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Writer's pictureAntonia Z

Monopotassium phosphate - High-efficiency phosphorus-potassium compound fertilizer


1. Monopotassium phosphate (with 52% P2O5 and 34% K2O content) has low hygroscopicity, good physical properties, and is easily soluxble in water. At 20°C, 22.2g of monopotassium phosphate can dissolve in every 100ml of water (i.e., 222g/L), and its aqueous solution is slightly acidic (the pH of a 1% monopotassium phosphate solution is around 4.6).

 

2. Monopotassium phosphate is a very common foliar fertilizer, a high-concentration, high-quality, chlorine-free phosphorus-potassium fertilizer with extremely low salt content and high nutrient content, suitable for a variety of crops. It not only promotes fruit expansion and color change, enhances crop metabolism but also improves crop rooting, frost resistance, and stress resistance, known as the "universal fertilizer."

 

3. Monopotassium phosphate is suitable for any soil and crop, especially for regions and crops that lack both phosphorus and potassium nutrients, mainly used for foliar feeding, seed soaking, and seed dressing. When used, it is divided into three key periods: flower bud differentiation period, fruit swelling period, and coloring period. High-quality monopotassium phosphate has a high absorption rate when sprayed on leaves, with fast uptake starting 30 minutes after spraying, allowing direct absorption by the crops, showing quick and clear effects.

 

Specific Functions of Monopotassium Phosphate:

 

1.Promotes Nitrogen and Phosphorus Absorption: Monopotassium phosphate can promote the absorption of nitrogen and phosphorus by crops, quickly replenish phosphorus and potassium, improve crop yield and grain weight, and have a unique effect during special physiological periods of the crops.

 

2.Enhances Photosynthesis: Potassium element boosts photosynthesis in crop growth, accelerating the manufacture and transformation of nutrients.

 

3.Improves Crop Resistance: Monopotassium phosphate enhances the resistance of crops to adverse conditions, such as drought, hot and dry winds, flooding, frost, injury healing, and pathogen infection.

 

4.Enhances Fruit Quality: Application during the fruit swelling period can protect and strengthen the fruit, promote fruit expansion, improve fruit quality, enhance coloring, and improve taste.

 

5.Regulates Plant Growth: Monopotassium phosphate acts as a regulator, promoting flower bud differentiation, increasing the number of flowers, ensuring robust flower buds and blooms, improving fruit setting, and effectively promoting the growth and development of the root system.

 

Mixing Recommendations for Monopotassium Phosphate:

 

It can be mixed with nitrogen fertilizers, micronutrient fertilizers, and certain pesticides, saving time and labor while enhancing the effectiveness of both fertilizers and pesticides. In fields lacking nitrogen, phosphorus, and potassium, mixing monopotassium phosphate with these fertilizers is common, with an ideal urea solution concentration of 1% to 2%.

 

It can be mixed with boron fertilizers. For crops that are boron-deficient or show significant improvement with boron, mixing monopotassium phosphate with boron fertilizer can significantly increase crop yields. The concentration of boron fertilizer should be maintained between 0.05% and 0.1%.

 

It can be mixed with certain pesticides, such as imidacloprid, chlorpyrifos, and synthetic pyrethroids. It can also be mixed with plant growth regulators, such as naphthaleneacetic acid and chlormequat chloride, to enhance plant growth and health.

 

Eight Prohibitions for Using Monopotassium Phosphate:

 

1. Do not mix with alkaline products: The pH of a 1% monopotassium phosphate solution is around 4.6, which is slightly acidic. Mixing it with alkaline fertilizers and pesticides can cause chemical reactions, leading to flocculation, precipitation, discoloration, heating, and bubble formation, which can deactivate monopotassium phosphate.

 

2. Do not mix with products containing carbonate ions (CO3-) because the carbonate ions react with the hydrogen ions in monopotassium phosphate to produce carbon dioxide (CO2) gas, such as potassium carbonate, ammonium carbonate, sodium bicarbonate, etc.

 

3. Do not mix with products containing copper ions. Monopotassium phosphate should not be mixed with copper hydroxide, basic copper sulfate, calcium copper sulfate, cuprous oxide, copper complexes, or quinolinic copper, as free copper ions can react with phosphate ions to form flocculation and precipitation.

 

4. Do not mix with free-state micronutrients (calcium, magnesium, zinc, iron) in their inorganic salt form, as they should be used in their chelated (EDTA) form, which does not react with monopotassium phosphate and is more stable, preventing the formation of free metal ions.

 

5. Do not overuse in the early stages of growth, as potassium can compete with magnesium and calcium ions, affecting their absorption and hindering cell growth, which can significantly impact later production. Therefore, it's not recommended to use monopotassium phosphate before the flowering stage in vegetables and legumes to avoid damaging the plants or causing flower and pod drop. Early use in soybeans can lead to reduced yields.

 

6. Do not replace base fertilizers with monopotassium phosphate, as its high solubility and quick dissolution in water can lead to leaching when buried in the soil, making its effect short-lived. Base fertilization should still rely on compound fertilizers or slow-release fertilizers. Monopotassium phosphate's solubility and fast action make it suitable for critical periods like bud differentiation, but it can also be applied via root drenching.

 

7. Avoid using in high temperatures and concentrations, as high temperatures can increase the concentration of monopotassium phosphate solutions, causing fertilizer burn. High concentrations can also lead to leaf scorch and root burn. Application times should avoid midday heat, preferably before 10 a.m. or after 4 p.m. High-concentration foliar applications are prohibited during the hot season.

 

8. Do not mix oil emulsions before monopotassium phosphate, as mixing with oil-based pesticides should add the oil last to avoid affecting the dissolution of monopotassium phosphate. If oil is added first without diluting again, it can encapsulate monopotassium phosphate particles. Therefore, it's essential to dissolve powders and granules first before adding oil-based products.

 

Supplementary Common Fertilizer Classifications:

 

1. Based on chemical properties, fertilizers can be categorized into acidic, alkaline, and neutral fertilizers.

 

2. Based on the nutrient availability or supply rate, fertilizers can be divided into fast-release, slow-release, long-lasting, and controlled-release fertilizers.

 

3. Based on the type and quantity of nutrients, fertilizers can be classified into single-nutrient fertilizers (nitrogen, phosphorus, or potassium), compound fertilizers, and mixed fertilizers.

 

4, Based on the nutrients contained, fertilizers can be categorized into nitrogen, phosphorus, potassium, magnesium, calcium, manganese, boron, sulfur, copper, iron, molybdenum, zinc, etc. These fertilizers are further divided into macronutrient and micronutrient fertilizers based on the quantity of nutrients required by crops.




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