Arbuscular mycorrhizal fungi community linkages to soil nutrient availability across contrasting agroecosystems

Abstract

Perennial grain crops have been proposed as a groundbreaking tactic to establish sustainable agroecosystems, as their growth habit and no-till management likely invoke multifunctionality such as improvement of soil structure as well as increases in nutrient retention and carbon (C) sequestration. Arbuscular mycorrhizal fungi (AMF) are multifunctional symbioses, which are ecologically important for over 80% terrestrial plants that form root associations with these fungi. Our study examined AMF diversity and community composition in annual and perennial grain crops; with and without nitrogen (N) fertilizer addition at two field sites within the Canadian prairies (Breton and Edmonton). AMF diversity and community composition were significantly different between the two study sites. This was attributed to the contrasting cropping management histories of the sites; previous long-term land use in Edmonton was annual cropping, whereas Breton was perennial forage crop. AMF community composition was not different between annual versus perennial grain cropping on both the bulk soil and rhizosphere (roots). Overall, the addition of N fertilizer did not change AMF diversity and community compositions but increased the abundance of Archaeospora. The most predominant genus in these temperate agroecosystems was Paraglomus, while Archaeospora and Claroideoglomus were observed in the roots compartment but unfrequently and specifically at the Edmonton site. Interestingly, Archaeospora and Paraglomus were significantly correlated with changes in particulate organic matter C, while Claroideoglomus had a positive correlation with ammonium concentration. Results revealed functional associations between key soil properties and certain AMF genera, which showed to be site specific.