Soil parameters and plant responses associated with arbuscular mycorrhizas from contrasting grassland management regimes

Abstract

Increased interest in sustainable low-input forms of agriculture has focused attention on the role of beneficial soil micro-symbionts, such as arbuscular mycorrhizal fungi (AMF), in plant productivity and health. Root colonisation by AMF and AMF spore density was significantly lower in grassland soils with a history of high-input, conventional management than in soils with a low-input or organic management. Spores of AMF isolated from contrasting management regimes, taken from a total of 24 sites at 13 farms, were used in a series of inoculation trials involving three host plants ( Allium ameloprasum L., Trifolium repens L. and Lolium perenne L.). The mean yield response (measured as shoot dry weight) was significantly greater when host plants were inoculated with spores taken from farms with organic rather than high-input management for both Allium and Trifolium hosts. Very low levels of root infection in Lolium hosts excluded these plants from further analysis. Not all organic farms had highly effective AMF associations however, and some highly effective AMF isolates were found in high-input systems.