Agricultural chemistry lessons: phosphorus and potash fertilizers

Phosphate fertilizers affect the size of the crop, but even more - on its quality. A significant enrichment of all plant organs with them occurs when nitrogen in the ammonium form is present in the nutrient medium.

Phosphate fertilizers

Simple superphosphate

Simple superphosphate is a fast-acting phosphorus fertilizer. Powdered superphosphate - soft to the touch powder of gray or light gray (almost white) color - contains from 18 to 20% phosphorus oxide, up to 5.5% free phosphoric acid and up to 40% gypsum, which, when superphosphate is dissolved in water, remains in the form of a white precipitate ... Gypsum contains sulfur, which is also needed by plants (especially clovers). Superphosphate is produced mainly in the form of granules. In this state, it remains for a long time in a form accessible to plants, while the phosphorus of powdered superphosphate is absorbed by plants slowly. Fertilizer can be applied before sowing, during sowing and used for fertilizing after sowing.

Superphosphate double

Double superphosphate - the main phosphoric highly concentrated fertilizer - contains 40-50% of assimilable P2O5. Its properties are close to simple superphosphate, but does not contain gypsum. It can be obtained from relatively low-percentage phosphorites.

Phosphorite flour

Phosphorite flour - a fine earthy powder from light to dark gray or brown - contains 16-22% or more of phosphorus oxide in a poorly soluble form. Obtained by grinding natural phosphates. On acidic soils, finely crushed phosphorite flour into a state assimilable by plants gradually passes, decomposing under the influence of soil acidity, first to two-substituted calcium phosphate. It is well absorbed buckwheat, mustard, sainfoin, peas.

Potash fertilizers

They, as a source of natural radioactivity, are of particular importance in plant life - beta and gamma rays create additional intracellular energy, which takes part in all biochemical processes.

A group of so-called potassium-loving crops has been identified: sugar beet, fodder roots, vegetable crops, corn, potatoes, gooseberry.

With the crop, much more potassium is removed than phosphorus, and sometimes even more than nitrogen. This is especially true for potatoes, root crops, cabbage... Perennial legumes and grasses consume a lot of it. Potassium naturally returns to the soil with fallen leaves, stems (straw) and other crop residues.

Potassium chloride

Potassium chloride - the main potash fertilizer - contains from 54 to 62% potassium oxide (K2O), is a white fine-crystalline or large-crystalline reddish substance. White potassium chloride contains 62–62.5%, reddish — 54–60% K2O; the latter, due to its lower hygroscopicity, is better stored (less caking).

Potassium salt

Potassium salt, a fertilizer obtained by mixing potassium chloride and ground sylvinite, contains 41-44% K2O. The presence of sodium in the fertilizer has a positive effect on the sugar content of sugar and fodder beet roots, making potassium salt especially useful for these crops.

Wood ash

Wood ash - an alkaline potash fertilizer - contains 7-13% K2O, enriches the soil with potassium, and also reduces acidity with phosphorus and trace elements due to the presence of potash (K2COz) in the ash. Wood ash is stored indoors (water washes away nutrients). As a chlorine-free fertilizer, it is especially valuable for potatoes.

A. Kotousova

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