Orchard fertilizer: fruit trees, olive trees and citrus

Our amendments and organo-mineral fertilizers are built on Mazor®, the result of seven months of controlled composting with the patented Cronops® process. Plant oilseed cakes, grape and olive pulp, coffee grounds and, depending on the formula, sterilized animal materials are transformed: carbon is stabilized, the C/N ratio falls, pathogens are eliminated and the microflora develops. That is what sets a composted material apart from the same material in its raw state.

Patented Cronops® process · FR2103847

An orchard removes few mineral nutrients compared with an annual crop. Per tonne of fruit harvested, allow 1.2 to 1.6 kg of nitrogen for apples, 3 to 4 kg for apricots and 4 to 5.3 kg for cherries. Potash removal is higher: 2 to 2.5 kg of K₂O per tonne of apples, 5 to 6 kg per tonne of apricots. Potash drives fruit size, colour and firmness.

Meanwhile, the soil loses 1 to 2 tonnes of humus per hectare every year through mineralization. Without regular inputs of organic matter, soil structure deteriorates, water infiltration declines and roots explore a smaller volume of soil. Fertilizer alone does not make up for this loss.

That is why our programme always follows the same order: soil support, nutrition, adjustments.

Olive trees need nitrogen from late winter until fruit set in late May or early June. Organic nitrogen fertilizers are applied in late February or early March; in irrigated groves, a second application can be made in summer. Potash reserves are built up from autumn onwards for the next crop.

Requirements depend on yield. For 2 to 3 tonnes of olives per hectare, a typical rain-fed yield, allow 30 to 50 kg of nitrogen, 15 to 25 kg of phosphorus, 50 to 60 kg of potash and 15 kg of MgO per hectare per year. For 5 to 6 tonnes, allow 70 to 90 kg of nitrogen and 80 to 100 kg of potash.

For olive grove maintenance, we recommend a balanced organo-mineral fertilizer with magnesium and sulphur, such as AB’Flor® 7-5-7 S + 2 MgO SE, preceded by an organic amendment if the soil is poor. For a potted or garden olive tree, our Fruitier Marcel le Jardinier fertilizer is formulated for home gardeners.

Clementine, orange and lemon trees need more nitrogen and potash than olive trees, in split applications from late winter to early summer. Magnesium matters too, as excess potash hinders its uptake. We ship citrus fertilizer to Corsica from September (AB’Flor® 13 N, for example): this autumn application prepares the trees for the next flowering.

On calcareous soil, citrus trees are prone to iron chlorosis. An organo-mineral fertilizer enriched with iron, such as Mikroflor Germifer® 3-2-2 + Fe, prevents the deficiency. Concentrated organic nitrogen, such as AB’Flor® 13 N, revives a tree that lacks vigour.

Everything is decided before the trees go in. A base organic amendment (3 to 5 t/ha for our Humiflor® amendments) improves the structure of the soil the roots will colonize. In the planting hole, Germiplant®, our planting mix, helps the tree establish at 1 to 2 kg per tree.

Next come phosphorus for root development, with AB’Flor® 8-10-2 S, and nitrogen in split applications. In the first year, limit a young orchard to 40 to 60 kg of nitrogen per hectare depending on vigour, applied in doses of 15 to 30 kg.