DETERMINATION OF FERTILIZER NEEDS OF PLANTS
The effectiveness of fertilization depends on the one hand on the knowledge of the fertilization needs of plants, which we want to cultivate, the other – from the knowledge of the content of minerals in the soil in a form available to plants. The use of fertilizers on soils rich in a given ingredient not only does not increase the yield, but it has the negative effects of an excess of this component, with a simultaneous deficiency of other nutrients. Therefore, determining the right fertilization needs is of great importance, because it avoids the unnecessary use of fertilizers. In methods, determining the needs of plant fertilization, used:
– external appearance of plants (this is a very general orientation, requires good professional preparation and a lot of practice);
– chemical analysis of plant samples, which can be transferred to specialized laboratories (in practice, it is still very rarely available with us);
– chemical analysis of soil samples, which are performed by chemical and agricultural stations.
In plants, the deficiency of nutrients appears most quickly on the leaves in a very characteristic way, so that it is sometimes possible to define, what nutrient is missing in the soil. Thank you, e.g. nitrogen deficiencies inhibit plant growth. Shoots are short and very limp, poorly developed leaves, thin and light green turning into yellow (in extreme cases, they may even fall from trees or shrubs, especially the oldest). The fruits of trees with nitrogen deficiency symptoms are small, they mature earlier and are strongly colored.
Symptoms of phosphorus deficiency in berry trees and shrubs are not common in practice. Similarly on other plants; Apart from the reduction in yields and the storage life of horticultural crops, it is difficult to determine the external symptoms of the lack of this component.
Symptoms of potassium deficiency first appear on the oldest leaves at the base of the shoots. They are characterized by kidney disease, that is, leaf blade dieback on the periphery. Trees and shrubs bear fruit very poorly, and the fruit is small, in currants ripen unevenly. As for vegetables, they react most to potassium deficiency (especially a reduction in yields): cabbage, cauliflower, cucumber, carrot, celery, rhubarb, beans.
The lack of magnesium causes the inhibition of chlorophyll production in the leaves, which causes the appearance of pale chlorosis on the oldest leaves between the veins, large stains. The tissue at the site of the stains dies quickly, proving the kidney. Infected leaves easily fall off fruit trees and shrubs. If the deficiencies are significant, such symptoms are noticeable already in July, and on the shoots – at the end of summer - only a few leaves remain on the tops. Tree shoots are thinner, they freeze more easily in winter. Young buds on such trees fall more often and the yields are lower.
Boron deficiencies in fruit plants are noticeable primarily on the roots. Their growth and the formation of lateral roots are strongly inhibited. On the above-ground part, deformation of anthers and whole flowers occurs. The most typical symptom of this deficiency is subcutaneous corking of apple and pear fruit flesh, deforming the fruit and visible, after cutting them, stains (similar to spots caused by a disease called bitter spot under the skin) and corky cracks and green spots. Of the vegetables, they are particularly sensitive to boron deficiency: tomato, cauliflower, celery, beetroot and swede. Cauliflower and swede then start to get brown spots, celery and beetroot – rot (visible black or brown spots), In the case of tomatoes, the top clusters fall off and only small fruits develop.
Zinc deficiencies are very rare. A typical symptom of a deficiency of this micronutrient in fruit plants is the inhibition of shoot growth and mosaic-like nephroses on abnormally narrow, rosette-shaped leaves. The tops of such trees may die, fruiting is weak. Apple trees suffer from zinc deficiency, pear trees and cherries.
Iron deficiencies appear in fruit plants during the period of strong shoot growth, especially after a period of heavy rains. They are first visible on the youngest leaves. Leaves turn yellow-green, until yellow. With a large shortage, the tops of the shoots die. Fruiting is lowered, and the fruit becomes intensely colored.
They are very sensitive to molybdenum deficiency: cauliflower, Brussels sprouts and head lettuce. Symptoms of "hunger” this ingredient are: rot of the youngest heart leaves (at cauliflower) and drying of the edges and tips of the leaves.
Manganese deficiency is felt the most: pea (main shoots dry up), beans, spinach and tomato (visible minor, brown spots between the veins, evenly distributed over the entire surface of the leaf blade in the form of a "net”).
"Hunger” copper is found on peat soils. Its typical symptom is fruit dropping.
An overdose of soil fertilization with lime may cause symptoms of a lack of some micronutrients. A similar effect may be caused by too long fertilization with only simple mineral fertilizers, containing only macronutrients.