Soybean growth and foliar phosphorus concentration mediated by arbuscular mycorrhizal fungi from soils under different no-till cropping systems

Soil use and management modify mycorrhizal interactions, but how these changes affect the growth and nutrition of crops under different contexts has been poorly studied. The objective of this study was to evaluate the effects of arbuscular mycorrhizal fungal (AMF) spore communities belonging to two no-till cropping systems (soybean monoculture and soybean-maize rotation), and uncultivated grasslands replicated at four locations along a regional geographic gradient on soybean mycorrhizal colonization and performance. At a regional scale, AMF spore richness was higher in uncultivated grasslands, intermediate in crop rotations, and lower in monocultures. Arbuscular mycorrhizal colonization in soybean roots was also higher in uncultivated soils but did not differ between no-tillage systems. Soybean growth was positively affected by AMF from uncultivated grasslands in comparison to control without AMF. Instead, there were no significant effects of AMF from no-till cropping systems. Foliar P concentration was lower in monocultures irrespective of AMF. At the local scale, patterns were highly variable and differed between locations. These results highlight the importance of scales for management decisions in agriculture and add further support for the context-dependent nature of mycorrhizal interactions.