The synthetic ammonium sulfate fertilizer is white crystal. If it is made from coking or other by-products of petrochemical production, it is green, brown or yellowish. The content of ammonium sulfate is 20-21%, which contains a very small amount of free acid. It is easy to dissolve in water and has little hygroscopicity, but it can also absorb moisture and agglomerate in rainy season, corrode packaging bags, and pay attention to ventilation and drying during storage. Ammonium sulfate is stable at room temperature, but when 4 alkalis act, ammonia gas will be released, just like all ammonium nitrogen fertilizers. When ammonium sulfate is applied to soil, the soil acidity will increase slowly by selective absorption of crops, so ammonium sulfate is the same as physiological acidic fertilizer.

Ammonium sulfate is suitable for general soils and reserve crops, and is best smelled in ammonium-preferred crops. It can be used as base fertilizer, topdressing fertilizer and seed fertilizer. It is more economical and effective to apply a large amount of nutrients to the soil near the root system in the first few days of crop growth, but attention must be paid to the application when there are no water droplets on the stem and leaf surface in order to avoid harming the crops. It should be applied deep or in combination with tillage field in order to avoid chlorine loss caused by nitrification and denitrification.

The amount of ammonium sulfate used as seed fertilizer must be small, usually 10 kg per mu, mixed with 5-10 times matured organic fertilizer or fertilizer, pay attention not to contact with seeds. When transplanting rice seedlings, 5-l0 kg of ammonium sulphate per mu can be used to mix with decomposed organic fertilizer and superphosphate to form a slurry, which can be used to dip the roots of rice seedlings. The effect is very good.

In acidic soil, ammonium sulfate should be applied in combination with farm manure, calcium magnesium phosphate fertilizer, lime and other alkaline fertilizers (not mixed application) in order to avoid the increase of soil acidity.

The application of ammonium sulfate fertilizer in paddy field will produce hydrogen sulfide, which will blacken the root of rice and be toxic to rice. Especially when the amount of ammonium sulfate fertilizer is large or applied in old rice field, this kind of toxicity is more likely to occur. Therefore, when applying ammonium sulfate fertilizer in paddy field, attention should be paid to using turtles and combining with necessary measures such as cultivating and roasting fields.

Above are the points needing attention when ammonium sulfate fertilizer is applied.