Citrus fruits

Home Fertilization Guide Citrus fruits

Citrus trees need fertile, loamy soils of medium mechanical composition, neither compact nor calcareous, but slightly acidic (optimum pH = 6), water permeable and with good drainage, in order to provide satisfactory production in terms of quantity and quality.

They thrive in mild, coastal climates and have little resistance to cold. The most resistant is the orange tree, followed by the mandarin tree and lastly the lemon tree. As a general principle, the N:P2O5:K20 ratio (1:0.3:1) is followed in the fertilization of adult, fully productive citrus trees.

In practice, the quantities of nitrogen, potassium, magnesium and other nutrients that need to be added through fertilizers to replenish the lost elements at the citrus orchard, do not only concern the losses through the harvesting of the fruits, but also the quantities removed through pruning, strongly bound to the soil and lost through evaporation or/and leaching, etc.

The nitrogen needs of citrus trees are increased from February to April. During this period the trees need 40% to 50% of the nitrogen they require annually in any case, no later than bud swelling. The remaining nitrogen is applied in equal amounts during the fruit setting, fruit development and autumn germination stage.

The phosphorus requirements of citrus trees are generally low. Usually 0.25-0.3 kg per stremma are needed during the period when the renewal of the root system of the trees, the development of buds, flowering and fruit setting occur.

Potassium is essential in the cultivation of citrus fruits. It increases resistance to water stress and cold, corrects the negative effects of excessive nitrogen fertilization, increases fruit size, improves flesh structure, increases vitamin C content and finally increases yields. On the contrary, too much potassium causes thickening of the peel leaving it greenish, reducing the juice content and increasing the acidity of the juice. It also causes a reduction in magnesium uptake, which is an absolutely essential element for the quality production of fruits. An application of 0.2-0.5 kg per stremma of potassium is considered satisfactory.

Deficiencies of trace elements such as zinc, iron, boron and manganese should not be considered negligible.