Olive Oil School of Spain

Olive Tree Nutrition: Boron, Zinc and Iron

Written by Escuela Superior del Aceite de Oliva | 29/10/19 10:03

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¿Do you know these three elements that influence in the olive tree nutrition?

Boron

Boron is a very important nutrient in olive groves. It is involved in hormonal processes of growth, and in the exportation of sugars from source structures to structures that consume the sugar. For plants, low levels translate into distortions in growth, with short sprouts that have short leaves, which eventually die and form "witch brooms"

It severely affects set fruits, since this nutrient is highly involved in the importation of photoassimilates by the young, growing olives. If the level of boron is low in the plant between the time when the fruit sets and and the pit hardens, many of the unripe fruits fall off and much of the harvest will be lost.

Boron in the soil is very sensitive to leachates, that occur in acidic, course textured soils in very rainy areas. This is the kind of place where the most severe problems with boron are found.

In general, after a large harvest, the olive trees are left with little boron, so it is a good idea to routinely apply boron in the fertilization, to maintain constant, high production.

Using too much boron in the grove is rarely toxic, but if used in excess in fruit setting it can bring on a higher number of smaller fruits followed by a poor crop, so it should be applied keeping in mind both the foliar level, the past crop, and the upcoming crop.

 

Zinc

Physiological processes related to zinc:

  • Length of the shoot, internodal distance and the size of the leaf.
  • Size of the fruits
  • Fat yield.

Olive trees with low levels of zinc typically have short shoots and short leaves, that look like rosettes. Production is thus reduced both for that year and, since a short shoot cannot hold much fruit, it affects the following year, because the nutrients in a short shoot are disturbed by the extractions of the olives in fall

 

Iron

Iron forms part of the chlorophyll molecule, so if it is deficient, is it very easy to see as chlorosis on the leaves, especially new leaves. Iron is not very mobile in the plant, so it is very difficult for it to be exported from the old leaves to the new ones if there is a deficiency, so that is why the symptoms are noticeable above all in the young leaves.

Nutritional problems with iron are found in very limey soils that are poor in iron content. If there is stagnant water on limey soil, this can produce temporary deficiencies in iron. Deficiencies in iron will affect plant growth, and along with this it will affect the harvest of the following year. For its current year, it will affect the crop because the fruits will be smaller and have a smaller fat yield.