1. Potassium nitrate: it contains 13.5% of nitrate nitrogen and 46% of potassium. It is a chemical neutral and physiological neutral fertilizer with good water solubility. Long term application will not lead to soil acidification. It is suitable for the young fruit from the expansion stage to the early coloring stage, and can promote the expansion of pulp cells. Because it contains nitrate nitrogen, it is not recommended to use in the later stage of coloring, which is easy to cause green.
2. Potassium dihydrogen phosphate: it contains 52% phosphorus and 34% potassium. It is a chemical neutral and physiological neutral fertilizer with good water solubility. Generally, before and after flowering, it can be used to promote root germination and flower bud differentiation, provide energy for flowering and fruit setting; use in coloring period can promote powder coloring and increase fruit sweetness; use after fruit picking can promote branch aging and improve fruit lignification.
Many people ask, potassium nitrate and potassium dihydrogen phosphate, which is better?
In fact, there's no better way to say that. The key is how to use them. They both contain different elements.
Potassium nitrate is a binary compound fertilizer of nitrogen and potassium, and potassium dihydrogen phosphate is a binary compound fertilizer of phosphorus and potassium. Therefore, different products should be adopted according to different periods.
Nitrate nitrogen in potassium nitrate is easily lost by rain, so it is generally not recommended to use in paddy field.
As for potassium nitrate and potassium dihydrogen phosphate, it can be understood that when the amount of nitrogen used for crop growth is large, potassium nitrate is used; when the amount of phosphorus needed for crop growth is large, potassium dihydrogen phosphate is used.
Potassium nitrate was used in the expansion stage and potassium dihydrogen phosphate was used in the coloring stage.
Potassium nitrate was used in normal growth period and potassium dihydrogen phosphate was used in flowering and fruiting period.
Strictly speaking, these two products cannot be regarded as pure potash fertilizer. Even potassium dihydrogen phosphate is classified as phosphate fertilizer in many classifications.
These two kinds of fertilizers are quick acting fertilizers, and the market price is higher than that of ordinary potash. Therefore, it is not recommended to use them as base fertilizers, especially potassium nitrate. They are used for topdressing or extra root fertilization.
If there are conditions, you can use the two together, it will be better. Many high-end water-soluble fertilizer materials will use these two things. Some friends said that the water-soluble fertilizer using potassium nitrate and potassium dihydrogen phosphate as raw materials should be the conscience product of the industry.
The most important point is that the quality of these two products made in China can only be achieved by regular manufacturers, and there is no need to import them.
Finally, I'd like to add a potassium sulfate:
Potassium sulfate: theoretically, it contains 54% of potassium, generally 50%; it is a chemical neutral and physiological acid fertilizer with good water solubility, but it will aggravate soil acidification if it is used for a long time, which is suitable for the later stage of grape coloring to the ripening stage of fruit, so as to promote the pink coloring of fruit and increase the sweetness of fruit.