Abstract:

Microbial residues， as an important precursor for the formation of organic carbon， are crucial for the long-term sequestration and stabilization of carbon in farmland. In order to explore the effect of organic materials addition on microbial residues accumulation in Chinese farmland， a Meta-analysis of 111 sets of data on the content of amino sugars （microbial residue characterizing substances） from 27 published literatures were conducted and the effects of organic materials addition on the accumulation characteristics of amino sugars ［glucosamine （GluN）， galactosamine （GalN）， muraic acid （MurN） and total amino sugars］ in farmland were summarized， and the relative contribution of fungal and bacterial residues to soil organic matter were explored using the ratio of GluN to MurN （GluN/MurN） and GluN to GalN （GluN/GalN）. The results showed that the addition of organic materials significantly increased the accumulation of soil microbial residues， with soil amino sugars increasing by 27.7%， and GluN， GalN， MurN increasing by 26.8%， 24.1% and 24.2%， respectively. The accumulation of amino sugars and GluN， GalN， MurN by manure was significantly higher than that straw， with an increase from 28.4% to 37.6%. GluN， GalN， GluN/MurN and GluN/GalN were significantly higher when the average annual carbon input of the organic material was higher than 2 t·hm^-2·a^-1 than when the average annual carbon input was lower than 2 t·hm^-2·a^-1， with an increase of 41.8%， 41.1%， 8.3% and 4.1%， respectively； the increases in amino sugar， GluN and MurN （41.1%， 39.9% and 36.3%） were significantly higher when organic matter was added for more than 10 years than the experimental year below 10 years. Among the climatic factors， the accumulation of amino sugar content by added organic matter was significantly higher when the annual mean temperature was more than 10 ℃ （42.0%） and mean annual precipitation was more than 800 mm （63.0%） were significantly higher than those with annual mean temperature less than 5 ℃ （17.9%） and mean annual precipitation less than 800 mm （28.2% and 13.7%）. Among the soil factors， the highest accumulation of total soil amino sugars was observed in neutral soils （pH 6~8） and fertile soils （soil organic carbon content >12 g·kg^-1）， with an increase of 39.4% and 43.0%， respectively. Regression analysis showed that， within a certain range， soil microbial residues in farmland increased with the increase of mean annual precipitation， mean annual temperature， organic material application rate， organic material carbon input， and experimental years. In conclusion， the addition of organic materials， especially high carbon inputs， significantly increased the total amino sugars and amino monosaccharides contents of farmland. Fertile and neutral soils in warm and humid areas were favorable for the accumulation of soil microbial residues under organic materials application. Above results provided scientific basis for determining the optimal scenarios of adding organic materials for the accumulation of microbial residues in farmland in China， and for promoting the formation and sequestration of stabilized soil organic carbon.

Key words: organic materials, amino sugars, microbial residues, soil organic carbon, Meta-analysis

摘要：

微生物残体作为有机碳形成的重要前体，对农田土壤中碳的长期固存和稳定至关重要。为探讨有机物料添加对我国农田土壤微生物残体积累的影响，对来自27篇已发表文献的共111组氨基糖（微生物残体表征物质）含量数据进行整合分析，总结添加有机物料对农田土壤氨基糖［氨基葡萄糖（glucosamine，GluN）、氨基半乳糖（galactosamine，GalN）、胞壁酸（muraic acid，MurN）及氨基糖总量］的积累特征，并利用氨基葡萄糖与胞壁酸的比值（GluN/MurN）和氨基葡萄糖与氨基半乳糖（GluN/GalN）的比值探讨真菌和细菌残体对土壤有机质相对贡献的影响。结果表明，添加有机物料显著增加土壤微生物残体的积累，其中土壤氨基糖增幅27.7%，GluN、GalN和MurN 的增幅分别为26.8%、24.1%、24.2%。粪肥对氨基糖和3种单糖的积累显著高于秸秆，增幅为28.4%~37.6%；当有机物料的年均碳投入量高于2 t·hm^-2·a^-1时，GluN、GalN、GluN/MurN和GluN/GalN显著高于年均碳投入量低于2 t·hm^-2·a^-1，提高幅度分别为41.8%、41.1%、8.3%和4.1%；当添加有机物料的年限超过10 a时，氨基糖、GluN和MurN的增幅（41.1%、39.9%和36.3%）显著高于试验年限低于10 a。在气候因素中，添加有机物料对氨基糖含量的积累在年均温超过10 ℃（42.0%）和年降水大于800 mm（63.0%）时显著高于年均温小于5 ℃（17.9%）和年降水小于800 mm（28.2%和13.7%）。在土壤因素中，中性（pH 6~8）土壤和肥沃（土壤有机碳含量>12 g·kg^-1）土壤的土壤氨基糖总量的积累最高，增幅分别为39.4%和43.0%。回归分析表明，在一定范围内农田土壤微生物残体会随着年降水、年均温、有机物料施用量、有机物料碳投入量和试验年限的增加而增加。综上，添加有机物料，特别是高碳投入量显著增加了农田土壤总氨基糖和氨基单糖的含量。有机物料施用下，温暖湿润地区肥沃中性的土壤有利于促进土壤微生物残体的积累。研究结果为确定添加有机物料对我国农田土壤微生物残体积累的最佳情景、促进稳定土壤有机碳的形成和封存提供了科学依据。

关键词: 有机物料, 氨基糖, 微生物残体, 土壤有机碳, 整合分析