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

Sana Romdhane,Juliette Martin,Marie-Christine Breuil,Laurent Falchetto,Hugues Busset,Florian Bizouard,Stéphane Cordeau,Laurent Philippot,Aymé Spor,David Bru

doi:10.3389/fmicb.2019.01618

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.

Highlights

Agriculture faces several challenges to improve crop productivity, while ensuring ecosystem sustainability
Cover cropping, an old management practice, Cover Crop Management Affect Bacterial Communities is emerging as a challenging agricultural practice that can play a major role in enhancing sustainable agriculture and supporting ecosystem services (Schipanski et al, 2014; Groff, 2015)
Since we observed a spatial variability of some soil properties in the experimental field that was not related to the studied treatments, a block effect and an “Y-position in the field” effect were included in our analysis of variance (ANOVA) model for distinguishing the effects of the studied treatments from those of the spatial structuring of soil properties

Summary

Introduction

Agriculture faces several challenges to improve crop productivity, while ensuring ecosystem sustainability. Ecosystem services provided by cover crops include protecting soils from erosion and reducing soil nutrient losses by leaching and run-off (Kuo and Sainju, 1998). Cover crops can modify soil properties by increasing organic matter where there are mixtures with a high C:N ratio, total nitrogen where there are legume-based mixtures, and in all cases enhancing soil nutrients available for succeeding crops (Hubbard et al, 2013). A recent study reported that cover cropping has positive effects on plant production leading to an increase in crop yields up to 24% in reduced tillage organic systems but only of 2% in conventional system with tillage (Wittwer et al, 2017)

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