The nutrient supply to the fruit tree depends on inherent availability in the soil, modified by various factors, of which the soil management system may be more important than the application of fertilisers.
Evidence is considered from quantitative nutrient uptake studies, and an outline is given of the nature of the effects of nutrient supply on the fruit tree.
In reviewing field experiments involving the application of fertilisers to fruit trees, attention is concentrated on trials carried out in England in recent years.
The official system of fertiliser recommendations for P, K and Mg is based on routine soil analysis. Leaf analysis can be used to modify the fertiliser programme, and a table of suggested satisfactory ranges of leaf concentration is to be included in the official recommendations.
Nitrogen recommendations, which are higher in areas where the normal summer rainfall is low, depend on the soil management system, but it is necessary to take into account the nitrogen status of the tree as indicated by its performance and appearance and (if available) leaf analysis.
Leaf analysis surveys indicate that average rates of fertiliser application in orchards could be reduced with potential advantages in fruit quality as well as in economy.