Long-term agricultural management impacts arbuscular mycorrhizal fungi more than short-term experimental drought

Dominika Kundel,Andreas Fliessbach,Dag Ahrén,Klaus Birkhofer,Sandeep K Kushwaha,Katja Kozjek,Katarina Hedlund,Pål Axel Olsson

doi:10.1016/j.apsoil.2021.104140

Abstract

Agricultural management practices and extreme weather events associated with climate change can influence the diversity and abundance of arbuscular mycorrhizal fungi (AMF) with potential consequences for crop production. However, the importance of the interactive effects of long-term agricultural management and extreme weather events on AMF communities in agricultural soils is not yet fully explored. A short-term drought experiment with rainout-shelters was performed in winter wheat fields in a long-term agricultural trial with organic (biodynamic) and conventional management practices. During four months of the winter wheat growing period (March–June 2017), the rainout-shelters reduced the ambient precipitation by 65% on average. At two sampling dates, the AMF diversity and community composition were assessed using a single-molecule real-time (SMRT) DNA sequencing. A total of 955 amplicon sequence variants (ASVs), belonging to twelve genera were identified. The long-term farming systems and the short-term experimental drought did not affect AMF ASV diversity levels. The AMF community composition at the genus level differed between the organic and the conventional farming systems, but no distinctive communities were found in response to the experimental drought. The three most abundant genera Acaulospora, Paraglomus and Funneliformis were correlated to the two farming practices. Our study demonstrates that AMF communities in agricultural soils are responsive to long-term farming systems, and are resistant to one short-term summer drought event.

Highlights

Climate change and agricultural intensification are currently considered as the major threats to agricultural ecosystems that may cause losses in soil biodiversity (de Graaff et al, 2019; Geisen et al, 2019)
We addressed the following questions: (I) How do long-term organic and conventional farming practices and a short-term experi mental drought and their interactive effects influence the diversity and community composition of arbuscular mycorrhizal fungi (AMF)? (II) Which AMF taxa are sensitive to drought and most abundant in a specific farming system? (III) What are the key soil properties influencing the AMF community composition and would SOC content mitigate drought effects?
Our results show that despite an ambient precipitation reduction of 65% across the winter wheat growing season produced by the drought treatment, the achieved reduction in soil moisture was not enough to cause drought effects on the AMF community composition

Summary

Introduction

Climate change and agricultural intensification are currently considered as the major threats to agricultural ecosystems that may cause losses in soil biodiversity (de Graaff et al, 2019; Geisen et al, 2019). Climate models for Central and Southern Europe predict an increased number of extreme weather events, resulting in more frequent and extended drought pe riods, as well as rainfall extremes (Iglesias and Garrote, 2015; Spinoni et al, 2015a). These changes are expected to have a negative impact on agricultural production in Europe (Webber et al, 2018) and the di versity, abundance and functions of soil microorganisms (Cavicchioli et al, 2019; Jansson and Hofmockel, 2020). It is crucial to understand whether existing agricultural practices can be adapted to future extreme weather events in order to make agricultural ecosystems more resilient (Gornall et al, 2010; Spinoni et al, 2015b)

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