Direct field measurements of leaching losses of nitrogen in pasture and cropping soils using tension lysimeters

A method for direct field measurement of leaching losses of soil nitrogen is described.Tension lysimeter plates are inserted in the soil profile with minimum disturbance of the soil above the plates.The method was used to measure leaching losses of nitrogen in soils under pasture, fallow, and wheat.Leaching losses were highest under pasture, followed by fallow and wheat.However, the volumes of leachates collected were very variable mainly because of the non-uniformity of the soil profile at different depths, particularly the variable layering and sand lenses in subsoils which cause lateral flow and variable applied tensions.These limitations are discussed together with suggested improvements of the technique.