升高趋势。尽管玉米茎部总碳输入量是根系碳输入量的三倍，但玉米茎部和根系碳输入量相对相似，这表明茎部碳源对表层土壤微生物的重要性。在CM处理中，两种碳源均存在加性效应，各池中玉米来源的碳几乎增加了一倍。此外，玉米来源的碳在不同池中的比例也存在差异，5年后CM处理中，玉米来源的碳在表层土壤总SOC（17%）和总EOC（24%）池中的掺入率较低，而在不同微生物群（革兰氏阳性（Gr+）细菌PLFA-C中占29%，革兰氏阴性（Gr -）细菌PLFA-C中占44%，真菌PLFA-C中占69%，麦角甾醇中占78%）中的掺入率较高。在第3和第5个植被期后，我们还在有根区（40 ~ 50 cm）和无根区（60 ~ 70 cm）检测到玉米来源的碳。与表层土壤碳库相比，地下土壤碳库中玉米源碳的掺入量较低。在无根区，玉米来源的碳含量占总SOC的2%，总EOC的28%，Gr+细菌PLFA-C的9%，Gr -细菌PLFA-C的20%，真菌PLFA-C的53%。腐养真菌在所有土壤深度吸收玉米源碳的程度均高于Gr+和Gr -细菌，表明腐养真菌在该农业生态系统中的重要性。
Plant-derived carbon (C) transfer to soil is one of the important factors controlling the size and structure of the belowground microbial community. The present study quantifies this plant-derived C incorporation into abiotic and biotic C pools in top- and subsoil in an arable field over five years. Stable isotope analysis was used to determine the incorporation of maize root and shoot litter C into soil organic C (SOC), extractable organic C (EOC), total microbial biomass (Cmic), ergosterol and phospholipid fatty acids (PLFAs). The following treatments were investigated: corn maize (CM), providing root- and shoot-derived C (without corncobs), fodder maize (FM), providing only root-derived C, and wheat plus maize shoot litter amendment (WL), providing only shoot-derived maize C. Wheat plants (W) without maize litter amendment served as control. Soil samples were taken each September directly before harvest from 2009 to 2013. During the experiment, the maize-derived C signal increased in SOC, EOC, Cmic, ergosterol, bacterial and fungal PLFAs in the topsoil (0–10 cm). Although total maize shoot C input was threefold lower than maize root C input, similar relative amounts of maize C derived from shoots and roots were incorporated into the different C pools in the WL and the FM treatments, indicating the importance of shoot-derived C sources for microorganisms in the topsoil. An additive effect of both C sources was found in the CM treatment with almost twice as much maize-derived C in the respective pools. Furthermore, the proportion of maize-derived C varied between the different pools with lower incorporation into the total SOC (17%) and total EOC (24%) pools and higher incorporation ratios of maize C into PLFAs of different microbial groups (29% in Gram-positive (Gr+) bacterial PLFA-C, 44% in Gram-negative (Gr−) bacterial PLFA-C, 69% in fungal PLFA-C and 78% in ergosterol) in the CM treatment in topsoil after five years. After the third and fifth vegetation periods, we also detected maize-derived C in the rooted zone (40–50 cm depth) and the root-free zone (60–70 cm depth). The maize-derived C incorporation was lower in subsoil C pools in comparison to topsoil C pools. In the root-free zone, the maize-derived C was found to be 2% in total SOC, 28% in total EOC, 9% in Gr+bacterial PLFA-C, 20% in Gr−bacterial PLFA-C and 53% in fungal PLFA-C. Saprotrophic fungi incorporated maize-derived C in all soil depths to a greater degree than Gr+and Gr−bacteria, indicating the importance of saprotrophic fungi in this agro-ecosystem.