Superphosphate direct seed dressing. Superphosphate contains 3.5% to 5% free acid, which is highly corrosive. If superphosphate is used for direct seed dressing, especially if it is stored for a long time after seed dressing, it will easily corrode seeds and reduce seed germination rate and emergence rate. . Therefore, superphosphate is used as a seed fertilizer, the best form or hole is applied in the sowing ditch, and the soil is used to separate the fertilizer from the seed.
Diammonium phosphate is applied with water. After diammonium phosphate is applied with water, it is very easy to cause the loss of nitrogen in the volatilization. Phosphorus only stays on the surface and is not easily sent to the rhizosphere of the crop. Crops have neither nitrogen nor phosphorus, and diammonium phosphate is not equal to white. Therefore, the diammonium phosphate should promote the basic application. If it is used as top dressing, it should be applied early, deep in the ditch, covered with soil after application, and it is generally required that the ditch is about 10 cm deep.
The shallow application of ammonium bicarbonate and the tight cover soil resulted in low fertilizer utilization. Therefore, the application of ammonium bicarbonate should be deeply applied to the soil and timely watering, so that ammonia is fully absorbed by the soil to improve fertilizer efficiency. Tests have shown that the deep application of ammonium bicarbonate can increase the utilization rate by 10% to 30%.
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