Articles
SOME EFFECTS OF ORCHARD SOIL MANAGEMENT ON THE MINERAL NUTRITION OF APPLE TREES
Greenham (1976) showed that 24 years of fertilizer applications increased the nitrogen content of apple leaves by only 0.15 per cent relative to an unfertilized control whilst within two years a grass sward caused a reduction of 0.45 per cent.
Gras and Trocmé (1977) also concluded that soil management effects were greater than those of nitrogen, phosphorus and potassium fertilizers.
Grass competes with the trees for nitrogen whereas cultivation damages tree roots in the surface soil horizons (Coker, 1959) and so reduces the uptake of phosphorus and potassium which are particularly plentiful there.
In Western Europe most recently-planted trees are grown in weed-free, herbicide-treated, strips of bare soil separated by grassed alleys.
In this situation the reduced competition from grass and absence of root disturbance should give greater access to nutrients in the richer surface soil.
Recent reviews of the effects of soil management on nutrition have tended to be dominated by comparisons of grass and cultivation (Greenham, 1976; White and Greenham, 1967). Although a number of recent papers (Gormley, Robinson and O’Kennedy, 1973; Robinson, 1974; Stott, 1976; Atkinson and White, 1976a) have reported some effects on nutrition as a result of herbicide-based management, the subject has not been comprehensively reviewed.
This paper discusses some of the effects of this type of management, especially in experiments carried out at East Malling.