What Is the Meaning of Alkaline?
Alkaline or alkalinity is a term that describes the pH balance of a substance. Alkaline substances--be they liquid or solid--have above-average pH levels, which makes them the opposite of acids. In your garden, some plants like their soil slightly alkaline. Most, however, can be hurt by too much alkalinity. To grow a successful, bountiful garden, it helps to understand alkalinity, pH and soil balance. Does this Spark an idea?
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The pH Scale
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All substances can be measured by their pH, which stands for "power of Hydrogen." PH is measured on a scale of 0 to 14: The numbers indicate the amount of free hydrogen ions that are present in the substance. The very strongest acids are pH 0; strongest bases are pH 14. Distilled water is the only common substance that has a neutral pH: in pure water, all hydrogen ions are attached to water molecules. Distilled water has a pH of 7, which is neutral.
The pH scale is logarithmic, meaning that a pH of 4 is 10 times stronger than a pH of 3.
Alkalinity vs. Acidity
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"Alkaline" is another word for "basic." Bases, or alkaline substances, are the opposite of acids. Whereas acids have an excess of hydrogen ions, bases have very few. The strongest common acid is battery acid, and the strongest common base is drain cleaner. Both of these chemicals are highly corrosive. Most acids and bases, however, are much weaker. Black coffee, for example, has a pH of 5. Baking soda's pH is 9. Acids tend to taste sharp or sour, and bases usually taste bitter.
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pH in Soil
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It's common for soil to become acidic in areas with high rainfall. These areas tend to have high levels of decaying organic matter, which turns acidic as it degrades. Areas with low rainfall, on the other hand, tend to turn alkaline. This can be due to mineral deposits, chemicals and salts in the soil that are not washed away with rain.
Effects of Alkalinity on Plants
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Most plants grow best in a soil with a pH range from 6 to 7.5. At this range, most nutrients are readily available and easy for plants to absorb through their roots. In alkaline soils, the nutrients are often less available, causing plants to "starve." There are plants, for example, olives, that are adapted to alkali; however, even they will fail if the pH is too high.
Amending Alkaline Soil
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To control your soil's pH, have it tested. Take a soil sample to your local garden center to find out what the pH level is, and what, if any, nutrients are missing. Then till in a soil amendment. There are several chemicals that will lower your pH. Sulfur is the cheapest, but sphagnum peat and ferrous sulfate add helpful nutrients. You can also continually add organic material and compost to your soil, which will steadily lower the pH over time and provide more nutrition for your plants.
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- Photo Credit desert land image by Danil Vachegin from Fotolia.com
