The dominant microorganisms vary with aggregates sizes in promoting soil carbon accumulation under straw application

Jinjing Lu,Shengping Li,Xueping Wu,Guopeng Liang,Chunhua Gao,Jianhua Li,Dongsheng Jin,Bisheng Wang,Mengni Zhang,Fengjun Zheng,Aurore Degré

doi:10.1080/03650340.2021.1955354

Abstract

ABSTRACT Unraveling the influence of microbes on C content at aggregate scale is pivotal for promoting soil C accumulation. Previous studies were based mainly on the mutual transformation process between aggregates, the links between the microorganisms in initial aggregates and inner C content and aggregate sizes were still unclear. In this study, the classified aggregates (> 5 mm, 2–5 mm, 1–2 mm, 0.25–1 mm, and < 0.25 mm) were individually incubated for 10 months under 13C-labeled maize straw application to analyze the relationship between microbial community structure in independent aggregates and inner C accumulation under straw addition. The results show that the SOC content increased in independent aggregates under straw addition, with higher stable C accumulation in < 0.25 mm than in > 2 mm aggregates. Aggregates of > 5 mm were more capable of improving unstable C accumulation and C derived from straw (Cstraw) than smaller aggregates. Fungi and Gram-negative bacteria (G-) were more important to increasing C accumulation in > 2 mm aggregates, whereas Gram-positive (G+) bacteria dominated in < 2 mm aggregates. The results indicate that the contribution of microorganisms within aggregates to inner C accumulation was associated with aggregate sizes.

Highlights

Terrestrial soils contain approximately three times the stock of carbon (C) of the atmosphere; small changes in soil organic carbon (SOC) have a significant impact on climate change [1]
In NP, NPS, and NPM, there were no differences in SOC contents among all aggregates.Microbial biomass carbon (MBC) and ROC contents were significantly affected by fertilization and aggregate size, respectively (p < 0.001; Table 2)
The four treatments had no significant differences in ROC and MBC contents (Figure 1C,D)

Summary

Introduction

Terrestrial soils contain approximately three times the stock of carbon (C) of the atmosphere; small changes in soil organic carbon (SOC) have a significant impact on climate change [1]. Among the numerous drivers that regulate the SOC pool, microorganisms are essential for SOC turnover [2]. Microorganisms have been reported to promote the formation of macro-aggregates to physically protect C, and their residues are considered to constitute an important source of stable C. It is reported that over half of the cumulative CO2 -C emitted from soil was induced by microbial community [4]. As such, understanding the contribution of microorganissms and enzymes to the accumulation or consumption of SOC in soil is of utmost importance for regulating soil C and reducing the impact of CO2 on the climate system

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Conclusion