THE CONTRIBUTION OF ROOTS AND RESERVES TO TREE NUTRIENT DEMANDS: IMPLICATION FOR THE INTERPRETATION OF ANALYTICAL DATA

Roots are the organs of nutrient uptake thus knowledge about root length, turnover, and distribution is required to determine the trees potential to aquire nutrients.
Reliable methods to assess root length and turnover at different times of the year are needed.

The contribution of a reuse of nutrient reserves from different perennial parts of the tree has to be considered.
Therefore information about the temporal availability of reserves and about their refilling are needed.
Growth and development of the different organs of trees and their nutrient metabolism should be investigated to determine budgets and to enable predictions about rates and times of external nutrient applications.

Factors such as root length and distribution, soil properties, and changes in nutrient (i.e. nitrogen) content and distribution in the soil at different times of the year have to be considered in soil sampling and in interpretation of soil analysis data.

Leaf analysis data should only be used in conjunction with other information when making predictions about orchard nutrient requirements.