MINERAL FERTILIZERS
Mineral fertilizers usually contain only one main nutrient and are therefore divided into groups according to their ingredient, which they contain. The following groups of mineral fertilizers are distinguished:
– nitrogen fertilizers,
– phosphorus fertilizers,
– potash fertilizers,
– magnesium fertilizers,
– calcium fertilizers,
– micronutrients,
– multi-component fertilizers.
Mineral fertilizers can be characterized in points.
1. They contain nutrients, which are a measure of the useful value of mineral fertilizers. Their content is known as the pure component. Thank you, the nitrogen content was taken as the pure component (N) in nitrogen fertilizers, phosphorus oxide (P205) – in phosphorus, potassium oxide (K20) – in potassium and calcium oxide (CaO) -in calcium fertilizers. The conversion of the fertilizer into the pure component and vice versa is as follows:
pure ingredient =(freight mass) x (the nominal content of the pure component in the fertilizer) / 100
commodity mass of the fertilizer = the sum of the pure x component 100 / % pure ingredient in the fertilizer
2. They are defined according to the degree of fragmentation. This is an important feature, affecting the use of nutrients from some sparingly soluble fertilizers. In order to reduce the absorbent surface of powdered fertilizers, granular fertilizers are produced. Granular fertilizers must have a strictly defined granulation size and the permissible amount of undersize and oversize. Deviations from the norm affect the deterioration of the fertilizer performance and difficulties in mechanical sowing.
3. Looseness affects the sowing capacity, which is primarily important in the mechanization of this activity.
4. The water content varies widely, depending on the type of fertilizer, e.g. in urea is 0,3%, and in powdery superphosphate to 13%. It is covered by the standard; if it is exceeded, the physical properties of the fertilizer deteriorate (such fertilizer has a lower utility value).
5. The content of impurities in fertilizers is also subject to standardization, in order to avoid excessive concentration of some components harmful to plants, e.g. free acids, metals.
Nitrogen fertilizers, depending on the chemical composition, is divided into four groups.
1. Nitrate fertilizers, that is, nitrate. Synthetic sodium nitrate, produced by synthesis from atmospheric nitrogen, is a light yellow fertilizer, containing 15,5% nitrogen in nitrate form. Calcium nitrate – flog wapniowy, obtained by the action of nitric acid on calcium carbonate, contains 15,5% nitrogen. Due to its high hygroscopicity, it is produced in granules, in white (in Poland, it ceased to be produced from 1975 r ). All saltpeter are easily soluble in water. They are physiologically alkaline fertilizers, fast acting. They are suitable for all types of soil and for plants that do not tolerate acid conditions. Due to the possibility of washing out saltpetre, they are usually used for top dressing, i.e.. during plant growth, scattering in the rows, dividing the scheduled dose into 2 or 3 parts, that plants make better use of the given nutrients.
2. Ammonia fertilizers: ammonium sulfate and ammonia water. Ammonium sulfate contains 20,5-21% nitrogen. It is a crystalline fertilizer, non-hygroscopic, white-cream color and – unlike saltpetre – physiologically acidic. It is a typical pre-sowing fertilizer. After sowing, it should be carefully covered with soil. Ammonia water contains 20,5% nitrogen. Unlike ammonium sulphate, ammonia water causes the soil environment to become alkaline.
3. Ammonium nitrate fertilizers: saletra amonowa i saletrzak. Ammonium nitrate contains 34% nitrogen: some in ammonium form and some in nitrate form. It is easily soluble and absorbs water (hygroscopic fertilizer). It works just as fast, as well as other saltpeter, but it is not so easily washed out into the ground; therefore it can also be used before sowing. Used for top dressing, it needs to be covered only on alkaline soils. Calcium ammonium nitrate is a mixture of ammonium nitrate and finely ground calcium carbonate. Saletrzak, similar to ammonium nitrate, contains half of the nitrogen in the form of nitrate, and half as ammonium. The addition of ground calcium carbonate reduces the hygroscopicity of this fertilizer, and also lowers the nitrogen content to 25-28%. Ammonium nitrate is suitable for all crops. It can be used before sowing and top dressing. Requires covering with soil.
4. Amide fertilizers – urea. Urea is a water-soluble fertilizer, therefore it easily penetrates into the soil. It has a high nitrogen content – 46%. It does not contain any side ingredients, it is therefore the most concentrated, and with proper use, very good nitrogen fertilizer. Urea can be used before sowing, for top dressing and foliar application. Its good operation is ensured especially by soils with the so-called. high culture.
Application and action of nitrogen fertilizers, as well as other mineral fertilizers, depends on the properties of a given fertilizer, his dose, the sowing date, soil properties and the fertilization needs of plants. On acidic soils, physiologically acidic fertilizers should not be used, because they would acidify the soil even more. The choice of nitrogen fertilizer also depends on this, whether it is used pre-sowing or top dressing. The size of the doses depends on the soil fertility, doses of organic fertilizers, which also contain nitrogen, and on the nutritional requirements of plants. The amount of nitrogen, used by plants from nitrogen fertilization, is on average 50-60%, sometimes it comes to 95%. Nitrogen from the balance is best used 95%.