Balanced crop nutrition of all major and micro nutrients is essential to help build a tree structure that can support this fruit load and ensure that the fruit fills to potential as well as meet the market requirements.
Nitrogen and Potassium are the most critical nutrients needed for strong citrus tree growth and crop yields. As much as 2kg/ha of N per day is needed during fruit enlargement and during maturation similar amounts of K should be available.
Calcium nutrition is also important, particularly during the early stages of growth and throughout fruit enlargement. Calcium is the most widely found element in the citrus leaf and multiple applications during the season produce high yielding crops with the highest fruit quality.
Fruit removal figures show that more N and K are removed than any other nutrient. Calcium is the third most utilized nutrient. It is important to replace the level of nutrients taken-off in the fruit and also that removed by pruning. Timing is critical and should follow guidelines laid down in the nutritional program. Typically, between 150-250kg/ha of N and 100-350kg/ha of K is required every year in mature citrus groves.
To maintain yield, supplies of N, K and Ca are needed in large quantities, though this is only a part of a crop nutrition program. You must ensure that P, Mg, S, B, Fe, Mn, Mo and Zn are also not limiting.