Microbial biomass phosphorus contributions to phosphorus solubility in riparian vegetated buffer strip soils

This study tests the hypothesis that microbial biomass phosphorus (P) makes a significant contribution to P solubility in riparian buffer strip soils. In 36 soils collected from buffer strips within three UK soil associations, water-extractable inorganic P solubility was most strongly related to NaHCO3 extractable inorganic P. However, within individual soil associations where soil pedological properties and management were similar, water-extractable inorganic P was most strongly related to microbial biomass P. These results highlight the difficulty in predicting dissolved P leaching risk based on agronomic soil P tests alone and the dissolved P leaching risk presented by having soils high in organic matter and microbial biomass P in close proximity to surface waters.