Cover Crop Management Practices Rather Than Composition of Cover Crop Mixtures Affect Bacterial Communities in No-Till Agroecosystems - PubMed (original) (raw)

Cover Crop Management Practices Rather Than Composition of Cover Crop Mixtures Affect Bacterial Communities in No-Till Agroecosystems

Sana Romdhane et al. Front Microbiol. 2019.

Abstract

Cover cropping plays a key role in the maintenance of arable soil health and the enhancement of agroecosystem services. However, our understanding of how cover crop management impacts soil microbial communities and how these interactions might affect soil nutrient cycling is still limited. Here, we studied the impact of four cover crop mixtures varying in species richness and functional diversity, three cover crop termination strategies (i.e., frost, rolling, and glyphosate) and two levels of irrigation at the cover crop sowing on soil nitrogen and carbon dynamics, soil microbial diversity, and structure as well as the abundance of total bacteria, archaea, and _N_-cycling microbial guilds. We found that total nitrogen and soil organic carbon were higher when cover crops were killed by frost compared to rolling and glyphosate termination treatments, while cover crop biomass was positively correlated to soil carbon and C:N ratio. Modifications of soil properties due to cover crop management rather than the composition of cover crop mixtures were related to changes in the abundance of ammonia oxidizers and denitrifiers, while there was no effect on the total bacterial abundance. Unraveling the underlying processes by which cover crop management shapes soil physico-chemical properties and bacterial communities is of importance to help selecting optimized agricultural practices for sustainable farming systems.

Keywords: bacterial diversity; conservation agriculture; cover crops; denitrifiers; nitrifiers; nitrogen cycling.

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Figures

FIGURE 1

FIGURE 1

Effects of the interaction between sampling time (T1, T2, and T3) and cover crop termination by frost, glyphosate, or rolling on soil (A) total nitrogen and (B) organic carbon. All values are means ± standard errors.

FIGURE 2

FIGURE 2

NMDS ordinations based on weighted unifrac distance matrix of soil bacterial community (stress value = 0.17). Ellipses show clustering of samples by sampling time. Significant explanatory variables are represented as arrows (PermANOVA, P < 0.001).

FIGURE 3

FIGURE 3

Heatmap plot representing correlation analysis between relative abundance of soil bacterial community at genus level and soil physico-chemical properties. Colors range from blue (low) to red (high) and represent negative to positive correlations, respectively.

FIGURE 4

FIGURE 4

Significant effects of the interaction between cover crop termination (frost, glyphosate, and rolling) and sampling time (T1, T2, and T3) on the abundance of N cycling communities. (A) nirK denitrifiers, (B) nirS denitrifiers, (C) nosZI denitrifiers, and (D) ammonia oxidizing archaea (AOA) (Log10 gene copy ng–1 DNA). All values are means ± standard errors.

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