The main types of potash fertilizers on the market are potassium Nitrate (NOP), monopotassium phosphate (MKP), potassium chloride (MOP), and potassium sulfate (SOP). Each has its unique characteristics and usage methods. Understanding their differences is key to making the best use of them. Let's take a closer look at these common potash fertilizers.
1. Potassium Nitrate - NOP
Potassium nitrate is an efficient nitrogen-potassium fertilizer, containing 13.5% nitrate nitrogen and 46% potassium. It is typically used during the fruit enlargement period but should not be used during the fruit coloration period because its nitrogen content can cause regreening, affecting the harvest time. Therefore, during the coloration period, it should be replaced with potassium sulfate to avoid using one type of fertilizer throughout the entire growth period.
2. Monopotassium Phosphate - MKP
Monopotassium phosphate contains 52% phosphorus and 34% potassium. It is a chemically neutral and physiologically neutral fertilizer with good water solubility. It is generally used before and after flowering to promote root growth and flower bud differentiation, providing energy for flowering and fruit setting. During the fruit coloration period, it can enhance color and increase sweetness. After fruit harvesting, it can promote the ripening of branches and increase woodiness.
Many people ask which is better, potassium nitrate or monopotassium phosphate? - The answer depends on the usage period and needs.
Potassium nitrate is a nitrogen-potassium compound fertilizer, while monopotassium phosphate is a phosphorus-potassium compound fertilizer. Nitrate nitrogen in potassium nitrate is easily washed away by rain, so it is not recommended for use in paddy fields. Use potassium nitrate when crops need more nitrogen and monopotassium phosphate when they need more phosphorus. Use potassium nitrate during the enlargement period and monopotassium phosphate during the coloration period.
Both fertilizers are quick-acting and more expensive than regular potash fertilizers, so they are not recommended as base fertilizers, especially potassium nitrate. They are suitable for top dressing or foliar application and can be mixed for better results if conditions allow.
3. Potassium Chloride - MOP
Potassium chloride appears as white or light-yellow crystals and can be red if it contains iron salts. It is highly soluble in water and is a high-concentration, quick-acting potash fertilizer. It can be used as a base fertilizer or top dressing, with an application rate of 8-10 kg per mu for base fertilizer and 5-7 kg per mu for top dressing. The foliar spray concentration should be 0.5%-1%.
Potassium chloride has a narrower range of applications compared to potassium sulfate. Many crops, such as lettuce, beans, tobacco, yams, watermelon, bananas, and cherries, are sensitive to chlorine and should not be fertilized with potassium chloride. Using potassium chloride can hinder the conversion of sugars into starch, reducing sugar content. Additionally, potassium chloride is not suitable for saline-alkali soils but is beneficial for fiber crops like hemp, promoting photosynthesis and fiber formation.
4. Potassium Sulfate - SOP
Potassium sulfate appears as white or colored crystals or granules, theoretically containing 54% potassium, but generally 50%. It is chemically neutral and physiologically acidic with good water solubility, low hygroscopicity, and does not easily clump during storage.
It is suitable for all types of crops and can be used as a base fertilizer, top dressing, and foliar fertilizer. The application rate is 10-12 kg per mu for base fertilizer, 5-7 kg per mu for top dressing, and a foliar spray concentration of 0.5%-1%. Potassium is generally absorbed by the soil and does not easily leach, but in sandy soils with poor fertilizer retention, "small doses, multiple applications" should be adopted. Potassium sulfate is most effective on potassium-loving crops like potatoes and melons, but long-term use can exacerbate soil acidification. It is best used from the fruit coloration stage to maturity to enhance color and sweetness. It is important to note that soil acidification, often caused by long-term use of potassium sulfate, is a primary reason for manganese toxicity in many fruit-growing regions.
Comentarios