Steering microbiomes by organic amendments towards climate-smart agricultural soils

Kristof Brenzinger,Gerard Korthals,Ohana Y A Costa,Douwe Molenaar,Bjorn Robroek,Paul L E Bodelier,Guusje Koorneef,Adrian Ho

doi:10.1007/s00374-021-01599-5

Abstract

We steered the soil microbiome via applications of organic residues (mix of cover crop residues, sewage sludge + compost, and digestate + compost) to enhance multiple ecosystem services in line with climate-smart agriculture. Our result highlights the potential to reduce greenhouse gases (GHG) emissions from agricultural soils by the application of specific organic amendments (especially digestate + compost). Unexpectedly, also the addition of mineral fertilizer in our mesocosms led to similar combined GHG emissions than one of the specific organic amendments. However, the application of organic amendments has the potential to increase soil C, which is not the case when using mineral fertilizer. While GHG emissions from cover crop residues were significantly higher compared to mineral fertilizer and the other organic amendments, crop growth was promoted. Furthermore, all organic amendments induced a shift in the diversity and abundances of key microbial groups. We show that organic amendments have the potential to not only lower GHG emissions by modifying the microbial community abundance and composition, but also favour crop growth-promoting microorganisms. This modulation of the microbial community by organic amendments bears the potential to turn soils into more climate-smart soils in comparison to the more conventional use of mineral fertilizers.

Highlights

Atmospheric concentrations of the major greenhouse gases (GHG), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), have increased since the industrial revolution by 40%, 150%, and 20%, respectively (Sohngen and Tian 2016; IPCC 2018); approximately 50% and 60%, respectively for CH4 and N2O of these GHG emissions originated from agriculture (Tian et al 2016)
Systematic studies exploring the interplay between fertilizer composition, GHG emissions, soil microbes, and crop yields in agricultural soils are scarce and incomplete give the current knowledge on soil microbial communities
We address the following research questions: (1) How can GHG emissions be reduced through the application of organic amendments without losing crop performance and how is crop growth itself affecting GHG; (2) How does organic fertilizer input influence microbial abundance and composition of microbial guilds involved in the C- and N-cycle, as well as the plant growth–promoting bacteria (PGPB)/PGPF; and what are the key (a)biotic factors controlling and shaping the microbial communities after the addition of organic amendments, and are changes in the microbial communities permanent? We hypothesize that the application of single or mixed organic fertilizers results in a more enriched and balanced microbial community, leading to lower GHG emissions without losing crop performance

Summary

Introduction

Atmospheric concentrations of the major GHG, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), have increased since the industrial revolution by 40%, 150%, and 20%, respectively (Sohngen and Tian 2016; IPCC 2018); approximately 50% and 60%, respectively for CH4 and N2O of these GHG emissions originated from agriculture (Tian et al 2016). Climate-smart sustainable agriculture focuses on minimizing GHG emissions and increasing C sequestration while maintaining or even enhancing crop yield (Paustian et al 2016). There is an urgent demand for fertilizers that release nutrients in a more sustainable way, with lower eutrophication effects, build-up of soil C while still supporting plant growth. In order to support soil functions and maintain or even increase crop yields, combinations of organic and more mineral green fertilizers (like green manure) may bear this potential by providing an accessible fertilizer with long-lasting effects on soil quality (Tahat et al 2020). Systematic studies exploring the interplay between fertilizer composition, GHG emissions, soil microbes, and crop yields in agricultural soils are scarce and incomplete give the current knowledge on soil microbial communities

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Conclusion