Nutritional elements Calcium: Generalities
Calcium is the natural component of most of the original materials of soils, present in many soils in the form of carbonate, phosphate, silicate and in organic matter. In the soil it combines with other nutrients reducing the solubility of both. From a strictly physiological point of view, calcium is an element of nutrition; as an essential component of protopectins present in the cell walls it is directly responsible for the consistency of the fruits. The calcium intake increases the mechanical resistance of the tissues in the vegetables due to the action of support and reinforcement; in particular it prolongs the maturation times and the senescence of the fruits, keeping the structure of the walls and cell membranes intact. The main functions of the element in plants are to improve the general vigor of the plant and the hardness of the stems, influence the assimilation of other nutrients, neutralize some toxic substances that are produced in the plant, increase the content of calcium in the crops intended for supply.
The main causes that determine the lack of calcium are:
· Insufficient equipment of the element in the ground
· Unavailability due to Ph acids
· Excessive content of sulfur or phosphorus which bind calcium forming insoluble compounds
· Antagonism with NH4 +, K +, Mg ++ ions (avoid fertilization with potassium, magnesium and ammoniacal nitrogen in bloom and for a month later).
The deficiencies manifest themselves on young leaves and terminal buds that appear curved and distorted and then die starting from the tips and along the margins, the leaves are wrinkled and in some cases the young leaves do not open, the roots are short and very grouped .
In ornamental plants the Calcium is very important because it participates in the formation of the cell wall, its deficiency determines an insufficient "bones" of the plants with deformed buds and short-lived flowers.
In fruit-growing, any problems with this element (pitting, internal disintegration of the apples, lenticellosis, vitrescence, apical drying of the rachis in some vines, tip burn of the lettuce, edging of the poinsettia, etc.) are found on unbalanced plants, equipped with excessive vigor and low production.
An excess of Calcium results in a lower absorption of potassium, Magnesium and ammonium ion, soils too rich in Calcium can also induce problems linked to the availability of many microelements, in particular iron and boron, due to a high soil alkalinity. No less important is the role of calcium as a regulator of soil reaction, the deficiencies of this element coincide with the acidification of the soil and its effects on the nutritional availability of other elements.
Plants are not always able to find all the calcium they really need in the substrate because Calcium moves very slowly in the soil and is assimilated only by roots in good condition, young and growing, so it is not always able to be transferred to the soil. organs that require an adequate quantity, the best way for plants to absorb calcium is through foliar fertilizations.
Calcium (chemical symbol Ca) is reported in the composition of fertilizers such as calcium oxide (CaO).