Investigating AMF-mediated P transport in arable and grassland field soils collected throughout Europe.

Phosphorus (P) acquisition is key for global food production. Arbuscular mycorrhizal fungi (AMF) help plants acquire P and are an integral part of sustainable agroecosystems. However, it is still poorly understood which factors drive AMF-mediated nutrient transfer to plants in agricultural soils. Here, we collected soils from 150 cereal fields and 60 non-cropped grassland sites across a 3,000 km trans-European gradient. In a greenhouse experiment, we tested the ability of AMF in these soils to forage for the radioisotope 33P from a hyphal compartment. AMF communities in grassland soils were much more efficient to acquire P and transferred 64% more 33P to plants compared to AMF in cropland soils. Fungicide application best explained hyphal P transfer in cropland soils. The use of fungicides and subsequent decline in AMF richness in croplands reduced P uptake by 43%. Our results suggest that land-use intensity and fungicide use are major deterrents to the functioning and natural nutrient uptake capacity of AMF in agroecosystems.