Does an Increase in Levels of Acid Affect Bean Seed Germination Results?

Bean Soil pH

• Beans grow best in moderately acidic to neutral soils, with a pH range of 6.0 to 6.8. A soil that is below 5.5 will need to be amended with lime to increase the pH to tolerable levels. The proper acidity range is important to bean and other plant growth. The ideal pH will allow the plant to take up and utilize nutrients, while an incorrect pH can minimize the effectiveness of this process. If soil pH falls below 4 or above 9, a plant will die because it cannot access the nutrients it needs.

Acid Water

• Acid rain is a very real element and has the potential to adversely affect plant growth globally. The reason for this is it raises the pH levels of soils; in a large quantity it could raise them to unhealthy levels. The more acidic the water or solution used to water bean plants, the less they thrive. This is again due to the inability of the plant to access soluble nutrients.

High pH

• High-pH soils are actually alkaline. In some cases, a high soil pH can result in iron chlorosis, a condition that occurs when the plant cannot access iron, an important macronutrient, because the iron is chemically fixed in the soil in a form that plants can't utilize. In the 1970s and 1980s, and again in 2009, soybeans were widely planted in Alabama in soil with a pH of 7.5 and above. These plants suffered from iron chlorosis, produced poorly and were weak and spindly. Even topical applications of foliar fertilizers high in iron failed to rally the plants. At such pH levels the addition of sulfur may be attempted to make the soil more acidic and reduce the pH.

Low pH Equals Happy Plants

• Sulfur can be added to soils to decrease the pH and make them more acidic. Low pH levels on bean farms can reduce the incidence of root rot and increase the yield of the plants overall. In Minnesota, kidney beans were grown in soil with a pH of 5.1, which is generally considered too low, but they thrived even when the soil wasn't amended with lime to sweeten it to the recommended pH levels. Beans have the ability to tolerate very acidic soils, and crop production is only diminished when pH is below 4.6 and the plants' nutrient needs are not met.