Dissolved organic carbon and nitrogen leaching through a volcanic vadose zone

Abstract

The quantities and fate of dissolved organic carbon and organic nitrogen leached over two years from the bottom of the root zone of a low quality pasture and through to the groundwater are discussed. The modern soil at this Lake Taupo catchment site belongs to the Oruanui loamy sand series within the Podzolic Orthic Pumice Soil subgroup, with an underlying vadose zone of gritty coarse sands and pumice fragments, with groundwater at approximately 5.5 m depth. The stocking rate was approximately 8 stock units per hectare, with an accompanying maintenance fertilizer regime of 17 kg phosphorus and 30 kg sulphur per hectare applied to the pasture in autumn.