Potassium monophosphate: instructions for use, composition and application rates for different crops

What it is?

Potassium monophosphate is a completely water-soluble compound that is well absorbed by all crops. It is used for spraying and application when irrigating with water in unprotected soil, as well as in greenhouses and greenhouses.

Many manufacturers also use another name for potassium monophosphate - monopotassium phosphate, what is the difference? This is practically the same compound with the chemical formula KH2PO4. It contains about 34% potassium oxide and 52% phosphorus oxide.

On the packaging, where it says “monopotassium phosphate,” only a slight difference in the proportion of the main substances is noticeable: the potassium part is 33%, and the phosphorus part is 50%. The rest is phosphoric acid. The only difference is in concentration, which does not play a significant role.

These appear to be light beige, light brown or white granules (powder) that quickly dissolve in water, especially warm and hot water.

Potassium monophosphate - features and composition

Potassium monophosphate, which is also known as monopotassium phosphate, is a complex mineral fertilizer used both on private plots and on an agricultural scale. The formula of potassium monophosphate is KH2PO4.

Monopotassium phosphate is a highly soluble substance that dissolves instantly in water, allowing you to get quick results. The substance is available in the form of powder and granules.

The composition of potassium monophosphate fertilizer is represented by phosphorus 50-55% and potassium 33%:

Potassium – normalizes water-salt metabolism in plants, increases their immunity to various infections and diseases. Potassium stimulates the saturation of fruits with starch and sugars, improving their elasticity and taste.
Phosphorus - participates in plant photosynthesis, promotes rapid growth of vegetative mass, formation of ovaries and strengthening of the root system.

When applying potassium monophosphate fertilizer, orthophosphoric acid is formed, which is quickly absorbed by plant cells and does not have a negative effect on the soil structure.

Indications for use

Potassium monophosphate or potassium salt of orthophosphoric acid is added if symptoms of potassium or phosphorus deficiency appear:

abundant flowering of fruit trees and berry bushes, but after it there are small fruits and no fruit at all;
leaves are wrinkled, similar to corrugated paper, twisted into a tube;
yellowing and then browning of the leaves, their downward tilt, the dying off of the foliage along with the cuttings;
thinning of shoots;
growth arrest at the peak of the growing season.

Monopotassium phosphate is useful in early spring, especially if frosts have persisted or the weather has been rainy for a long time. It performs well on peat-bog, sandy loam sod-podzolic, sandy, gray forest soils, and southern chernozems.

The need for phosphorus and potassium also increases if the soil contains large amounts of lime.

Moreover, the combination of phosphorus and potassium in the mixture does not change the pH of the soil, but only has a beneficial effect on its biochemical composition.

Advantages and disadvantages

Phosphorus-potassium fertilizing is well accepted and absorbed by all parts of plants, that is, not only by the root system, but also by stems and foliage. It does not include chlorine and is completely safe for nature and humans, unless added randomly and in large quantities.

There are other advantages:

fertilizing activates the growth of full-fledged side shoots;
increases immunity to powdery mildew and other pests, as well as diseases;
improves sensitivity to temperature changes, especially frost, as well as changes in air humidity;
promotes long and active flowering of ornamental crops and indoor flowers;
activates root formation in seedlings;
helps retain moisture in the soil in greenhouses, which is important during the dry season;
reduces the fall of ovaries, increases their quantity and quality;
activates the absorption of vitamins and carbohydrates, which has a beneficial effect on the taste of the fruit.

Agricultural technologists and agronomists also talk about the disadvantages of monopotassium phosphate:

stops the growth of cuttings of roses and other flowers that are cut for bouquets;
slows down the growth of ornamental plants that themselves develop slowly, for example, succulents, orchids;
not compatible with potash and magnesium fertilizers;
suitable only for one-time processing, since the constituent elements are destroyed under the influence of air and sunlight;
quickly washed out after prolonged rains and active frequent watering, so regular application is required, since plantings react acutely to a lack of potassium;
activates the growth of not only vegetables, trees, bushes, but also weeds.

After being added to the soil, potassium monophosphate crystals immediately disintegrate; it is better to dissolve them in water. They are not suitable for autumn preparation of soil for wintering. Capricious and demanding of the environment. For their positive effect, humidity should be moderate and temperature not high.

During storage of potassium monophosphate, the granules should not be allowed to get wet so that they do not dissolve and lose their beneficial properties. Experts advise purchasing this fertilizer in small packages intended for single application.

Flaws

This fertilizer does not accumulate in the ground and disintegrates in a short time, because fertilizing is carried out exclusively with solutions. Experts note that adding them in solid form will not cause any harm to the plants, but there will be no benefit from it. It will simply be lost, so it is not suitable for preparing plantings in open ground in the pre-winter period.

This fertilizer is most effective in the warm season, especially if the period is moderately humid and not hot. It can also be used in greenhouses, not forgetting about regular ventilation and sufficient lighting.

Another disadvantage is that weeds love it, so the garden will have to be carefully weeded. Otherwise, the garden plot is guaranteed to become overgrown. Potassium monophosphate is hygroscopic, and when it is wet, its properties are lost. Working solutions are unstable in light and air, so it is recommended to purchase them in packages suitable for single use. The working solution is used immediately after its preparation.

This fertilizer can cause increased tillering, so its use for cut flowers is limited. Even if you have to cut the inflorescences or brushes, the cuttings will be very short in order to put them in a vase. And this makes the product’s marketability low.

This type of highly active feeding is not used for indoor plants that develop slowly or are so-called “dormant”. These include:

azaleas;
orchids;
gloxinia;
cyclamens;
dodecatheon;
all types of succulents and others.

Nitrogen Compatible

Potassium monophosphate is compatible with many other mineral and organic fertilizers. This is a universal solution if you need complex treatment of your garden and vegetable garden.

The use of monopotassium phosphate during the growing season to feed plantings is sometimes combined with the addition of nitrogenous mineral compounds. They do not conflict. On the contrary, nitrogen is needed for better absorption of phosphorus and potassium oxide from the soil.

There is just one “but” - they should not be mixed in tank mixtures and added at the same time. A break of at least 3-5 days is necessary. First, the plants are fed with a potassium-phosphorus component, and then with a nitrogen compound.

But monopotassium phosphate is not compatible with calcium and magnesium. The fertilizer must not be mixed with magnesium or calcium nitrate, as well as other fertilizers containing these substances.

For indoor and garden flowers

To achieve early flowering of garden plants, water them for the first time with a 0.05% solution of potassium monophosphate (5 g of fertilizer per 10 H2O), when they have 3-4 leaves at the rate of 3-4 liters of liquid per 1 square meter. m. During the active growing season, water with a 0.07-0.1% solution of the drug. After rain, plants are sprayed with a 0.02% solution, except for ampelous petunias, they are treated with a 0.01% solution.

Houseplants are watered twice at intervals of 2 weeks with a 0.1% solution of potassium monophosphate; as soon as buds appear, fertilizing is stopped.

The drug should be stored out of the reach of children and pets. You need to wear rubber gloves when working with fertilizer, and use a respirator when spraying. If the drug gets on the skin or eyes, they must be rinsed with plenty of water.

Rules of application

Agronomists advise treating dacha plantings with potassium monophosphate in the spring, when transplanting seedlings to a permanent bed in unprotected soil or a greenhouse, as well as during flowering and budding.

Fertilizer rates differ for different crops.

For cucumbers and tomatoes

Cucumbers are fed with monopotassium phosphate according to the following scheme:

Root fertilizing is applied for the first time 10-15 days after planting seedlings or first shoots. A few teaspoons of powder or granular substance are dissolved in a 10-liter bucket of water. This volume is enough to water 4-6 plants.
After root application, non-root application is done, but already in the fruiting phase. Dissolve 1 teaspoon of fertilizer in a bucket and spray all plantings.
The last third subcortex of cucumbers is carried out in the phase of active fruit set. To prepare the working solution you will need a bucket of water and 1 teaspoon of powder. Spray the leaves.

For the first time, it is worth testing the product on several plants. If after a few days they begin to look better and grow more actively, then you should continue in the same spirit. The concentration is reduced if, after foliar feeding, a yellowish mosaic appears on the leaves.

Instructions for use for tomatoes are almost identical to cucumber:

the first application of fertilizer is 2 weeks after planting the seedlings;
then - according to schedule several more times.

They act in a similar way when it comes to bell peppers, squash and zucchini.

For flowers

Garden and house flowers are treated with a liquid fertilizer solution leaf by leaf. It is preferable during the formation of buds, although it is possible after they have opened.

In order for garden ornamental plants to begin to bloom earlier, they are treated with a solution of 0.05%, that is, 5 grams of phosphorus-potassium fertilizer are taken per 10-liter bucket. For 1 square meter you will need 3-4 liters.

During the active growing season, take 7-10 grams of product per 10 liters.

For berry bushes and fruit trees

Cherries, pears, apple trees, raspberries, blackberries, black and red currants are watered with an aqueous concentrate with potassium monophosphate at the rate of 1 teaspoon per 10 liters. A bucket is poured under each crown, and 3-6 liters are poured under each berry bush, depending on the size.

The processing scheme could be like this:

the first work is carried out after the flower stalks fall off - watering (1 teaspoon per 10 l);
then after 14-15 days the plants are sprayed with a 0.1-0.15% solution;
the last procedure (foliar application) is carried out in September (0.1-0.15% of the substance).

With strawberries, the scheme is slightly different. It is fed with potassium in combination with phosphorus at the flowering stage once a summer.

For a standard 10-liter bucket of water, 10 grams of the drug is enough. After feeding, to prevent the berry bushes from burning, they are watered with plain water.

For potatoes, root vegetables

After hilling, the leaves of the potato tops are irrigated with an aqueous suspension with monopotassium phosphate (15 g per 10-liter bucket). The second time - after the formation of buds.

It is enough to feed potatoes and other root vegetables several times a season. Applying fertilizer activates the growth of weeds, so additional weeding is necessary.

Radishes, rutabaga, turnips, and beets are fed with a potassium-phosphorus preparation at the root 3 weeks after the first shoots. Add 20 grams of product to standard 10 liters of water. This volume is intended for 4-5 square meters.

Why aren't potatoes fed at the root? The answer is simple. After such manipulation, the root crops become deformed and become smaller.

For garlic and onions

These vegetable crops can be fed with potassium monophosphate no more than once per season. This is done in the spring, during the period of foliage growth.

1 teaspoon of fertilizer per bucket of water is enough. The volume of such root feeding covers 5 meters of square plantings.

For grapes

Fertilizing in the spring reduces the likelihood that grapes will get mildew. The phosphorus-potassium mixture also increases its resistance to powdery mildew and other diseases. Applying it at the end of summer and beginning of autumn accelerates the ripening of the clusters and increases the vine's resistance to future frosts.

Fertilizer is applied by watering or by spraying on the foliage. For 10 liters of water take 10-15 grams of powder. This concentration is suitable for both root and foliar application.

It is especially relevant if the summer was wet and rainy, when many nutrients were washed out of the soil. It is impossible to combine potassium monophosphate with magnesia or calcium compounds.

For seedlings

The use of monopotassium phosphate is allowed for young vegetable crops and flowers, but it is important to know how to do it correctly. The composition of the fertilizer is such that young plantings need it, especially after planting from cups in an open bed or in a flower garden with other plants.

Take 10 grams of fertilizer per 10-liter bucket. It is enough to spill the seedlings with this solution. But not immediately after planting in a permanent place, but after 2-3 weeks, when the main rooting occurs.

Root feeding with phosphorus-potassium fertilizer should always be carried out on damp soil, wearing safety glasses, gloves and a respirator. And spraying, also with protective equipment, only early in the morning or after sunset, so that the product does not cause burns. In this case, use a fine spray so that the liquid does not flow from the leaves in the form of drops.

It is worth adding that:

the product is quickly absorbed by the soil, allowing you to obtain a rich and tasty harvest.
it does not contain chlorine or dangerous pesticides, but plants need to be fed with it on a schedule, following the norms and taking breaks.
Fine granular potassium-phosphorus powder dissolves best in warm water.
the agricultural product rarely burns the roots and foliage if you water the plants on moist soil or spray them at 6 am or after 6 pm.

Application of potassium monophosphate fertilizer - benefits for plants

When using potassium monophosphate fertilizer, you can stimulate the growth and fruiting of vegetable plantings, berry bushes and fruit trees, and prolong the flowering of ornamental crops. This product is versatile - it can be used for both garden and indoor plants.

The main advantages of potassium monophosphate:

increases plant resistance to fungal and infectious diseases;
increases crop productivity;
strengthens the immunity of plants, helping them to easily withstand frost;
saturates dry soil with moisture;
does not affect soil acidity;
increases the number of shoots in young seedlings;
combined with pesticides, so it can be used in complex treatment.

Potassium monophosphate does not contain harmful sodium salts, chlorine and other heavy metals, so even an increased dosage of monopotassium phosphate does not cause burns to the foliage and root system.

Analogs

Potassium monophosphate can be replaced with other fertilizers. Double superphosphate and potassium nitrate are suitable analogues. They also strengthen the roots, activate the growth of green mass and fruit set, improve their taste and activate the plant’s immunity.

Wood ash can be distinguished from natural fertilizers with phosphorus and potassium. It's not worth buying. It is enough to use ash after burning dry tops, straw, sawdust, and tree branches in the fall. It is simply scattered dry over the area for planting (trees, shrubs) or used during autumn plowing.

Alternating the application of potassium monophosphate in the form of spraying and ash at the root gives excellent results throughout the season, from spring to late autumn.