Arbuscular mycorrhizal fungal species differ in their effect on nutrient leaching

Abstract

Arbuscular mycorrhizal (AM) fungi have been shown to play a crucial role in nutrient cycling and can reduce nutrient losses after rain induced leaching events. It is still unclear whether nutrient leaching losses vary depending on the AM fungal taxa that are present in soil. Using experimental microcosms with one of two different host plants (the grass Lolium multiflorum, or the legume Trifolium pratense) and inoculated with one of three different AM fungal species (Claroideoglomus claroideum, Rhizoglomus irregulare, and Funneliformis mosseae), we tested whether AM fungal species vary in their effects on nutrient leaching and plant productivity. AM fungi reduced nitrogen leaching, and the effects varied depending on host plant species and the identity of the AM fungal species present in soil. The reduction of nitrogen leaching losses was strongest in microcosms planted with Trifolium. The effects of AM fungi on phosphorus leaching losses were relatively small, and in most cases not significant, although a significant negative correlation between root colonization and phosphate leaching was observed in microcosms planted with Lolium. AM fungi enhanced plant P uptake for both plant species, and different AM fungi varied in their effects on plant biomass and nutrient acquisition. Our results demonstrate, for the first time, that AM fungal species differ in their effect on nutrient leaching. This indicates that agricultural practices that alter AM fungal communities also indirectly change nutrient cycling and nutrient leaching losses.