Relationships between forms of nitrogen and hydrological characteristics in a small stream near Adelaide, South Australia.

Abstract

Concentrations of various forms of nitrogen in a stream which drains a small and mostly agricultural catchment near Adelaide, South Australia, were investigated and related to stream hydrological characteristics. During baseflow, nitrate-nitrogen was the major component of total nitrogen but in stormflows reduced forms of nitrogen predominated, largely in a suspended state. There were some trends in concentrations according to rates of flow, and empirical relationships were discerned between nitrogen concentrations, load, and discharge values. Using these, an annual total nitrogen load of 9.9 tonnes (for 1976/1977) was calculated, a value equivalent to an average yield of 24.2 kg ha^-1 year^-1 of total nitrogen. Loadings for reduced nitrogen (measured as total kjeldahl nitrogen) and nitrate-nitrogen were 7.8 and 16.4 kg ha^-1 year^-1 respectively.