Measuring and monitoring nitrogen and phosphorus flows and losses in grassland systems.

Methods of investigating nitrogen and phosphorus cycling in grasslands are reviewed with reference to the increasing emphasis on the environmental consequences of losses of N and P. Topics discussed include the measurement of biological nitrogen fixation, N and P in manures, mineralization and immobilization of soil N and P, P precipitation/dissolution and sorption/desorption processes, soil N and P pools, and losses and emissions. The role of models is briefly considered.