Use of Differences in Natural Abundance of 15 N for the Assessment of Nitrogen Fixation

Abstract

In nature, most soils have slightly higher 15N abundance than the atmosphere. This difference in natural 15N abundance between soil and atmospheric N2, known as delta 15N, or N, has been used in the assessment of nitrogen fixation in plants. N2 - fixing plants, when grown together with non N2 - fixing plants, when grown together with non N2 - fixing plants, have been found to have a lower 15N enrichment than the latter which receive 15N solely from the soil. Based the difference in natural 15N abundance, the 15N has recently been used to assess nitrogen fixation. This technique is also economical, as 15n - labelled fertilizer is not needed.