How Does Soil Affect the pH of Water?

Overview

The acidity or alkalinity within the soil is a powerful influence over plant growth throughout nature. The absorption of nutrients necessary for the proper development of plant life depends on the right balance of pH levels in the environment. These pH levels can be altered by the introduction of acidic water as it meets naturally alkalic soil.

Soil and Water

At the point where soil and water meet, their acidity levels are immediately combined and influence each. As the water drains away, it retains a slightly different acidic content then it had before. This acidity will govern which plants will properly grow and how easily their roots will be able to absorb the necessary nutrients they need to survive.

pH Levels

Both soil and water are measured with a pH scale. The middle of the scale, where the pH level is neutral, as in salt or pure water, is 7. The lower the pH level, the more acidic the solution. The higher the pH levels, the more alkalinity present. The pH level of materials naturally changes by the introduction of other materials.

Soil Interaction

As rainfall reaches the surface of the earth, vapors may come in contact with various particles that can slightly lower the overall pH level. Soil, on the other hand, often has traces of alkaline materials, like limestone. As the acidic particles of the rain meet the alkaline nature of the soil, a chemical reaction takes place. The acidity within the rain and the alkalinity within the soil become mutually neutralized.

Water

Water is better able at retaining its pH level than soil is. It often takes larger amounts of pH materials to alter water structures. Some large materials, like bedrock, gold or limestone, present in soil can quickly raise the level of pH of rainfall and irrigation as it passes through.

Heavy Rains

In areas that experience heavy rainfall, acidic water will wash away the alkaline elements within the soil or neutralize them. The water will retain the majority of its acidic qualities and contribute to overall lower pH levels in the environment.