5. Methods of applying chemical fertilizers
Pentru utilizarea eficienta a ingrasamintelor chimice, modul si perioada de administrarea prezinta o importanta deosebita.Stabilirea modului corect de administrare a ingrasamintelor chimice este factorul care determina eficienta acestora.Trebuie urmarit ca substantele nutritive sa fie cat mai mult in zona radacinilor active ale plantelor.
Perioada de administrare
The period of application differs according to the pedologic and climatic conditions, as well as to the plant’s maximum consumption stage. Through its physical, chemical and biological features, the soil greatly influences the period of applying the fertilizers. During the sprouting period it is very important that enough quantities of nutrients are present in the area where the plant’s roots appear. This is the main criterion in establishing the optimum period of applying the fertilizers. Although a standard calendar could not be recommended, it is possible however to establish some general characteristics regarding the application of fertilizers, taking into account the basic nutritious elements.
Nitrous fertilizers are very active in soil and can be easily washed away by the pluvial waters or by irrigations. To prevent these losses, these fertilizers will be applied when they are most needed; most often than not the quantity of nitrogen is not applied all at once during the seeding period or the growing period but the application is made gradually, in certain stages of evolution of the plants. In the case of grains, urea is applied during seeding because, due to washing, it has little losses in the soil. Before sprouting, fertilizers based on ammonium nitrate and calcium (calcium ammonium nitrate) will be applied. Instead of these, one can use urea, especially before rain. In Romania, the pedologic and climatic conditions recommend the use of nitrous fertilizers (even the complex ones) in a fractioned manner, half in autumn, when preparing the germinative bed or immediately after seeding, and the other half in spring when the vegetation starts, on soil clear of snow. If a deficiency of nitrogen is noticed in the fructiferous trees plantations, in autumn and before blossoming, urea will be pulverised in concentration of 0.5- 1.0%. Nitrogen based fertilizers may be applied in the soil, around the tree, under the protection of the crown, which can afterwards be incorporated into the soil with the help of a rake.
In the vineyards, half of the nitrous fertilizers will be applied during the February-March works and the other half will be applied as urea after the first hoeing. As far as vegetables are concerned, the fertilizers are applied once or twice taking into account the vegetation period. The application is done in two stages, half 15 days after planting and the rest after the fruit are yielded, the fertilizer being applied approximately 10/15 cm from the plant’s stalk and well mixed with the soil.
According to the period of application, there are 3 distinct variants as follows:
- fertilization before seeding/planting called basic fertilization;
- fertilization during seeding/planting;
- fertilization during vegetation;
- fertilization after seeding/planting.
It combines with the soil working system, along with the deep ploughing under the bed. Fertilizers can also be incorporated in the works before seeding; in this case, the easily soluble fertilizers will be applied, which will be used by the plants at the beginning of the vegetation period in the case of annual crops (grain, vegetables, and fodder plants).
Fertilization during seeding/planting
For the plants that are seeded in rows or crates, the fertilizers are applied with special seeders which leave on the same row or in the same crate both the seeds and the fertilizers. Such fertilization ensures the nutrition of plants for 20/30 days after sprouting. In the case of corn, one of the plants that have the best reaction to chemical fertilizers, they are applied in 2 stages :
- before seeding or during seeding, on the row, 5-6 cm laterally from the seed and 2-3 cm under it;
- in the stage when the plant has 5-7 leaves, still on the row, using the cultivator equipped with fertilizer applying devices.
It is also called supplementary fattening and its purpose is to make up for the plants’ need for nutrients during certain critical periods of their nutrition.
Manner of applying the fertilizers
Establishing the right manner of application is what determines the fertilizers’ degree of efficiency. There are 4 main methods:
- by spreading;
- by incorporating as strip, on the row, laterally or vertically;
- by spraying on leaves;
- along with the irrigation water.