Abstract
The objective of this study was to investigate how the relationships between bacterial communities and organic C (SOC) in topsoil (0–5 cm) are affected by tillage practices [conventional intensive tillage (CT) or no-tillage (NT)] and straw-returning methods [crop straw returning (S) or removal (NS)] under a rice-wheat rotation in central China. Soil bacterial communities were determined by high-throughput sequencing technology. After two cycles of annual rice-wheat rotation, compared with CT treatments, NT treatments generally had significantly more bacterial genera and monounsaturated fatty acids/saturated fatty acids (MUFA/STFA), but a decreased gram-positive bacteria/gram-negative bacteria ratio (G+/G−). S treatments had significantly more bacterial genera and MUFA/STFA, but had decreased G+/G− compared with NS treatments. Multivariate analysis revealed that Gemmatimonas, Rudaea, Spingomonas, Pseudomonas, Dyella, Burkholderia, Clostridium, Pseudolabrys, Arcicella and Bacillus were correlated with SOC, and cellulolytic bacteria (Burkholderia, Pseudomonas, Clostridium, Rudaea and Bacillus) and Gemmationas explained 55.3% and 12.4% of the variance in SOC, respectively. Structural equation modeling further indicated that tillage and residue managements affected SOC directly and indirectly through these cellulolytic bacteria and Gemmationas. Our results suggest that Burkholderia, Pseudomonas, Clostridium, Rudaea, Bacillus and Gemmationas help to regulate SOC sequestration in topsoil under tillage and residue systems.
Highlights
As crop residues[13,14,15]
Further investigation is needed to understand the relative contributions of soil bacterial communities to Soil organic C (SOC) and how these relationships may vary under different tillage practices
This study investigated the effects of tillage practices and straw-returning methods on soil bacterial communities and their relation to SOC after a 2-year rice-wheat cropping cycle in central China
Summary
As crop residues[13,14,15]. Tillage practices and straw-returning methods affect the activity and community structure of soil microorganisms by changing the habitat characteristics for soil microorganisms such as soil porosity, soil moisture and the substrates for soil microorganisms[16], affecting SOC dynamics in soil ecosystem. Most of previous studies focused on the effects of tillage practices and straw-returning methods on soil bacterial abundance, and consistently showed that both NT and S practices can increase soil bacterial abundance[7,22]. Guo et al.[1] reported the relationships between microbial metabolic characteristics and SOC within aggregates under different tillage practices and straw-returning methods, and indicated that the increased SOC in aggregates in the topsoil under NT and S practices was possibly due to the improvement of microbial metabolic activities. The objective of this study was to assess the effects of tillage practices (i.e. NT and CT) and straw returning methods (i.e. crop residue removal (S) and returning (NS)) on topsoil bacterial communities and their relationships with SOC under rice-wheat cropping system in central China. Structural equation modeling (SEM) was used to detect the potential associations among tillage systems/straw systems, bacterial communities and SOC
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