Calcium fertilizers

Lime fertilizers are used for liming, the main purpose of which is to change the acidity of the soil, not corresponding to most of the arable crops. Calcium fertilizers can be divided into five groups according to their chemical composition:

– fertilizers containing calcium in the form of calcium oxide (CaO),

– fertilizers containing calcium in the form of calcium carbonate (CaC03),

– mixed fertilizers containing some calcium in the oxide form and some in the carbonate form,

– calcium silicate fertilizers,

– magnesium calcium fertilizers.

Calcium fertilizers are also obtained as post-production industrial waste.

Oxide fertilizers, which is represented in practice by the quicklime used, are powerful fertilizers and therefore they are used on heavy and medium soils, at least 2-4 weeks before sowing seeds or planting plants. Burnt agricultural lime contains 80-60% CaO. It is a finely divided fertilizer and may cause eye and skin irritation during its spreading; therefore it is recommended to mix it with the soil before sowing.

Carbonate fertilizers are slower-acting and non-corrosive fertilizers, therefore, they can be used at any time of the year and for all types of soil. Due to their slow action, it is recommended to use them on light soils and shortly before sowing or planting plants. Of these fertilizers, common agricultural chalk contains 45% CaO in carbonate form, and defecation lime – 20-50% CaO in carbonate form (a waste product of the sugar industry). Ground limestone, obtained by grinding limestone rock, it can even contain up to 99% calcium carbonate, mostly 70-90%, which corresponds 40-50% CaO. It is easy to sow and is non-corrosive.

Lime mixed fertilizers are a combination of quicklime and ground lime in a ratio of approximately 1:1.

Many other types of calcium fertilizers are also used for liming soil, which are by-products of various industries. These include the soda lime, obtained in the production of soda (do 90% CaCO3), post-cellulose – a by-product of the pulp and paper industry (ok. 90% CaC03), poke-lime, obtained in the production of sulfuric acid from sulfur-bearing ore (ok. 80% CaC03), carbide lime – a by-product of the production of acetylene, flotation lime, obtained when leaching sulfur from ore containing quite large amounts of CaCO 3 (above 80%), defecation lime, mentioned above.

Wanting to determine the amount of calcium dose, you have to know the reaction (pH) soil. For liming light soils and for plants sensitive to freshly limed soil, e.g. pod: pumpkin, beans, pea, carrot, cucumber, tomato, parsley, celery, and also under: gooseberry, raspberry and strawberry, one-time amount of calcium should not be more than 10-15 kg CaO na 100 m2 (in slow-acting fertilizers), and for liming heavy soils – no more than 15-20 kg CaO na 100 m2 (in fast-acting fertilizers). The table provides guidance on the dosage of calcium fertilizers [9],

Liming is usually carried out in the autumn period. If for some reason this treatment is not performed in the fall, it can be carried out in the spring, except that then you have to apply (regardless of the type of soil) calcium fertilizer only in the form of carbonate. Lime fertilizers should be spread evenly over the entire surface of the garden. After sowing, they should be mixed with the soil using a spade, digging the soil to the depth 15-20 cm. When liming the soil under older trees, the fertilizer must be sown on an area corresponding to the range of individual tree crowns and also mixed with the soil. When spreading dusty fertilizers, rubber gloves and protective goggles must be worn; they should be sown in the direction of the wind. Borax can be used for borax fertilization, which contains 11% pipe.

Table. Approximate doses of CaO per 100 m² ground surface