Potassium chloride and potassium sulfate are both potash fertilizers, what is the difference? Which is better?
Potassium is one of the three major elements that plants need, and the role of potassium fertilizer is very important, especially tuber crops such as sweet potatoes, radishes, and potatoes, which are inseparable from potassium. On cotton, potassium fertilizers are mainly potassium chloride, potassium sulfate and potassium dihydrogen phosphate, but potassium dihydrogen phosphate is generally used as a phosphorus-potassium compound fertilizer, which is usually used for foliar spraying.
This article mainly talks about potassium chloride and potassium sulfate, both of which are potassium fertilizers. What are the differences between them?
1. The difference between potassium chloride and potassium sulfate
（1）Similarities between the two potash fertilizers
Both potassium chloride and potassium sulfate can be dissolved in water and can be directly absorbed and utilized by crops. At the same time, they are all physiologically acidic fertilizers, so they should not be applied alone for a long time, especially in acidic soil, otherwise it will cause soil acidification and hardening. Therefore, it is best to use it with alkaline fertilizers (calcium magnesium phosphate fertilizer, lime). In addition, they are all inorganic fertilizers, and the potassium ions separated after application can be adsorbed by soil organic matter, but in soils lacking organic matter, such as sandy soils, potassium ions are easily lost with water, so they should be applied in conjunction with organic fertilizers, and Apply an appropriate amount of lime to avoid affecting the structure and properties of the soil.
（2）The difference between the two potash fertilizers
Potassium Chloride: Appearance is white or light yellow crystals, sometimes containing iron salts that are red. It is easily soluble in water and is a high-concentration quick-acting potassium fertilizer. It is hygroscopic and easily agglomerated by moisture, but the agglomeration does not affect the use effect. Potassium chloride contains high potassium oxide, generally 50%-60%, can be dissolved in water, and has quick effect after application.
Potassium sulfate: white or off-white crystals, potassium content of about 50%, sulfur content of about 18%, easily soluble in water, low hygroscopicity, not easy to agglomerate, easy to apply, is a good water-soluble quick-acting potassium fertilizer.
The cost of potassium sulfate is slightly higher than that of potassium chloride, but from the perspective of nutrient content, the potassium content of potassium chloride is about 10% higher than that of potassium sulfate. At the same temperature, the solubility of potassium chloride is significantly higher than that of potassium sulfate. Taking 10 °C as an example, 100 grams of water can dissolve 31 grams of potassium chloride, while potassium sulfate only dissolves 10 grams. Under the same conditions, potassium chloride is significantly faster than potassium sulfate, only 11.2 minutes, the solubility of chloride can reach 90%, and the time is only 1/3 of potassium sulfate.
Therefore, there is also a drawback in the application of potassium sulfate. When the application area is large, the amount of fertilizer used is also large, and the dissolution rate is slow. Especially in Xinjiang, the water quality is hard. The application of potassium sulfate in cotton fields may cause calcium sulfate to precipitate and block the dripper. .
2. the difference in the scope of application
（1）Apply crops
Potassium chloride contains chloride ions, and its application in ramie and cotton fields can improve yield and fiber quality; however, when applied to chlorine-avoiding crops that are particularly sensitive to chlorine, such as tea tree, tobacco, and ginger, the aroma will be reduced, and the flammability of tobacco will also be reduced. Deterioration; chloride ions will reduce the yield and quality of chlorine-avoiding crops such as beets, potatoes, sweet potatoes, and grapes. If these crops must use potassium chloride, it is best to compost them with organic fertilizers as base fertilizers, or apply them as early as possible. Potassium sulfate does not contain chlorine, and its application range is wider than that of potassium chloride. It is used for all chlorine-avoiding crops such as tobacco, sweet potato, sugarcane, and cruciferous sulfur-loving crops, and the effect is better than that of potassium chloride.
（2） Apply soil
Potassium sulfate should not be applied to the land that is not decomposed, in order to prevent the reduction of sulfide to hydrogen sulfide and poison the root system of crops. Therefore, this type of plot is suitable for the application of potassium chloride, and the chloride ions in the potassium chloride are leached to the lower soil layer, which can avoid its adverse effects on crops. In addition, chloride ions have a special inhibitory effect on the nitrifying bacteria in the soil, which can reduce the loss of denitrification caused by nitrification and denitrification of ammonium nitrogen fertilizer. However, for the plots with heavier salinity and alkali, it is not suitable to apply potassium chloride for a long time, otherwise it will make the salinity and alkali heavier.
（3）Application method
In addition to being used as base fertilizer and top dressing, potassium sulfate can also be used as seed fertilizer and top dressing outside the roots. The amount of base fertilizer is generally 12-15 kg per mu, the amount of top dressing is generally 6-8 kg per mu, the amount of seed fertilizer is generally 2-3 kg per mu, and the concentration of foliar spray fertilizer is 0.5%-2%; and potassium chloride can only be used. It is used as base fertilizer and top-dressing fertilizer, and cannot be used as seed fertilizer and top-dressing fertilizer outside the roots, because chloride ions have a burning effect on seed germination and young stems and leaves. The amount of base fertilizer is generally 15-20 kg per mu, and the amount of top dressing is generally 8-10 kg per mu.
In short, fertilizer is the key to high yield and good harvest. Whether it is planting by yourself or instructing others to plant, you must use the correct method of fertilizing and fertilizing.
