Abstract
Our understanding on the effects of tillage intensity on the soil microbial community structure and composition in crop production systems are limited. This study evaluated the soil microbial community composition and diversity under different tillage management systems in an effort to identify management practices that effectively support sustainable agriculture. We report results from a three-year study to determine the effects on changes in soil microbial diversity and composition from four tillage intensity treatments and two residue management treatments in a corn-soybean production system using Illumina high-throughput sequencing of 16S rRNA genes. Soil samples were collected from tillage treatments at locations in the Southern Coastal Plain (Verona, MS, USA) and Southern Mississippi River Alluvium (Stoneville, MS, USA) for soil analysis and bacterial community characterization. Our results indicated that different tillage intensity treatments differentially changed the relative abundances of bacterial phyla. The Mantel test of correlations indicated that differences among bacterial community composition were significantly influenced by tillage regime (rM = 0.39, p ≤ 0.0001). Simpson’s reciprocal diversity index indicated greater bacterial diversity with reduction in tillage intensity for each year and study location. For both study sites, differences in tillage intensity had significant influence on the abundance of Proteobacteria. The shift in the soil bacterial community composition under different tillage systems was strongly correlated to changes in labile carbon pool in the system and how it affected the microbial metabolism. This study indicates that soil management through tillage intensity regime had a profound influence on diversity and composition of soil bacterial communities in a corn-soybean production system.
Highlights
One study was established at North Mississippi Research and Extension Center, Verona, MS on a non-irrigated Fluvaquentic Eutrudepts (Marietta series), which is in the upper Southern Coastal Plain (SCP) major land resource area (MLRA); and another at Delta Research and Extension Center, Stoneville, MS on an irrigated Typic
At both the locations (SCP and Southern Mississippi River Alluvium (SMRA)), conservation tillage plots (Min and reduced intensity tillage (Red)) showed a significant higher water stable aggregate content than the conventionally tilled plots (Mod and High), especially in the second crop rotation cycle (2015) and registered significant higher soil resistance at minimum intensity tillage (Min)-till plots compared to all the other tillage treatments (Table 2)
Our results showed that bacterial community in conservation tillage (Min and Red) plots were more diverse in terms of evenness and richness
Summary
Soil disturbing agricultural practices, such as tillage and residue management operations have a direct influence on soil quality [1,2,3]. Soil quality captures an overall picture of soil functionality that includes chemical, physical and biological features necessary for long-term, sustainable productivity. The role and importance of soil quality for sustainable crop production is receiving increasing attention from both farmers and researchers [4,5]. Healthy soil maintains diverse microbial communities that have been shown to control plant diseases, effectively recycle plant nutrients, improve soil structure, and improve overall crop production [6,7]. Soils are highly heterogeneous both physico-chemically and biologically, thereby encompassing a wide range of niches available to sustain microbial
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