Vol. 44 No: 2

Title:
The Effects of Mineral Fertilizer on Seasonal Changes in the Amount of White Root on Apple Trees in Grass

Author:
G.C. HEAD

pp: 183-188

Abstract:
Measurements in an underground observation laboratory showed that, in 3 years, only small quantities of white root were present in the spring on nitrogen-deficient apple trees growing in grass. N K fertilizer applied in the spring greatly increased the amount of white root within a few weeks. Fertilizer application resulted in no lasting increase in nitrate or ammonium nitrogen in the soil and only a small increase in leaf nitrogen content in one year. It is thus not certain whether the observed effects were due to incipient nitrogen deficiency in the trees, and its correction, or to a direct effect on the root of an alteration in the levels of nitrogen, potassium, or of an unknown biological component in the soil.

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