Once the rice ferrous sulfate deficiency, the whole leaves of rice will turn yellowish-while except the costa and lateral veins staying a bit green .What kind of situation would cause rice ferrous deficiency? As this symptoms appears, how to control?
1. The soil conditions: Usually, rice seldom appears ferrous sulfate deficiency, however, it will often irrigated by factory waste-water with sodium or calcium that could make soil alkaline. Therefore, such occasion affect the absorption of ferrous and appear ferrous deficiency disease.
2. Improper fertilization: excess phosphate fertilizer can cause lack of ferrous , the main reasons are: (1) Excess hard dissolved phosphate radical reduce the effective ferrous in soil .; (2) Phosphate radical absorbed in by rice can also combines ferrous into hard dissolved compounds that influent ferrous mobility in the body .Ferrous cannot participate in the normal metabolization then loses its physiological activity; (3) The rise of phosphate concentration in rice makes pH go up that influent ferrous reduction and solubility. The ferrous utilization discounted. In addition, potassium nutritional deficiencies also can affect the utilization of ferrous. When such ferrous deficiency occurs, sometimes rice even appear potassium deficiency and ferrous deficiency symptoms at the same time.
3. Climate conditions: over rainfall is the main climate factor that affects the rice ferrous deficiency. After moistured by more rain, the free calcium carbonate in ash soil dissolve and produce the massive HCO3-. For the poor ventilation, CO2 produced by the root system and soil microbial respiration cannot promptly to escape to the atmosphere. It also help to accumulated HCO3-. The increase of the concentration of HCO3- bring ferrous’s effectiveness down. That cause ferrous deficiency.
The prevent solution.
1. The application of ferrous fertilizer: Ferrous chelate compound even in a neutral or alkaline soil condition are rarely insoluble. Fertilizing 2 ~ 3 kg ferrous sulfate heptahydrate every 667 m2 is better.
2. Application of acidic fertilizer: Application of ammonium sulfate, ammonium chloride and potassium that adjust soil to be acidic.
3. Foliar spraying: foliar spraying ferrous sulfate or ferric chloride solution. For the ferrous within the body is not easy to move, only the part that ferrous solution attached can recovery green, the rest are still appear deficiencies. The best way is to spray rounded with more diluted solution and repeated many times. Concentration of ferrous sulfate solution is 0.1 ~ 0.2%.