HortResearch Publication - Citrus Fertiliser Recommendations Fertiliser Recommendations for Horticultural Crops Citrus Minimal pruning is generally carried out on citrus grown in New Zealand, thus the quantity of nutrient which needs to come from soil reserves or fertiliser applications in a cropping orchard, depends on that removed in harvested fruit.
Most citrus grown in New Zealand has a tendency to biennial bearing.
During an off year the amount of fertiliser applied should be reduced. In cases of extreme biennial bearing with almost no crop in the off year, as is often the case with Wheeny grapefruit, fertiliser could be eliminated altogether, provided that there were no obvious nutritional disorders apparent. The youngest mature leaves on non-fruiting terminals should be selected with each sample consisting of at least 24 leaves taken at random from trees throughout the block. Interpretive standards for nutrient concentrations in the leaves are listed in Table 1. Critical concentrations for foliar analysis of citrus.