Nitrogen and phosphorus in streamwaters from adjacent pasture, pine, and native forest catchments

Abstract

Measurements were made of nitrogen (N) and phosphorus (P) concentrations in streams draining three adjacent catchments of different land use. Generally, the pasture catchment stream showed highest concentrations of N and P, compared to the streams draining the pine and native catchments. Total N export coefficients (kg km^‐2 year^‐1) were estimated as 1195, 131, and 367 for the pasture, pine, and native catchments, respectively. Total P export coefficients (kg km^‐2 year^‐1) were estimated as 167, 9.5, and 12.0 for the pasture, pine, and native catchments, respectively. Exports of N and P from the pasture catchment were unevenly distributed through the year, with most export occurring as particulate forms during storm events. By comparison, export from the two forested catchments was more evenly distributed and baseflow dissolved forms of N and P formed a higher proportion of total export. The influences of land use were attributable to differences in hydrology, source materials of N and P available for transport, and rates of upstream processing.

Key words:

• nitrogen
• phosphorus
• water quality
• land use
• streamwaters

Notes

now: Department of Scientific and Industrial Research