Soil nitrogen studies with particular reference to fruit-tree nutrition : being a thesis submitted in partial fulfilment of the requirements for the degree of Master of Agricultural Science (Hort.) of the University of New Zealand

The importance of nitrogen for the nutrition of fruit trees is well established and it is largely for this reason that much attention has been given by overseas workers to factors influencing the level of soil mineral nitrogen. Soil managment methods have been shown to exert a considerable infleunce on mineral nitrogen level of the soil, those methods which make nitrogen available most readily depleting the total supply in the soil most rapidly. In view of the importance attached by overseas workers to the influence of soil managment practices on the level of the soil mineral nitrogen, and as no previous study of this problem appeared to have made in New Zealand, the present investigation was undertaken. A study was made to compare the effects of clean-cultivation and sod-culture on both the mineral level and pH in a silt-loam orchard soil over a period of several months. This afforded an opportunity to investigate also the effect of seasonal factors on the periodic variations in mineral nitrogen under both systems of management. [From Introduction