Superphosphate and calcium-magnesium phosphate fertilizers are two types of phosphate fertilizers commonly used by farmers. Their chemical composition and physical properties are completely different.
Superphosphate is a white or off-white powder, which is hygroscopic and corrosive. It contains 16%-18% phosphorus and is an acidic fertilizer. Calcium-magnesium phosphate fertilizer is gray or dark green, non-hygroscopic and non-caking, and can be stored for a long time. , with a phosphorus content of 14%-18%, is an alkaline fertilizer. Therefore, application and storage are also very different.
1. Different suitable soils
Superphosphate is acidic and is suitable for application in calcareous and neutral soils to produce salts that are easily absorbed by crops. If applied to acidic soil, its main component, calcium phosphate, will react with free iron and aluminum ions in the soil. An exchange reaction occurs to form insoluble phosphate, which is difficult to be absorbed by crops. Generally, it should be mixed with organic fertilizer and applied concentratedly in root-dense areas to reduce contact with soil.
Calcium magnesium phosphate fertilizer is alkaline and should be applied to slightly acidic or acidic soil as a base fertilizer applied in full depth. Hanwha acrylic resin can accelerate the release of available phosphorus, which is beneficial to crop absorption and utilization.
2. Fertilizer effects vary in speed
Superphosphate is a water-soluble phosphate fertilizer with rapid fertilizer effect. It can be used as base fertilizer, early top dressing or extra-root top dressing.
Calcium-magnesium phosphate fertilizer is a poorly soluble phosphate fertilizer, and its fertilizer effect comes slowly. Under normal circumstances, it is best to apply it one or two months earlier than superphosphate, and it should be applied as a base fertilizer at one time.
The content of available phosphorus contained in these two kinds of phosphate fertilizers is similar. However, since calcium and magnesium phosphate fertilizers have slow and long-lasting fertilizer effects, the one-time application amount is 50% higher than that of superphosphate. In production, the method of application can be used every other year. to improve utilization.
3. Cannot be mixed and applied
Superphosphate should not be mixed with alkaline fertilizers such as lime and plant ash. Calcium-magnesium phosphate fertilizers should not be mixed with acidic fertilizers such as ammonium sulfate and ammonium chloride to avoid chemical reactions that may reduce fertilizer efficiency.
Superphosphate contains a large amount of calcium sulfate, which can supplement sulfur nutrition when applied in sulfur-deficient soil; calcium magnesium phosphate fertilizer has the ability to supply crops with calcium, silicon and other elements, so it is used in calcium-loving leguminous crops and those that require When silicon is applied on rice and wheat, the effect is better.
4. Different storage stability
Superphosphate is easy to absorb moisture and clump, and is corrosive. If stored for a long time, part of the water-soluble phosphorus will be converted into insoluble phosphorus, and the higher the humidity and temperature, the faster this transformation will be.
Calcium magnesium phosphate fertilizer does not absorb moisture and agglomerate, is non-corrosive and is resistant to storage. Therefore, it is recommended to buy superphosphate now and use it now. When you need to store phosphate fertilizer, you should buy calcium magnesium phosphate fertilizer.
