Synthetic ammonium sulphate fertilizers are white crystals, such as those made from coking or other petrochemical production by-products, with cyan, brown or light yellow. The content of ammonium sulphate is 20.5-21% and contains a very small amount of free acid. It is easily soluble in water and has low hygroscopicity, but it can also absorb moisture and agglomerate in rainy seasons, which will corrode the packaging bag. Pay attention to ventilation and dryness during storage. Ammonium sulphate is stable at room temperature, but when 4 alkaline substances act, it also releases ammonia gas like all ammonium nitrogen fertilizers.
After ammonium sulphate is applied to the soil, it will gradually increase the acidity of the soil through the selective absorption of crops, so ammonium sulphate is the same as physiological acid fertilizer. Ammonium sulphate is suitable for general soil and prepared crops, and smells of ammonium-loving crops. It can be used as base fertilizer, top dressing and seed fertilizer. For compulsive fertilizer, it is more economical and effective to apply a large amount of nutrients to the soil near the root system during the first few days of crop growth. However, it must be applied when there is no water droplets on the stem and leaf surface to avoid damage to the crop. For rice, it should be applied in depth or combined with cultivating fields to avoid the loss of chlorine due to nitrification and denitrification. The amount of ammonium sulphate as seed fertilizer must be small, generally 10 kg per mu, mixed with 5-10 times decomposed organic fertilizer or fertile soil, be careful not to contact with seeds. When transplanting rice seedlings, 5-10 catties of ammonium sulphate can be used per acre, combined with decomposed organic fertilizer, superphosphate, etc., to make a thin slurry, which is used to dip the roots of the seedlings, and the effect is very good.
In acidic soils, ammonium sulphate should be used in conjunction with farm manure, and should be used in conjunction with alkaline fertilizers such as calcium magnesium phosphate fertilizer and lime (not mixed application) to prevent soil acidity from increasing.
The application of ammonium sulphate fertilizer in the paddy field will produce hydrogen sulfide, which will make the rice roots black, which is toxic to the rice, especially when the dosage is large or applied in the old retting field, this poison is more likely to occur. Use turtles and combine necessary measures such as cultivating and roasting fields.