Acid Rain & Bean Plants

Acid Rain Basics

• Acid rain is precipitation characterized by unusually high concentrations of hydrogen ions. This makes the rain much more acidic and corrosive than regular rain that approaches a neutral (7.0) pH. It comes from the emission of various pollutants like carbon dioxide, sulfur dioxide and nitrogen oxides. These pollutants interact with any moisture in the atmosphere and create acids, which then rain down during storms or showers.

Changing the Soil

• Acid rain storms may change the pH of the bean plant's soil, particularly if you have your beans planted outside. The ideal pH range for growing most types of beans is between 6.0 and 7.0, but prolonged exposure to acidic precipitation will inevitably lower the soil's alkalinity.

Potential Problems

• Soils below a 5.0 pH may cause a host of problems in bean plants. These include aluminum toxicity and magnesium and calcium deficiency. The plant will be unable to fix nitrogen levels, stunting its growth and turning it yellow. Aluminum and manganese become much more soluble in acidic environments, so the plants are more likely to absorb higher quantities of them. This will lead to complications like dead spots or wilting.

Raising the pH

• You may need to raise the pH of your bean's soil after an acid rain storm to bring it back up to normal levels. You can raise pH by applying hydrated lime into the soil or wood ash. However, raising the pH is a slow and delicate process, so always test the pH of the soil first using a testing kit and realize that it may be several days before the soil is brought up to normal levels.