Nitrogen isotope ratios in surface and sub-surface horizons of new zealand improved grassland soils

Abstract

Nitrogen isotope analysis of 61 soil samples (0–7.5 cm) from New Zealand improved grasslands showed a variation in15N concentration with respect to air of -1.1 to +6.8 parts per thousand (815N), with a mean of +3.2.815N values were found to increase with depth from the soil surface in Wharekohe silt loam and Waimate North clay loam. The 815N values were not well correlated with a number of soil characteristics including total soil N and nitrification activity. The variation of 815N with depth further complicates the use of natural15N as a tracer in agricultural research. © 1981 Taylor & Francis Group, LLC.