What Happens to Grass Exposed to Weak Acid Rain?

Weak Acid Rain

• Normal rainwater has a pH, or salt-acid level of 5.5 to 5.6. Weak acid rain refers to the level of dissolved acids in the rain created by carbon dioxide gases from the air resulting in increased acidity above the normal pH levels. On the pH scale, zero represents the highest acidity level and at the other end of the scale, 14 equates to the highest alkaline or salt level with 7.4 being the neutral point. Rainwater with a pH level of 4.0 to 4.6 falls within the weak acid rain category. Weak acid rain also goes by the name of acid precipitation, since carbon dioxide gases can intermix with dew, snow, frost and fog as well as with rain. As grass and soil can readily absorb oncoming rain, increased acidity levels may develop.

Grass Growth Needs

• Like most other plant forms, grasses rely on sunlight, water and carbon dioxide to manufacture food and provide fuel for growth. Through photosynthesis, grasses take in carbon dioxide and light from the environment and combine these materials with water from the soil to produce sugars. As weak acid rain carries carbon dioxide gases with it, grasses receive an added dose of carbon dioxide through the water contained in the soil. This increase in carbon dioxide increases acidity levels in the soil and in grasses.

Soil Environments

• Grass relies on soil environments to provide basic minerals and nutrients such as calcium, magnesium and iron. Grasses combine these materials with manufactured sugars to produce proteins, oils and fats. As soil environments absorb weak acid rain, soil pH balances change because of the additional acids contained in the rain. This increase in acidity affects the health of a soil’s microorganisms, which play a vital role in conditioning and sustaining soil ecosystems. Increased acid levels reduce the quality of nutrients available to soil microorganisms and grass plant roots.

Nutrient Availability

• As weak acid rains increase the acid content in soils, minerals dissolve away more rapidly than when normal rains occur, depleting soil environments of nutrients. Much like other plants, healthy grass and soil environments require certain pH levels depending on the type of soil and the nutrient needs within the ecosystem. Increased acid levels create chemical imbalances in the soil that offset nutrient availability for grasses and plants. Areas with high levels of acid rain weaken grass vegetation and over time, can kill off grass and plant life.