Foliar diagnostics is used to detect nutrient deficiencies or oversupply. The leaves are usually the suitable parts of the plant because they correspond to places of active growth.
For the olive there are two sampling periods: in winter, where leaves with a stem are collected from the middle of the last vegetation (aged 5-8 months) and in July, leaves with a stem from the middle of the main vegetation
Sampling is done with the rule of the square root, ex. from 400 trees a sample is taken from 20 trees around the trees and the trees must cover the whole olive grove.
The leaves are collected in plastic bags in sufficient numbers (100-150 sheets) and sent for analysis immediately or stored for one - two days at most at room temperature.
Table1: Nutrient adequacy limits for winter sampling of olive leaves (by dry weight)
|
Nutrient |
Adequacy limits (min-max) |
|
|
Nitrogen Ν (%) |
1,5 |
2,5 |
|
Phosphorus Ρ(%) |
0,09 |
0,3 |
|
Potassium Κ (%) |
0,7 |
1,2 |
|
Calcium Ca (%) |
1,0 |
2,5 |
|
Magnesium Μg (%) |
0,1 |
0,3 |
|
Sulfur S(%) |
0,1 |
0,25 |
|
Manganese Mn (mg/kg) |
25 |
150 |
|
Zinc Zn (mg/kg) |
10 |
50 |
|
Boron B (mg/kg) |
20 |
75 |
|
Copper Cu (mg/kg) |
5 |
20 |
|
Iron Fe (mg/kg) |
50 |
150 |
|
Molybdenum (mg/kg) |
0,03 |
|
|
Sodium Na (%) |
-- |
0,2 |
|
Chlorine Cl (%) |
-- |
0,5 |
Olives have significant needs for nitrogen, potassium, and boron.
Nitrogen is an essential ingredient for the olive and especially in the period March - June where its availability is necessary for the development of flowering buds in olives and the season when the stone hardens (July-August).
Nitrogen deficiency leads to reduced fruiting or parenchyma (the condition where olives bear fruit every two years or even less). If the tree does not have the required nitrogen during the spring, the flowers are barren, and the olive is heavily fruitful.
Phosphorus requirements are low and mainly in cases where phosphorus fertilizers have not been used for several years and the olive grove is in soils with low pH or high calcium carbonate concentration.
If phosphorus is present in the leaves in winter at a concentration greater than 0.1% and N / P <20 is valid then no phosphorus addition is required. Otherwise, P units are added in a ratio of N: P 3-5: 1, depending on the results of the leaf diagnostics. For maintenance purposes, a quantity of phosphorus may be added every two years. Of course, young trees need phosphorus fertilization to grow.
Phosphorus malnutrition appears as dotted leaf chlorination, but it is not easy to render phosphorus malnutrition just because of the symptoms.
Potassium is a basic nutrient with a large outflow, as a large amount of potassium is removed from the olive fruit during pruning. During the ripening period of the fruit, 60% of the potassium is concentrated in it.
For olive groves that did not have the required lubrication care, the amount of potassium can be twice that of nitrogen, while where there is a crop care potassium and nitrogen can be added in equal amounts.
Potassium deficiency is manifested by the change of color at the top of the plate to brown-copper, with parallel drying of the upper part of the leaves by 1/3 of their length. Microfiber and drying of new branches are also observed.
Boron participates in the better adsorption and movement of other minerals and therefore helps significantly in the growth and productivity of the olive tree.
The lack of boron is manifested by chlorination of the extreme part (approximately 1/3 - 2/3 of the leaf) and the coloring of green-yellow to yellow / orange of the leaves.
In case of severe deficiency, micro-leafing, change of leaf shape and intense leaf fall are observed. Trees with a boron content of less than 7mg / kg do not form flowering buds.
Calcium deficiency is manifested by chlorination of the upper part of the leaves and parallel whitening of the nerves in chlorination.
Magnesium deficiency is manifested by chlorination of the leaves from the top or sides and then spreads throughout the leaf. In exacerbation of the deficiency there is deciduous and poor vegetation.
Olives are grown in soils that are neither too cohesive nor too light to retain moisture from rain and make better use of the roots. In very fertile and moist soils, vegetation is greatly favored at the expense of normal fruiting and the roots rot. In wet soils in the lowlands the fruit becomes watery and contains less oil, which is thick, dark in color and rather poor quality. The olive prefers calcareous and potassium-rich soils. Olives grown in moist saturated soils are more vulnerable to weather changes and disease. soil, such as pesticides and verticillium wilt.
Consult HELLASCHEM for:
-
Olive mill and / or olive oil standardization unit certification