Effect of simulated tillage on microbial autotrophic CO2 fixation in paddy and upland soils.

Xiaohong Wu,Jinshui Wu,Hongzhao Yuan,Zhenke Zhu,Wei Wang,Tida Ge,Qiong Liu,A S Whiteley

doi:10.1038/srep19784

Xiaohong Wu, Jinshui Wu + Show 6 more

Open Access

https://doi.org/10.1038/srep19784

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Abstract

Tillage is a common agricultural practice affecting soil structure and biogeochemistry. To evaluate how tillage affects soil microbial CO2 fixation, we incubated and continuously labelled samples from two paddy soils and two upland soils subjected to simulated conventional tillage (CT) and no-tillage (NT) treatments. Results showed that CO2 fixation (14C-SOC) in CT soils was significantly higher than in NT soils. We also observed a significant, soil type- and depth-dependent effect of tillage on the incorporation rates of labelled C to the labile carbon pool. Concentrations of labelled C in the carbon pool significantly decreased with soil depth, irrespective of tillage. Additionally, quantitative PCR assays revealed that for most soils, total bacteria and cbbL-carrying bacteria were less abundant in CT versus NT treatments, and tended to decrease in abundance with increasing depth. However, specific CO2 fixation activity was significantly higher in CT than in NT soils, suggesting that the abundance of cbbL-containing bacteria may not always reflect their functional activity. This study highlights the positive effect of tillage on soil microbial CO2 fixation, and the results can be readily applied to the development of sustainable agricultural management.

Highlights

Of tillage[20,21]
Advances in molecular microbial ecology allow us to investigate the function of soil autotrophic bacteria by quantifying cbbL gene abundances[24] and their associated CO2 fixation rates under different tillage managements
Using continuous labelling with 14CO2, we quantified the carbon fixed by soil autotrophs (14C-SOC), the distribution of newly assimilated carbon in the soil microbial biomass carbon pool (14C-MBC), and the dissolved organic carbon pool (14C-DOC) at different depths (0–1, 1–5, and 5–17 cm) of both conventional tillage treatment soils (CT) and no-till treatment soils (NT) soils

Summary

Introduction

Of tillage[20,21]. Despite intensive studies concerning the impact of different tillage practices on soil bacterial communities, we still have limited knowledge about the ecological functions of specific microbial communities under various tillage managements. Advances in molecular microbial ecology allow us to investigate the function of soil autotrophic bacteria by quantifying cbbL gene abundances[24] and their associated CO2 fixation rates under different tillage managements. This method fills a major knowledge gap in clarifying the effects of tillage upon important global C sequestration processes. The objective of this study was to evaluate the effect of different tillage practices on soil autotrophic bacterial populations and their CO2 assimilation rates at varying soil depths. We hypothesised that the mechanical disturbance from CT practices would decrease soil autotrophic bacterial abundance, leading to lower rates of CO2 fixation when compared with NT soils

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