Soil pH—A Crucial Factor Determining What
You Can Grow in Your Garden
Soil pH is a measure of how acid or base your soil is. pH is measured using a pH scale between 0 to 14, with acids having a pH from 0 to 6.9 and bases having a pH from 7.1 to 14. A pH of 7 is neutral, neither acidic or basic. For instance, lemon juice and battery acid are acidic and fall in the 0-7 range, whereas seawater and bleach are basic (also called "alkaline") and fall in the 7-14 pH range. Pure water is neutral, or 7 on the pH scale. The Importance of Soil pHThe pH of soils is very important because they carry nutrients such as Nitrogen (N), Potassium (K), and Phosphorus (P) that plants need to grow, thrive, and fight off diseases. When the pH of the soil solution reaches above 5.5, nitrogen becomes available to plants. Phosphorus becomes available to plants when soil pH is between 6.0 and 7.0. Certain bacteria help plants obtain nitrogen by converting atmospheric N2 into a form that plants can use. These bacteria live in root nodules of legumes (like alfalfa and soybeans) and function best when the pH of the soil the plant they live in is within an acceptable pH range. If the soil is too acidic, plants cannot utilize N, P, K and other nutrients they need. In acidic soils, plants are more likely to take up toxic metals. Some plants eventually die of toxicity (poisoning). For instance, alfalfa grows best in soils having a pH of 6.2 - 7.8, while soybean grows best in soils with a pH between 6.0 and 7.0. Peanuts grow best in soils that have a pH of 5.6 to 6.6. Many other crops, vegetables, flowers and shrubs, trees, weeds and fruit are pH-dependent. The following chart is an example of pH ranges for the world, a rough color chart for soil pH. This chart is from Wikipedia.
Global variations in soil pH.Red = acidic soil.
Yellow = neutral soil.
Blue = alkaline soil.
Black = no data From Soil pH to Soil
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