Nutrient addition increases biomass of soil fungi: evidence from a South African grassland

Theory predicts that nutrient addition to soil reduces the benefit of mycorrhizal associations to plants. This study sought to determine how long-term management of soil fertility influences the abundance of fungal mycelium. Ingrowth mesh bags were used to measure mycelial biomass in grassland plots fertilised (nitrogen [N] and phosphorus [P]) and limed for 60 years. Mycelial biomass more than tripled with N addition, whereas P addition showed modest increases in biomass. Applied in combination, N and P fertilisers had no effect on mycelial biomass. Liming alone had no effect but increased biomass when it was applied in combination with N. The results of this study suggest that the fertiliser affected the biomass of the fungal community, and may also change the composition of the fungal community.