How Do Acids & Bases Affect Green Plants?

The effects of acids and bases (akalines) on green plants vary. Depending on their concentrations, they can either damage or improve plant health. The effect of acid on plants become most evident in the 1980s as people saw the tops of trees being killed by acid rain. However, acids and bases have been used for centuries as part of the fertilizers used to give plants nutrients they need to thrive.

Acid rain is primarily the result of emissions sulfur dioxide (SO2) and nitrogen oxides (NOx) because of coal and gas combustion. In the 1980s, prior to controls implemented by the EPA, leaves of higher elevation trees in the US and elsewhere were being eaten, weakening the tree from the top down.

A proper pH level (a measure of the alkalinity or acidity of a solution), ensures plant health. With imbalanced pH levels, plants can wither, refuse to grow or become sick. In one test, plants in soil with lower pH levels (acidic) tended to result in burnt leaves and lacked sturdy stems. Plants in higher pH growth medium tended to have splotchy leaves, produced deformed fruit and died.

Depending on where you live, your soil already contains certain amounts of acids or bases. This can determine what types of plants grown in an area and what plants are suitable to be grown. Similarly, prepared growth mediums for plants can be designed for certain plants.

Fertilizers actually are rated by their acidity or basicity; the acid being used is nitric acid. According to University of Massachusetts Amherst, fertilizer rated 15-16-17 means 215 pounds of calcitic limestone is required to neutralize the acidic effect ton of 15-16-17 fertilizer. A fertilizer rated 15-0-15 would raise the pH of the soil or growth medium by 420 pounds.

Most plants live well with pH levels between 6.0 and 7.0. Many crops prefer soils that are slightly more base (higher pH), while evergreens, Azaleas, Blueberries and Rhododendrons thrive in soil that is more acidic.