The division of the chemical form is divided into chloride, chloride-free and sulphate fertilizers.
Due to the methods of application, there are granular fertilizers used for top dressing or pre-sowing, and foliar fertilizers supplied by leaves. We mostly find phosphorus-potassium fertilizers. Comprehensive solutions in various compositions; Phosphorus-nitrogen, nitrogen-potassium, phosphorus-magnesium and potassium-magnesium.
Depending on the type of soil, crop, and destination, considerations such as type, dosage, and formulation and method of application will vary significantly. For example, for ornamental plants we mostly use foliar fertilizers available on the market. In turn, on larger acres and heavier soils, we use granulated fertilizers introduced as soon as possible in the autumn before sowing. On lighter soils, potassium is quickly leached out. This makes it possible to hydrolyze and decompose fertilizers from complex forms that are accessible, digestible and available for plant uptake.
The choice of fertilizer and its frequency of application should be justified by the previous soil analysis and knowledge of its content in the soil according to the agronomic category and its usefulness and production intensity.
Potassium is one of the most important plant nutrients that determines the yield and quality of crops. Potassium is responsible for water management. Therefore, it is justified to use it, especially in the situation that we have dealt with in recent years.
Potassium affects many important processes in the plant, namely:
Potassium deficiency in the plant limits the transformation of mineral nitrogen into proteins. With a potassium deficiency, plant growth is inhibited, accretions are thin and internodes are shortened. Leaves develop necrotic spots between the veins, which vary from plant to plant. Initially the leaves turn dark and dull, turning yellow at the tips and edges of the old lower leaves. Leaf blades fold, curl from the edges, crack and then turn brown. Symptoms of a lack of potassium in the plant can be easily recognized by the characteristic necrosis of the leaf edges.
Tomatoes, peppers, cereals, beets, potatoes, rapeseed, peas, field beans, beans, cabbage, cauliflower, leeks, onions, lettuce, fruit trees and shrubs, and berry plants are particularly sensitive to potassium deficiency. Excessive potassium fertilization may also cause a deterioration in the quality of the crop, e.g. apple bitter blotch or dry rot of tomatoes in relation to the salinity of the substrate. Potassium overfertilization is very dangerous for orchards and berry plantations, as it stimulates the deficiency of magnesium, boron and calcium.
Too high potassium fertilization leads to the characteristic symptoms of a lack of magnesium on the leaves. Too high doses of potassium cause its excessive accumulation in the plant, mainly in the green part and roots (except seeds). This significantly affects the deterioration of the technological, biological and storage value of the crop.
Potassium is an antagonist to magnesium and therefore blocks the uptake of magnesium as well as its movement in the plant.
Under average conditions on light soils, the total dose of potassium, both for autumn sowing and spring crops, should be divided between autumn and spring (several days before cultivation) in the ratio 2/3 : 1/3. On heavy soils, in turn, the entire planned dose of potassium should be applied in the fall. Such action allows to ensure the optimal level of plant fertilization, and winter crops to prepare well for winter rest. Fall fertilization of soils with potassium allows the element to move in the soil, from where the plant can take it freely and for a long time from deeper layers of the soil profile.
If the autumn potassium fertilization was not done, it is worth supplementing the element as soon as possible. Potassium fertilizers can be used not only in autumn, but also later (late autumn, winter and early spring), provided that the principles of good agricultural practice are complied with. For this purpose, it is worth taking advantage of ground frosts.
It should be remembered that mineral fertilizers cannot be used on flooded soils, covered with snow, frozen to a depth of 30 cm and during rainfall. Manure sown on frozen soil or snow cover is exposed to dissolving in melting water and, consequently, running off the field.
The prices of potassium fertilizers in recent years fluctuate from PLN 1,200.00 to PLN 1,395.00. The differences are due to several reasons. One of them is the fact that Poland does not have a source of obtaining this element on such a scale to be able to do it. For this reason, the potassium salt is mainly of Belarusian and German origin. Secondly, prices are converted to the euro exchange rate and here they can also change by 10 percent or more during the season. The price is also influenced by the global situation of average yields in the EU and in countries affecting the trade in agricultural products.