Superphosphate is also called general calcium phosphate, or general calcium for short. It is the first kind of phosphate fertilizer produced in the world, and it is also a kind of phosphate fertilizer widely used in our country. The effective phosphorus content of superphosphate varies greatly, generally between 12% and 21%. Pure superphosphate is dark gray or off-white powder, slightly sour, easy to absorb moisture, easy to agglomerate, and corrosive. After being dissolved in water (the insoluble part is gypsum, accounting for about 40% to 50%), it becomes acidic quick-acting phosphate fertilizer.
Superphosphate is suitable for various crops and various soils. It can be applied to neutral, calcareous phosphorus-deficient soil to prevent fixation. It can be used as base fertilizer, top dressing, seed fertilizer and root top dressing.
When superphosphate is used as the base fertilizer, the application rate per mu can be about 50kg per mu for the soil lacking available phosphorus, and half of it is evenly sprinkled before the cultivated land, combined with the cultivated land as the base fertilizer. Before planting, sprinkle the other half evenly, combine with the ground preparation and apply shallowly into the soil to achieve layered application of phosphorus. In this way, the fertilizer effect of superphosphate is better, and the utilization rate of its effective ingredients is also high. If mixed with organic fertilizer as base fertilizer, the application rate of superphosphate per mu should be about 20-25kg. Concentrated application methods such as ditch application and acupoint application can also be used.