Already in the early days of life, young plants adopt nutrients from the ground with their newly developed rootstock. Therefore, in the initial stages of growth, when the rootstock is small, it is necessary to provide sufficient nutrients in the immediate vicinity of the plant so that growth can continue to flow smoothly. It is equally important that the entire soil layer, in which the root is developed, is supplied with nutrients so that the root of the plant growing to the depths finds new feed supplies. It is especially important to provide plants with sufficient nutrition until the plant's rest period during the winter. Only the crop that is well-fed and has entered the winter in good condition, can withstand the stressful winter conditions without the risk of decay. Also, well-fed crops will easily be subjected to nitrogen starvation at the beginning of spring if due to high soil moisture or low temperatures, the top-dressing is delayed.
The most important nutrients for normal growth and development of cereals are nitrogen, phosphorus, potassium, calcium, sulfur, manganese and iron. Nitrogen is important throughout the life of a plant, and is especially important to have it in sufficient quantity in the phase of ear formation and differentiation of floret into the ear, i.e. in the tillering and stem elongation phase and in the earing and grain phase. If there is not enough nitrogen at the beginning of the development, the leaf is narrow, it starts to yellow and eventually decays, the stems are thin and the tillering is weak. Phosphorus also influences the yield because it affects the development of root system and tillering stage. Phosphorus is essential for improving the absorption of nitrogen and increasing the resistance of plants to adverse conditions at the time of milk development and ripening of grain. The greatest requirements for phosphorus are during the first month after sowing of the crops, and during the time of the formation of pestil and stamens. Lack of phosphorus is manifested in weakening of the stem, late tillering stage, tiny foliage of blue-green color, and smaller ears. Potassium is also important in cereal feed though not as much as nitrogen and phosphorus. Lack of potassium is most evident in lower the grain quality. Calcium is a nutrient important throughout the life of the plant. Its lack causes underdevelopment of the root system. Calcium reduces the acidity of the soil, and the cereals grow best on slightly acidic to neutral soils, although some can withstand stronger acidic soils, such as oats.
The safest way to determine the required amount of feed in straw cereal fertilization is chemical analysis of the soil on whose basis sowing is planned.
The fertilization of winter cereals with mineral fertilizers begins in the autumn period by introducing fertilizers into the soil at the depth of ploughing. For this purpose NPK fertilizer grades with increased phosphorus and potassium content, such as NPK 7-20-30, are used. In basic fertilization of winter cereals, NPK 7-20-30 is applied in an amount of 200 to 600 kg / ha. In basic fertilization, the entire amount of required phosphorus and potassium feeds is introduced into the soil. An exception is the soil where feed losses are possible, such as light soils, shallow soils or due to large amounts of precipitation. In this case, 60% of the required amount of phosphorus and potassium is added in the basic fertilization and the rest is added in the pre-sowing or start fertilization.
If a larger amount of harvested residues are ploughed in, a larger amount of nitrogen should be applied, which will be used by the microorganisms in the process of degradation of the organic matter and thus the occurrence of nitrogen depression is avoided. When the harvest residues are ploughed in, 1 kg of nitrogen should be added to each 100 kg of harvest residues. For this purpose Urea or UAN is used in the amount of 100 to 150 kg (l) / ha.
Since the root of the plant is initially in the shallow layer and poorly developed, it is necessary to enrich this layer of soil by nutrients in pre-sowing fertilization, so that the just emerged plants are rooted better and continue to grow normally while saving energy for the upcoming winter conditions. In pre-sowing fertilization, fertilizers are introduced into the surface layer of the soil. In start fertilization, NPK fertilizer grades are applied with the same content of nitrogen, phosphorus and potassium as NPK 15-15-15 or NPK 20-10-10, in the amount of 150 to 250 kg / ha. If the complete amount of phosphorus and potassium is introduced into the soil by ploughing in, in pre-sowing nitrogen-sulfur fertilizer, PETROKEMIJas can be applied to the soil also in the amount of 150-250 kg / ha. It is important to emphasize that a complete amount of phosphorus and potassium should be introduced into the soil through the basic and pre-sowing fertilization to make the plants as good and deeper-rooted as possible. In the drought period, when the feeds in the surface layer of soil are completely inaccessible to the plant, well-rooted plants will be able to use water and dissolved nutrients from deeper layers of soil. Only well-fed crops can overcome stressful conditions and achieve expected yield and quality.