Black alum is used in agriculture as a soil pH improver and soil pH regulator. Used to neutralize soil acidity and alkalinity, widely used in large-scale farms, tobacco cultivation, etc. It has a wide range of applications in agriculture and can be used as herbicides and insecticides. Applying it to the soil before breeding can prevent fruit and vegetable pests and diseases and inhibit weed growth in the field. It can also prevent and control the decay and infestation of fruit tree bark. Applying agricultural black alum is also beneficial for the synthesis of chlorophyll during photosynthesis in crop leaves.
[Alias]Green alum, iron alum, green alum
Molecular formulaFeSO4·7H2O
Molecular weight278.01
【 Characteristics 】Green monoclinic or rhombohedral crystals. Easy to dissolve in water, insoluble in alcohol. Odorless.
[Proportion]1.898g/cm³When the temperature rises to 90 ℃, 6 crystal waters are lost, and at 300 ℃, all crystal waters are lost, resulting in a white anhydrous substance. It absorbs moisture in humid air and is oxidized by the air to a yellow brown or rust color. It can weather in dry air, turning into a white powder on the surface, and then oxidized by air to a yellow brown or rust color.
[Purpose]Mainly used in agriculture to treat wheat smut and prevent apple and pear scab disease. The chemical industry is mainly used to manufacture pigments such as iron oxide red and indigo. Used as a blood supplement in medicine and as a water purifying agent in tap water. It has a certain disease prevention and sterilization effect, but no insecticidal effect.

When the orchard is deficient in iron, the veins of young leaves first lose their green color and turn yellow, while the veins remain green. In severe cases, the entire new leaf turns yellow white and is prone to shedding, resulting in shoot withering. Spray 0.1% to 0.2% lemon iron or 0.2% to 0.8% Baike brand fruit tree black alum solution every 5-7 days after the germination of fruit tree leaves, for a total of 2-3 sprays, with good results.