What kind of fertilizer is Calcium phosphate monobasic? How should it be applied?

Superphosphate is often called ordinary superphosphate, or simply ordinary calcium. It is a commonly used variety of phosphate fertilizer in my country. However, for many farmers, there are still questions about how to use superphosphate correctly. Let's take a look at the correct use of superphosphate.

What is superphosphate?

Superphosphate is a chemical acid fertilizer suitable for application on neutral, slightly alkaline and alkaline soils. Since superphosphate contains a large amount of gypsum and free acid, it has the effect of improving soil when applied on alkaline soil. Superphosphate is suitable for all kinds of crops and can be used as base fertilizer, seed fertilizer, topdressing and foliar topdressing. When making seed fertilizer, avoid direct contact with seeds.

Correct use of superphosphate

1. As base fertilizer

Superphosphate has low mobility in the soil. Even within 2-3 months after superphosphate application, more than 90% of the phosphate fertilizer is still concentrated within 0.5 cm of the fertilization point and 0-5 cm deep. After superphosphate comes into contact with the soil, it is easily fixed by the soil. Therefore, it should be promoted to apply it in a concentrated manner near the seeds or crop roots, which can reduce the chemical fixation of phosphorus and help improve the utilization rate of phosphorus fertilizer.

Mixing superphosphate with organic fertilizer as base fertilizer is an effective measure to reduce phosphorus fixation and improve fertilizer efficiency. The organic colloids and crude organic matter in organic fertilizers can play a protective role in preventing water-soluble phosphoric acid from contacting iron, aluminum, calcium and other ions. In addition, organic fertilizers can form a variety of organic acids during the decomposition process. On the one hand, they have a strong ability to complex iron, aluminum, calcium and other ions, making them more stable organic complexes to reduce the chemical fixation of phosphorus, and at the same time promote the dissolution and release of insoluble phosphates. When superphosphate is mixed with organic fertilizer, it is more appropriate to mix the two in a ratio of 1:4.

When superphosphate is used as base fertilizer, 15-25 kg per mu is used. If the amount is large, it can be applied in layers, that is, deep application when turning the soil and shallow application when harrowing the soil. If the amount of fertilizer is small, it can be applied in a shallow layer (9-15 cm deep) before sowing, which is conducive to root absorption during the seedling stage.

2. Topdressing

Superphosphate can be used as early topdressing. The reasonable application method is to dig a ditch or hole at a certain distance from the plant (6-10 cm), generally about 10 cm deep, apply superphosphate in the ditch, and cover it with soil after application. Note that it should not be mixed with alkaline substances such as wood ash, lime nitrogen, lime, etc.

3. Foliar topdressing

Superphosphate has a good effect as foliar topdressing. Foliar topdressing can not only avoid the fixation of phosphorus in the soil, but also saves dosage and has a fast fertilizer effect. Especially in the late growth period of crops, when the root's ability to absorb nutrients is weakened, foliar topdressing of phosphorus fertilizer can timely make up for the lack of root absorption of phosphorus. Before spraying, soak superphosphate in 10 times water, stir and filter to clarify, take the supernatant and dilute it, spray it in the early morning or evening when there is no water, the spraying concentration for monocotyledonous plants is 1%-3%, and the spraying concentration for dicotyledonous plants is 0.5%-1.0%, 50-10 kg of aqueous solution per mu, spray once every 5-7 days, and can be sprayed 2-3 times.