Movement and loss of nitrate following heavy applications of sewage sludge to a poorly drained soil.

Abstract

Very high nitrate concentrations were found near the soil surface for several years. Downward movement of nitrate was very slow. There was a continuous loss of nitrate over the study period, attributed to denitrification. The denitrification intensity of the soil profile decreased with depth, but was still appreciable at the greatest depth. When oxygen diffusion in the soil was slow and oxygen demand was high, denitrification occurred within a few centimetres of the soil surface or an air-filled pore. Poorly drained soils promote denitrification and offer some protection against the risk of nitrate pollution of groundwater. -from Authors