Does variable rate irrigation decrease nutrient leaching losses from grazed dairy farming?

A six-year study was conducted to determine whether the use of variable rate irrigation (VRI), compared to uniform rate irrigation (URI), could decrease N and P leaching losses from a 143ha area under intensively grazed dairy cattle that had been partly hydrologically isolated by the installation of artificial drainage pipes. After accounting for potential differences in flow, annual load estimates of N and P species at the downstream site under VRI were about 80–85% less than that lost under URI. Wider adoption of VRI technology could therefore decrease farm leaching losses and nutrient concentrations in receiving waterbodies.