Using Potash Fertilizers (part 1)

2023 Author: Sebastian Paterson | [email protected]. Last modified: 2023-11-26 20:34

The mysteries of potash fertilizers

Potassium is one of the mysterious elements in plant nutrition. If nitrogen, phosphorus and other nutrients form strong organic compounds, that is, they are the building blocks of which the entire cell and the plant as a whole are built, then potassium does not form such strong organic compounds.

His role is somewhat different and, perhaps, more complex. It comes down to managing the construction processes, the movement of nutrients and plastic substances both through the plant and from the soil to the root. And this is the most important function. Serving food on time and in the right place is what begins the process of optimal plant nutrition and growth.

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Potassium in the plant

Potassium belongs to the elements, of course, necessary for animals, plants and microorganisms. Most of it (at least 4/5 of the total content) in the plant is in the cell sap and is easily extracted with water; the smaller one is adsorbed by colloids and insignificant (less than 1%) is absorbed by mitochondria in the protoplasm. While retaining light mobility, potassium is still more strongly retained during the day in a plant illuminated by the sun and is strongly released back into the soil through the roots at night, and the next day it is again absorbed, accumulates and all night losses are completely restored. At the boundaries of cell membranes, between the root and the soil solution, a kind of "potassium pumps" work, when instead of the released potassium, other nutrients are supplied from the soil to the root.

Rain also leaches a significant amount of this element from the leaves and stems; after rainy weather, the need for potassium in plants increases greatly.

Potassium in the plant is distributed unevenly: it is more in those organs and tissues where metabolic processes and cell division are intensive (this is the meristem, young shoots, buds, etc.). There is a lot of potassium in pollen, in ash, which contains up to 35% of it, while taken together calcium, magnesium, sulfur and phosphorus there is only about 25%.

The radioactive properties of potassium play an essential role in plant life. In living and inanimate nature, it is in the form of a constant mixture of three isotopes: 39K (93.08%), 40K (0.011%) and 41K (6.91%), where 40K is a radioactive isotope with a half-life of 1.3x109 years. Radioactive rays of potassium significantly increase the energy balance of the plant, and in the frog, for example, they stimulate the contractions of the heart.

In potato leaves, the potassium content is on average 1.5%, in its stems - 1.89%, in the roots - 0.14%. More than 96% of potassium (K2O - the potassium content in plants, soil and fertilizers is usually expressed in terms of its oxide) is contained in tubers, which gives potatoes medicinal properties. Therefore, potato juice and its decoctions are used to treat many human diseases.

The importance of potassium in plant life is diverse. It promotes the normal course of photosynthesis, increasing the outflow of carbohydrates from the leaf blade to other organs, such as fruits, as well as the synthesis and accumulation of vitamins in plants - riboflavin, thiamine. Although potassium is not included in enzymes, it activates the work of many of them (pyruvic acid kinases, enzymes that enhance the formation of peptide bonds, and, consequently, the synthesis of proteins from amino acids). This element increases the hydrophilicity (water content) of protoplasmic colloids, due to which plants can more easily tolerate short-term droughts. With good potassium nutrition, plants better tolerate frosts and low temperatures in winter, and potassium deficiency greatly inhibits protein synthesis and the formation of sugars.

It is assumed that potassium salts serve as conductors of biocurrents (like the nervous system) that transmit irritation reactions from organ to organ in a plant organism.

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With a lack of potassium, the development of crops and their maturation are delayed. Under conditions of good potassium nutrition, the sugar content in fruits and vegetables, starch in potatoes, increases, the osmotic pressure of the cell sap, and, consequently, the winter hardiness of crops. The value of the supply of plants with potassium increases with good ammonia nutrition, while more proteins are formed, nitrogen is better absorbed. When potash starvation lowered yield and quality, and resistance to diseases of fungal pathogens in plants during growth and during storage.

For 1 centner of marketable products (with the corresponding amount of non-marketable products) sugar beets consume 0.55-0.75 kg of potassium, potatoes - 0.67-0.92, peas about 3.5, cabbage - 4 kg. Almost all plants and microbes consume significantly more potassium than phosphorus to create a crop. Therefore, to restore fertile potassium reserves in soils and increase yields, potash fertilizers should be applied from 8 to 30 g / m² of active substance.

External signs of potassium starvation are manifested in the browning of the edges of the leaves (they seem to become burnt - "edge burn") and the appearance of rusty specks on them; these signs are found in plants when the potassium content in them decreases by 3-5 times against normal.

The dynamics of potassium intake in plants is as follows (cumulatively): in June 20, in July 80, in August 98, in September 100%. The maximum occurs in July, within a month the plant takes out 60% of the potassium it needs from the soil, therefore it is very important to apply potash fertilizers in the spring for digging the soil in order to properly meet the needs of the plant.

The amount of potassium in plants decreases relatively with their age. The decrease in potassium with age is also associated with its washing out of the leaves by rains. The ability of potassium to be retained in the aboveground part from leaching by rains and in the roots from passing into an external solution depends on the supply of the plant with nitrogen. With nitrogen and in the light, more intensive growth takes place, stronger labile bonds of this element with some organic compounds are formed. However, in the dark, such bonds cease to function, and potassium easily passes from the roots into the soil.

Different crops consume different amounts of potassium. Fruit and berry plantations, sugar beets, cabbage, root crops, potatoes, sunflowers, legumes, corn require relatively much of this element, therefore these plants are called potassium-loving. Less potassium is found in rye, wheat, oats and barley crops.

With animal feed and straw going to bedding, significant amounts of this nutrient end up in manure, where it is concentrated in the liquid fraction. Therefore, proper storage of manure (without loss of slurry) and its rational use are of great importance to meet the needs of agricultural plants in potassium. However, manure alone is not enough. An important role belongs to industrial mineral potash fertilizers, which make it possible to obtain high-quality vegetables and fruits and berries.