Arbuscular mycorrhizal fungi influence decomposition of, but not plant nutrient capture from, glycine patches in soil

The contribution of different arbuscular mycorrhizal fungi (AMF) to nutrient capture from an organic patch, and the subsequent impact on root proliferation was investigated. Organic patches were created with glycine labelled with N-15 and C-13. This allowed decomposition (as (CO2)-C-13 release) and uptake of nutrients (as C-13 and N-15 enrichments in the plant tissues) to be followed. Changes in root responses were followed in situ by the use of minirhizotrons and compared to responses in control (H2O) patches. Although there were differences in internal colonization and external mycelium production among the three AMF tested,. none of the fungi responded to the presence of the glycine patch, and N and C capture was no different to uncolonized controls. However, the presence of glycine affected the manner in which colonized roots responded, particularly below the patch. The presence of AMF affected the decomposition of glycine. Root responses to the presence of N-rich patches appear more important than AMF responses.