Phosphorus transport from diffuse agricultural sources : shallow subsurface pathways in grassland soils.

Dils, R. M. and Heathwaite, A. Louise (1999) Phosphorus transport from diffuse agricultural sources : shallow subsurface pathways in grassland soils. In: Impact of land-use change on nutrient loads from diffuse sources :. IAHS Publications, Wallingford, pp. 57-64. ISBN 1901502953

Abstract

Phosphorus (P) can be transferred from grassland soils along a number of surface and subsurface hydrological pathways. Currently, our understanding of subsurface transport mechanisms for P is limited. This research examines P transport in shallow subsurface pathways (matrix and macropore flow) under controlled laboratory conditions, and under true field conditions. Simulated rainfall experiments were performed on triplicate soil cores (0.01 m3) extracted in summer and winter from an intensively managed grazed grassland field. Matrix and macropore flow samples were collected in situ in this field. Despite the differences in sampling approach, the forms and amounts of P transported in matrix and macropore flow exhibited distinct similarities. In summer matrix flow, for example, total P (TP) concentrations rang ed from 47-185 ug l" 1 in the field and from 76-163 ug l" 1 in leachate from cores, with soluble P constituting 65% and 6 1% of TP, respectively. These findings further current understanding of field-scale P transport processes.