Monopotassium Phosphate (MKP) 0-52-34: The Premium Water-Soluble Fertilizer

Monopotassium phosphate (MKP) is a nitrogen-free, fully water-soluble fertilizer. It supplies high levels of phosphorus and potassium in one product. Its standard grade is 0-52-34.

Importers, distributors, blenders, greenhouse growers, and large farms all ask the same questions about it. They want to know the nutrient content, the solubility, the mixing safety, the quality specification, and the supply stability.

This guide covers MKP 0-52-34 from four angles: product properties, production, agricultural use, and commercial procurement.

The word “premium” is used here in a narrow sense. It refers to measurable indicators such as assay, water-insoluble matter, impurity control, and batch-to-batch consistency. It is not a blanket promise of quality.

What Is Monopotassium Phosphate Fertilizer?

Monopotassium phosphate is a crystalline potassium phosphate salt used as a water-soluble PK fertilizer. It carries no nitrogen and no chloride in its pure chemical form.

Chemical Formula, Other Names, and Basic Properties

MKP has the chemical formula KH₂PO₄.

Attribute	Value
Chemical formula	KH₂PO₄
CAS No.	7778-77-0
Molar mass	136.09 g/mol
Appearance	White crystals or crystalline powder
Solubility in water (20 °C)	About 22.6 g per 100 mL
pH of 1% solution	About 4.4 to 4.6

The product is odorless and mildly hygroscopic. It absorbs moisture from humid air, so packaging must stay sealed. It dissolves quickly in water and forms a clear, mildly acidic solution.

MKP goes by several other names, such as monopotassium phosphate, potassium dihydrogen phosphate, and potassium phosphate monobasic. All three refer to the same compound.

What Does 0-52-34 Mean?

The three numbers are the guaranteed N-P-K grade of the fertilizer.

The 0 means the product supplies no nitrogen. The 52 means 52% available phosphate, reported as P₂O₅. The 34 means 34% soluble potash, reported as K₂O.

These numbers are oxide values, not element values. 52% P₂O₅ is not 52% phosphorus. 34% K₂O is not 34% potassium.

Nutrient	Oxide form	Elemental form
Phosphorus	52% P₂O₅	About 22.7% P
Potassium	34% K₂O	About 28.2% K

Buyers who compare offers from different regions should check which form each label uses. The oxide form is standard on fertilizer labels in most markets.

Fertilizer Grade vs. Technical Grade and Food Grade

Different grades of MKP share the same chemical formula. They do not share the same purity, impurity limits, test standards, or legal requirements.

Fertilizer-grade MKP is made for field fertigation, water-soluble blend production, and nutrient solution mixing. Technical and food grades follow separate standards and serve other industries.

Agricultural buyers should check the fertilizer registration, the label, the impurity limits, and the rules of the destination country. The product name alone is not enough to confirm the correct grade.

How Is Fertilizer-Grade MKP Produced?

Fertilizer-grade MKP is produced by reacting phosphoric acid with a suitable potassium source, then purifying and crystallizing the product.

Common Reaction and Neutralization Routes

The basic principle is a controlled neutralization. Phosphoric acid reacts with a potassium compound until the solution reaches the target ratio of potassium to phosphate.

Common potassium sources may include potassium hydroxide or potassium carbonate. The actual raw material depends on the production route of the plant.

Manufacturers use different feedstocks, equipment, and proprietary process steps. No single route should be described as the standard method for every factory.

Purification, Crystallization, Drying, and Screening

After neutralization, the solution moves through several physical steps. These include purification, evaporation, crystallization, solid-liquid separation, drying, and screening.

Purification helps control insoluble matter and part of the impurity load. Crystallization, drying, and screening then shape the crystal habit, the particle size, the flow behavior, and the dissolving performance of the finished product.

How Production Control Affects Final Quality

Process control decides whether the finished crystal meets its specification.

Raw material quality and neutralization control affect assay, pH, and impurity levels. Purification and filtration affect water-insoluble matter and mother liquor clarity. Crystallization and drying conditions affect crystal size, moisture content, and caking risk.

Steady process control keeps specifications consistent from batch to batch. That is why a high-quality MKP has to be judged on its actual specification sheet and batch test results, not on its trade name.

Why Is MKP 0-52-34 Considered a Premium Water-Soluble Fertilizer?

MKP is treated as a premium product because it delivers concentrated P and K in a clean, fully soluble form with very few unwanted ions.

High Phosphorus and Potassium with No Nitrogen

MKP supplies phosphorus and potassium together without adding nitrogen.

This suits nutrition programs that need more P and K while nitrogen input stays under control. It also lets a blender adjust N, P, and K supply separately in a formula.

Zero nitrogen is a formulation advantage. It does not mean the crop needs no nitrogen at that growth stage.

Water Solubility, pH, and Salt Index

Full water solubility matters for drip irrigation, fertigation, hydroponics, and liquid fertilizer manufacturing. Undissolved solids block filters and emitters.

MKP solutions are usually acidic. The measured pH still depends on the concentration and on the raw water. Solubility also shifts with water temperature, concentration, and other dissolved salts.

“Fully water-soluble” does not mean the stock tank concentration can rise without limit. MKP also carries a low relative salt index, often reported near 8. A low salt index still is not zero EC, and it does not remove all risk of fertilizer burn.

Low Chloride and Sodium: What the COA Should Confirm

Pure KH₂PO₄ contains no chloride and no sodium in its chemical composition.

Commercial material can still carry small amounts of both from raw materials and processing. Claims such as “low chloride” or “low sodium” should be supported by the specification sheet and the batch COA.

These figures matter most for salt-sensitive crops and for recirculating hydroponic systems, where ions build up over time.

What “Premium” Should Mean for Commercial Buyers

A premium grade should be provable on paper. Look for these markers:

• Stable P₂O₅, K₂O, or KH₂PO₄ assay that meets the guaranteed values
• Low water-insoluble matter and low moisture
• Controlled chloride, sodium, heavy metals, and other impurities
• Consistent crystal size, dissolving rate, and solution clarity
• Good flow behavior and reasonable anti-caking performance
• Complete COA, TDS, SDS, and batch traceability records

What Does MKP Fertilizer Do for Crops?

MKP acts as a nutrient source. It supplies two of the three primary macronutrients in a plant-available form.

The Role of Phosphorus in Roots and Energy Transfer

Phosphorus supports energy transfer, cell division, and the formation of new tissue inside the plant.

Adequate phosphorus nutrition supports early root establishment and general crop growth. Applying MKP does not by itself guarantee a stronger root system. Soil conditions, temperature, and existing nutrient levels all play a part.

The Role of Potassium in Water Balance and Crop Quality

Potassium supports water regulation, stomatal function, enzyme activity, and nutrient transport.

Sound potassium nutrition is linked to crop growth and quality management. It is not a direct promise of higher sugar content, better color, larger yield, or longer shelf life.

Why Zero Nitrogen Gives Growers More Control

Base fertilizer and irrigation water often already supply enough nitrogen. In that case, MKP adds P and K without pushing nitrogen higher.

This helps precision programs that manage N, P, and K separately. Zero nitrogen should not be described as a way to suppress vegetative growth, trigger flowering, or guarantee fruit set.

What MKP Cannot Supply

MKP is not a complete fertilizer.

On its own it cannot supply nitrogen, calcium, magnesium, sulfur, or the full range of essential micronutrients. A complete program still needs other fertilizer sources.

Where soil or nutrient solution already holds enough P and K, adding more MKP may bring no extra benefit.

Where and When Is MKP 0-52-34 Used?

MKP is used at crop stages and in growing systems where soluble P and K are needed and extra nitrogen is not.

Early Root Establishment and Transplanting

MKP can enter a nursery or transplant program when soil, substrate, or tissue tests show a need for phosphorus and potassium.

The rate depends on the crop type, the substrate properties, and the nutrient levels already present.

Flowering and Fruit Set

MKP is often used at stages with high P and K demand where added nitrogen is not wanted.

Its role is to supply nutrients. It is not a plant growth regulator, and it should not be presented as a way to force flowering or hold fruit.

Fruit Filling, Ripening, and Quality Management

Fruit development stages usually call for careful potassium management.

MKP can serve as the P and K source inside a full nutrition plan at that point. Results depend on the crop, the variety, the environment, the irrigation, and the overall nutrient status.

Crops and Growing Systems That Commonly Use MKP

MKP is used across many high-value crops, such as greenhouse vegetables, berries, and cut flowers.

Typical users include:

• Greenhouse vegetables, for example tomato, pepper, and cucumber
• Fruit crops, for example grapes, citrus, and berries
• Flowers and other high-value horticultural crops
• Open field, greenhouse, soilless, and hydroponic systems

MKP is not restricted to one crop or one production system.

Why Soil, Water, and Tissue Tests Come First

A fertilizer plan should start with data. That means soil or substrate testing, irrigation water analysis, and plant tissue testing.

Crop stage, yield target, climate, and local agronomic advice all shape the final rate. No single rate fits every crop and every region.

How Is MKP Fertilizer Applied?

MKP is applied through irrigation systems, foliar sprays, and manufactured water-soluble blends.

MKP for Drip Irrigation and Fertigation

The basic sequence is simple: prepare the stock solution, inject it, filter it, and flush the lines with clean water afterward.

Check the raw water first for hardness, pH, EC, and calcium and magnesium content. Then calculate the rate from the injection ratio of the equipment and the target nutrient concentration.

Avoid stock solutions that sit above the solubility limit of the product.

MKP for Greenhouses and Hydroponics

Greenhouse and hydroponic systems demand precise formulas, clear solutions, and very low insoluble matter.

Batch consistency matters here more than anywhere else, because automatic dosing and recirculating systems run on fixed settings. MKP should normally be stored and prepared in a separate tank from concentrated calcium fertilizers.

Final solution strength should follow the crop stage, the raw water, and the target EC.

MKP for Foliar Feeding

Foliar feeding is a supplement to root-zone nutrition, not a full replacement for it.

Spray concentration should follow the product label, the crop type, the leaf age, the temperature, and local advice. Avoid spraying in high heat, strong sunlight, or other conditions that raise the risk of leaf damage.

Run a small test area before any tank mix or full-scale spray.

MKP for Water-Soluble Blends and Liquid Fertilizers

Blenders and liquid fertilizer manufacturers value MKP as a clean P and K carrier.

For this use, the key checks are particle size, dissolving rate, water-insoluble matter, and batch consistency. Formulation work should verify nutrient balance, physical stability, and chemical compatibility.

The finished label and guaranteed analysis must match the fertilizer regulations of the sales market.

How to Calculate the Nutrients Supplied by MKP

The math is direct.

MKP rate × 52% = P₂O₅ supplied. MKP rate × 34% = K₂O supplied.

For elemental values, apply the oxide conversion factors: multiply P₂O₅ by 0.436 for P, and K₂O by 0.83 for K.

Always count both nutrients in the formula. Sizing the rate on phosphorus alone will leave the potassium figure unplanned, and the reverse is equally true.

How to Mix and Dissolve MKP Safely

Safe mixing depends on water temperature, dissolving order, and tank separation.

Water Temperature, Solubility, pH, and EC

Cold water lowers the concentration a stock tank can hold.

Add part of the clean water first. Then add MKP slowly while stirring. Confirm that it has fully dissolved before any other fertilizer goes in.

Check the final solution for pH, EC, cloudiness, and sediment. A low salt index alone is not proof that a concentrated solution is safe for the crop.

Why MKP and Calcium Fertilizers Need Separate Stock Tanks

Phosphate ions and calcium ions can form poorly soluble precipitates under concentrated conditions.

MKP should not go into the same concentrate tank as calcium nitrate or similar calcium fertilizers. Precipitation causes nutrient loss, filter load, and emitter blockage.

With separate tanks, both can still be injected into the same irrigation line once the water dilutes them enough.

How to Manage Magnesium and Micronutrients

Magnesium compatibility depends on the fertilizer type, the concentration, the water quality, the pH, and the mixing conditions. MKP should not be labeled as universally compatible or incompatible with all magnesium products.

Micronutrients such as Fe, Mn, Zn, and Cu should be supplied in forms suited to the target pH and water conditions. Check the compatibility data from the supplier before any concentrated mix.

Two-Tank Systems and Jar Tests

An A/B two-tank system keeps concentrated calcium apart from phosphates and sulfates. That is the basic logic behind it.

Run a jar test before any new formula enters production. Watch for precipitate, floc, cloudiness, separation, and unusual heat.

When mixing with pesticides or other inputs, follow the label requirements of every product involved.

MKP vs. Other Water-Soluble Fertilizers

The right choice depends on which second nutrient comes along with the potassium or phosphorus.

MKP vs. Water-Soluble MAP

MKP supplies phosphorus and potassium, with no nitrogen. Water-soluble MAP supplies nitrogen and phosphorus, with no potassium.

MAP may fit better when the crop needs extra nitrogen. MKP gives more room to adjust when the formula needs P and K without more N.

MKP vs. Potassium Nitrate

MKP supplies phosphorus and potassium. Potassium nitrate supplies nitrogen and potassium.

Both deliver potassium. They differ in the partner nutrient. The choice comes down to whether the program needs phosphorus or nitrogen at that point.

MKP vs. Potassium Sulfate

MKP supplies phosphorus and potassium. Potassium sulfate (SOP) supplies potassium and sulfur.

The two differ in nutrient pairing, physical form, solubility, and formulation role. Buyers should also separate standard SOP from soluble SOP grades made for fertigation.

How to Choose the Right Fertilizer Source

Product	Nutrients supplied	Typical fit
MKP	P and K	P and K needed, nitrogen controlled
Water-soluble MAP	N and P	Nitrogen and phosphorus needed together
Potassium nitrate	N and K	Nitrogen and potassium needed together
Potassium sulfate	K and S	Potassium plus sulfur needed

Base the decision on soil, substrate, water, and tissue test results. Then confirm whether the formula needs extra N, P, K, or S.

Compatibility, solubility, impurities, and cost per unit of nutrient all belong in the comparison. No single product is simply “best.”

How to Check MKP 0-52-34 Quality Before Buying

Quality is confirmed through the specification sheet, the batch COA, and sample testing.

Guaranteed Nutrient Content and KH₂PO₄ Assay

Check the P₂O₅, K₂O, and KH₂PO₄ assay figures. Confirm the test method used for each result.

Learn to separate four different numbers: the guaranteed minimum, the specification limit, the typical value, and the actual batch result. The grade “0-52-34” alone cannot rank one supplier against another.

Solubility, Insoluble Matter, Moisture, pH, and Particle Size

These five physical properties decide how the product behaves in a real system.

Solubility sets how efficiently a stock tank can be prepared. Water-insoluble matter drives filter load and emitter blockage risk. Moisture affects available content, flow, and caking. pH is a useful identity and formulation reference. Particle size and its distribution affect dosing, dissolving speed, and production throughput.

Chloride, Sodium, Heavy Metals, and Other Impurities

Acceptable limits depend on crop sensitivity, the production system, and the regulations of the destination country.

Recirculating hydroponic systems pay closer attention to sodium and other ions that accumulate. Heavy metal requirements should be verified against the import market and the end use.

Avoid absolute claims such as “zero impurities” or “100% pure” when no test data supports them.

COA, TDS, SDS, and Batch Traceability

Request the COA that matches the actual shipped batch. Check that the TDS and SDS are current versions.

Review the batch number, the production date, the test methods, and the traceability record. Confirm the fertilizer registration, labeling, and import documents required by the destination country.

Product name, grade, and specification should read the same across all commercial documents.

Sample Testing Before a Bulk Order

Inspect the sample for appearance, color, crystal condition, and caking.

Then test the dissolving speed, solution clarity, pH, and insoluble residue. Run compatibility tests with the actual production water.

For large or long-term contracts, consider third-party laboratory verification of the key parameters.

Bulk MKP Packaging, Storage, and Supply

Bulk MKP moves in moisture-proof packaging and needs dry, controlled storage.

Common Packaging Options

Common options include 25 kg lined woven bags, paper-plastic composite bags, and jumbo bags.

Pallet type, stretch wrap, shipping marks, and private label details are confirmed against customer requirements. The final packing format, net weight, and container loading follow the supplier quotation and the transport plan.

No single packing format is standard across all markets.

How to Store MKP Fertilizer

Keep the original packaging sealed.

Store in a dry, cool, well-ventilated space. Protect the product from moisture pickup, damaged bags, contamination, and long periods under heavy load.

Stack according to warehouse conditions to limit caking and bag deformation. Shelf life should follow the specific product documents rather than a general assumption.

What Bulk Buyers Should Confirm Before Ordering

Settle the commercial details before the contract, not after.

• MOQ, monthly supply capacity, and production lead time
• Packing specification, pallets, marks, and private label requirements
• Loading quantity per container, shipping mode, and delivery time
• Pre-shipment inspection, batch consistency, and third-party testing
• COA, certificate of origin, and other export documents
• The claim procedure for off-specification product or transport damage

Compare offers on landed cost and cost per unit of nutrient. Price per ton alone hides too much.

Frequently Asked Questions About MKP 0-52-34

Is Monopotassium Phosphate the Same as Potassium Phosphate?

Not exactly. “Potassium phosphate” is a broad name that can cover several different potassium phosphate salts.

MKP refers specifically to KH₂PO₄. Check the chemical name, the formula, and the CAS number when ordering.

Is MKP a Phosphate or a Phosphite?

MKP is a phosphate fertilizer, not a phosphite.

The two differ in chemical form, behavior in the plant, and regulatory classification. They are not interchangeable.

Can MKP Be Mixed with Calcium Nitrate?

Not in the same concentrate tank.

Use an A/B two-tank system and inject each into the irrigation line after enough dilution. Run a compatibility test before any new formula goes into production.

Does MKP Lower Irrigation Water or Soil pH?

MKP solutions are usually acidic and can influence nutrient solution pH.

The actual change depends on the rate, the water volume, the raw water alkalinity, and the buffering capacity. MKP is not a general-purpose acidifier for every soil and water condition.

Is MKP a Complete Fertilizer?

No.

MKP supplies only phosphorus and potassium. It cannot cover every essential nutrient, so it belongs inside a complete fertilizer or nutrient solution program.

Is MKP Suitable for Hydroponics?

Fertilizer-grade soluble MKP can be used in professional hydroponic nutrient solutions.

Confirm the purity, the insoluble matter, the impurity profile, and the grade first. Calculate the rate from the full nutrient formula.

Is MKP Allowed in Organic Farming?

The chemical name alone does not answer this.

Approval depends on the raw material source, the production method, the certifying body, and local organic standards. Check the certification documents for the specific product and the target market.

How Should Bulk MKP Fertilizer Be Stored?

Keep it sealed, dry, and protected from bag damage.

Store in a dry, well-ventilated warehouse. Follow the SDS, the product label, and the storage instructions from the supplier.

Conclusion: Choose MKP 0-52-34 by Specification and Application Fit

MKP 0-52-34 earns its place where precise phosphorus and potassium supply matters most, such as fertigation programs, hydroponic systems, and professional water-soluble blends.

The premium label only holds up when the paperwork supports it. Assay, solubility, insoluble matter, impurity levels, and batch consistency are the figures that prove it.

Before ordering, check the agricultural fit, the mixing requirements, the COA, the packaging, and the long-term supply capability of the manufacturer.

SUMEC Chemical supplies fertilizer-grade MKP to importers, distributors, and blenders worldwide. Visit our MKP product page to request a specification sheet, a sample, a batch COA, or a bulk quotation.

Grade, origin, packaging, MOQ, and availability are confirmed in the final commercial offer.