The distribution of soil pH in China is generally acid in the South and alkali in the north, which directly affects the growth of plants. Ferrous sulfate is an acidic compound, which can adjust the acid-base balance of alkaline soil. If there is a lack of iron in the soil, the growing plants will appear yellow leaves, premature aging, and fruit quality and yield decline. The lack of iron in soil will lead to poor cell mobility in plants. The causes of soil acid-base imbalance are as follows: 1. Environmental pollution makes the pH concentration in soil too high, which leads to the hydrolysis and precipitation of iron in soil and reduces the availability of iron in soil; 2. Excessive bicarbonate in soil makes iron inactivate in plants; 3. Excessive manganese, zinc, phosphorus and other elements in the soil may also cause iron deficiency in the soil; 4. Unreasonable fertilization and the formation of sandy soil lead to iron deficiency.

Ferrous sulfate, as an acid iron fertilizer, can not only adjust the high alkalinity of alkaline soil to neutral, but also adjust acid plants to acid soil to promote the formation of chlorophyll and supplement iron for plants.

Ferrous sulfate as fertilizer is usually mixed with organic fertilizer and diluted 10-15 times. It can also dissolve ferrous sulfate to 0.2% - 0.5% aqueous solution to irrigate the soil of plant roots. It should be noted that when preparing ferrous sulfate solution, it should be kept away from light and ventilation to avoid ferrous sulfate oxidation failure.