Alkaline Soil—Tough Growing Conditions
That Can Be Improved
Alkaline soil is soil with a pH higher than 7.0. It's also called sweet or basic soil (compared to acidic soil, which is called sour soil).
Alkali soil has high levels of sodium, and is quite different from alkaline soil.
Alkaline soil have the minerals sodium, magnesium and calcium present in the soil.
Areas that receive less than 20 inches of rain per year most usually are alkaline.
Hard water with a high lime content will increase the alkalinity of the soil.
If your soil has a lot of free limestone (calcium carbonate) with a pH of 8.2, you'll have a hard time keeping the pH low for any length of time.
You'll need a lot of acidic organic fertilizers or acidic mulches, such as pine needles.
Many plants will grow well in alkaline soil from pH 7.1 to 7.4. A pH of 7.5 or higher will decrease the chances of good plant growth.
Soil with high alkalinity will hinder plant growth. Alkalinity problems will emerge, such as plants becoming chlorotic (there's a lack of available iron in the soil for plants).
In this case, there's probably iron present in the soil, but it's not in an available form. By lowering the soil's pH, the iron will become (more) available.
A List of Acidic Soil pH Levels
- 7.0 is neutral
- 7.1 to 7.5 is very slight alkaline
- 7.5 to 8.0 is slightly alkaline
- 8.0 to 8.5 is medium alkaline
- 8.5 to 10.0 is strongly alkaline
Examples of Acidity and Alkalinity
- Water that's purified is neutral (pH 7.0).
- Baking soda is a mild base (alkaline).
- Drano is strongly alkaline.
Have a soil test that checks the pH done every couple of years to ensure the best growing conditions for your area (whether acidic or alkaline).
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