Soils low in phosphate need phosphorus applications, as trials with oranges and lemons in Brazil show. Phosphate uptake occurs throughout the growth period, after flowering and through late fruit maturity. Good availability is important during periods of active root growth e.g. springtime and in between vegetative flushes.
Work on satsumas in Turkey shows that rates of 0.57lb P2O5/tree provided optimum yields over a four year period. For mature trees, application timing is not critical. Fertilizer is usually applied at the beginning or the end of season. Regular application by fertigation can increase efficiency of P-uptake and ensure good utilization of other nutrients at the same time.
Phosphorus has a positive effect on juice content of the fruit.
Over supply of phosphorus can reduce peel thickness, as study with mandarins in India shows. Therefore it is important to maintain the right balance between N and P rates.
|Phosphorus at citrus growth stages|
|Flowering||Maintain long-term productivity|
|Post Harvest||Maintain long-term tree productivity|