Phosphorus fertilizers are made from phosphate rock or apatite, whose deposits in Poland are unfortunately not suitable for exploitation, due to the low percentage of phosphorus compounds. Phosphate fertilizers include: single superphosphate (dusty and granular), triple granulated superphosphate, granulated triple superphosphate with boron, phosphate rock meal and bone meal. These fertilizers are not soluble in water, therefore they must be well mixed with the soil.
Superphosphate is a mixture of many compounds, the most important of which is monocalcium phosphate. Apart from this component, they are found in super-phosphate: calcium sulfate, phosphoric acid and sulfuric acid. Domestic produced superphosphate (granular superphosphate) contains 18 or 19% P2O5 It is soluble in water, so it is easily absorbed by plants. Superphosphate is light gray in color, it is slightly hygroscopic, moist to the touch. It is mainly suitable for more compact soils, o pH 6-7. The use of powdery superphosphate on very light soils should be avoided, peat, acidic and ferruginous, as phosphorus is easily reversible. This process is prevented by granulating it.
Triple Superphosphate is a concentrated fertilizer (46% P205), containing water-soluble phosphorus. It differs from the single one with a high content of phosphorus and the lack of calcium sulfate (plaster). It is produced in a granular form, thanks to which it retains phosphorus compounds for a long time in the soil, water-soluble. It is a universal fertilizer, suitable for all plants and soils, except very acidic.
Granular triple superphosphate with boron, the so-called. drilled, contains 44% P205 i 0,5% B (pipe). It is a concentrated fertilizer. The addition of boron makes this fertilizer particularly useful for plants that require fertilization with this component. This fertilizer, water-soluble, is a universal fertilizer, well used by plants. Suitable for all plants and all types of soil, especially on acidic soils, freshly limed.
Phosphate rock meals are ground minerals, their fertilizing value depends to a large extent on the phosphate rock used and the degree of grinding: the greater the degree, the better the effect of this fertilizer. Phosphate rock flour contains approx 29% P206 and are particularly suitable for acidic soils and areas with high rainfall. This fertilizer works slower and longer, more than once in the third year after spreading.
Bone meal is the oldest phosphorus fertilizer; it also contains some nitrogen. It is obtained by degreasing the bones, removal of glue and grinding. It contains approx 30%
P205 and approx 1% nitrogen. It is used as a component in horticultural lands, intended for the cultivation of ornamental plants in pots, on balconies or in greenhouses – in the proportion of approx. 4 kg of bone meal per 1 m3 of land.
Using the fertilizing properties of these agents, they are used for orchard plants before deep soil digging, which are performed in the fall. Phosphorus fertilizers can also be applied before sowing cover crops, thus increasing the yield of green mass. Superphosphate is used for vegetable and ornamental plants in spring, and rock phosphate meals – in the fall. Due to minimal phosphorus losses due to leaching, phosphorus fertilizers can be used "in reserve", tj. doses can be used instead of the annual phosphorus fertilization 3-4 times bigger once a 3-4 years.