VII. Recent alluvium, Palmerston North

Abstract
A dry warm year and a cool moist year resulted in 184 and 232 kg N fixed/ha annum respectively. Between year, and between season within year, variation in N fixation was explained by variation in clover growth and soil N available to the clover. The depth profile of N fixation varied from 90 to 10% in the top 75 mm of soil in response to soil moisture changes.