What is potassium? What's their purpose? (with specific application methods)

The existence form of potassium is different from that of nitrogen and phosphorus, it mainly exists in ionic or soluble salts or adsorbed on the protoplast surface, rather than in the form of organic compounds. So what are the excellent potash fertilizers? As excellent potassium sources, fertilizers include potassium nitrate, potassium sulfate, potassium dihydrogen phosphate, potassium chloride and so on. Today, the editor has collected some information about these fertilizers and shared them with you.

Potassium nitrate:

Potassium nitrate is a colorless crystal with low hygroscopicity, easy caking, good physical properties and convenient application, so it is a good water-soluble potash fertilizer. Potassium nitrate is a chlorine-free potassium and nitrogen compound fertilizer. The total content of potassium and nitrogen in plant nutrients can reach about 60%. It has good physical and chemical properties.

It contains 13.5% nitrate nitrogen and 46% potassium. It is chemically neutral and physiologically neutral fertilizer with good water solubility. Long-term application will not lead to soil acidification. It is suitable for the expansion period of young fruit of fruit trees to the initial stage of coloring, and can promote the expansion of pulp cells. Due to the presence of nitrate nitrogen, it is not recommended to use it in the later stage of coloring, which is easy to turn green.

Potassium nitrate has the following advantages:

(1) since there is no volatility, it can be applied directly to the soil surface without mulching.

(2) the application of nitrate nitrogen to chloride sensitive crops is more beneficial than ammonium nitrogen, such as oranges, grapes, vegetables, sugar beets and other crops sensitive to chloride ions, because the nitrate nitrogen in potassium nitrate can prevent crops from absorbing chlorine in the soil.

(3) nitrate nitrogen can provide nutrients quickly under any conditions, which is suitable for spring, summer, autumn and winter crops.

(4) it will not cause salt accumulation in the soil.

(5) potassium nitrate is a kind of high efficient compound fertilizer containing potassium and nitrogen, which can achieve good results in all kinds of soil and crops, especially suitable for chlorine-avoiding crops, such as tobacco, tomato, citrus, glucose, etc.

(6) the price of potassium nitrate is higher than that of potassium sulfate, but the ratio of performance to price is also higher.

Second, potassium dihydrogen phosphate:

It contains 52% phosphorus (P2O5) and 34% potassium (K2O). It is chemically neutral, physiologically neutral fertilizer and has good water solubility. Generally, before and after flowering, it can be used to promote root germination and flower bud differentiation, provide energy for flowering and fruit setting; use during coloring period can promote powder coloring and increase fruit sweetness; use after fruit picking can promote branch ripening and improve fruit Lignification.

Many people ask, which is better, potassium nitrate or potassium dihydrogen phosphate?

In fact, there is no such thing as the better one. The key is how to use it. Both of them contain different elements. Potassium nitrate is a binary compound fertilizer of nitrogen and potassium, and potassium dihydrogen phosphate is a binary compound fertilizer of phosphorus and potassium. Therefore, it is necessary to adopt different products according to different periods. The nitrate nitrogen in potassium nitrate is easily lost by rain, so it is generally not recommended to be used in paddy fields.

With regard to potassium nitrate and potassium dihydrogen phosphate, it can be understood that when crops use a large amount of nitrogen, potassium nitrate is used; when crops need more phosphorus, potassium dihydrogen phosphate is used. Potassium nitrate was used in the expansion period and potassium dihydrogen phosphate was used in the coloring period. Potassium nitrate is used in the normal growth period and potassium dihydrogen phosphate is used in the flowering and fruiting period. Strictly speaking, these two products should not be regarded as pure potash fertilizer. Even potassium dihydrogen phosphate is classified as phosphate fertilizer in many categories.

Both of these fertilizers are quick-acting fertilizers, and the market price is higher than ordinary potash fertilizer, so it is not recommended to use as base fertilizer, especially potassium nitrate, for topdressing or extra-root fertilization. If there are conditions, you can use the two together, it will be better. These two things are used in many high-end raw materials of water-soluble fertilizer. Some friends said that the water-soluble fertilizer with potassium nitrate and potassium dihydrogen phosphate as raw materials should be the conscience product of the industry.

The most important point is that the domestic quality of these two things is OK as long as they are regular manufacturers, and there is no need to use imported ones.

3. Potassium sulfate:

Theoretically, the potassium content is 54%, generally 50%; it is a chemically neutral and physiologically acidic fertilizer with good water solubility, but long-term use will aggravate soil acidification, which is suitable for grape coloring from late coloring to fruit ripening, promoting fruit powder coloring and increasing fruit sweetness.

Response to the application of potassium sulfate in different soils and matters needing attention:

The main results are as follows: (1) in acidic soil, excess sulfate will aggravate the acidity of soil, and even aggravate the toxicity of active aluminum and iron to crops. Under the condition of flooding, too much sulfate will be reduced to hydrogen sulfide, which makes the root black. Therefore, long-term use of potassium sulfate should be combined with farm fertilizer, alkaline phosphate fertilizer and lime to reduce acidity, and in practice should be combined with drainage and drying measures to improve ventilation.

(2) in calcareous soil, sulfate ion reacts with calcium ion in soil to form insoluble calcium sulfate.

(3) the application of potassium sulfate in taboo crops, such as tobacco, tea tree, grape, sugarcane, sugar beet, watermelon and potato, can not only increase the yield, but also improve the quality. Potassium sulfate is more expensive than potassium chloride and has less supply, so it should be used in cash crops that are sensitive to chlorine and like sulfur and potassium, and the benefit will be better.

(4) potassium sulfate should not be mixed with calcium-rich fertilizers.

It is said that manganese poisoning in many fruit tree areas is caused by soil acidification, and the direct cause of soil acidification is the perennial use of potassium sulfate. Therefore, fertilizer, nothing to change, do not always use one, you keep eating the same thing will also cause malnutrition, not to mention the land.

IV. Potassium chloride

Potassium chloride [KCl, containing 60.0% K2O (50.0%)] occupies a major position in potash fertilizer because of its high potassium content, rich resources, simple processing and low price. The industrial production of potassium chloride began in Germany in 1861. At present, Canada, the former Soviet Union, Germany, France and the United States have higher production. The five countries account for 95% of the world's total output.

Potassium chloride is currently the most widely used potash fertilizer in the world, accounting for more than 90% of the total potash consumption. Potassium chloride is not only directly used as a basic fertilizer for potash fertilizer or mixed fertilizer, but also a basic potassium source for the production of chlorine-free potassium fertilizer such as potassium sulfate, potassium nitrate or potassium phosphate. Pure potassium chloride is a white glossy crystal with a solubility of 34.4% in water at 20 ℃ and slightly soluble in liquid ammonia (0.102% at 18.9 ℃) and ethanol (0.290% at 25 ℃). The appearance of commercial potassium chloride is light yellow, brick red or white, crystalline or granular, with low free water content and certain hygroscopicity. Potassium chloride from Canada is light brick red because it contains about 0.05% iron and other metal oxides. Granular (0.8-4.7mm) or coarse-grained (0.6-2.3mm) potassium chloride, mainly used for mixing fertilizers in bulk. When potassium chloride is 20 ℃, the relative humidity is 88.3%. After entering the soil solution, it is very easy to dissolve, and the salt index reaches 116.

After potassium chloride was applied to the soil, K + was easily absorbed by soil colloidal particles and also easily absorbed by crop roots, and relatively more Cl- remained in the soil and interacted with cations such as Ca2+,Mg2+ on soil colloidal particles or H + exchanged from the root surface to form highly mobile CaCl2,MgCl2 or HCl, which could eluviate calcium, magnesium and other bases in the soil around the fertilization site, and may acidify the soil. Therefore, KCl is also a kind of physiological acid fertilizer, which is continuous in acidic soil, and it has the side effect of acidified soil when it is used. Therefore, when using KCl in acidic soil, it is necessary to apply a certain amount of lime or fertilizer containing calcium and magnesium, and it can also appropriately reduce the amount of KCl used each time or intermittently.

Potassium chloride contains 45% MUR 47% chlorine. Although Cl- is also an essential nutrient element for crops when it is applied to the soil, the crop requirement is small, which is only 1x20-1x10 of the crop requirement. Therefore, in the continuous use of a large number of KCl, crops are easy to inhale too much Cl-, to affect the product quality of some cash crops, such as reducing the sugar content in grapes and fruits, reducing the flammability of tobacco, increasing the water content of potatoes and so on.

Potassium chloride also contains a certain amount of sodium chloride (1% Mel 3%), which is generally not suitable for use in saline-alkali soil. When potassium chloride is used in neutral and calcareous soils, it is easy to cause downward leaching of the base. The continuous downward leaching of the base in the soil will make the base unsaturated in some soil or local soil layer, resulting in the change or even deterioration of its physical properties, so attention should be paid to the application of a certain amount of fertilizer containing the base.

Potassium chloride can be used as base fertilizer and topdressing fertilizer, both of which should be deeply applied to the wetter layer of the topsoil. Generally, it is not used as seed fertilizer or extra-root topdressing. Tobacco, grapes, potatoes and other taboo crops, in principle, should not be applied separately or continuously, and must be applied with caution.

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