What Makes Soil Alkaline – Plants And Tips For Fixing Alkaline Soil

analog tool to measure ph of Alkaline Soil
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By Susan Patterson, Master Gardener

Just like the human body can be alkaline or acidic, so can soil. The pH of soil is a measurement of its alkalinity or acidity and ranges from 0 to 14 with 7 being neutral. Before you begin growing anything, it is good to know where your soil stands on the scale. Most people are familiar with acidic soil, but exactly what is alkaline soil? Keep reading for information on what makes soil alkaline.

What is Alkaline Soil?

Alkaline soil is referred to by some gardeners as “sweet soil.” The pH level of alkaline soil is above 7, and it usually contains a great deal of sodium, calcium and magnesium. Because alkaline soil is less soluble than acidic or neutral soil, availability of nutrients is often limited. Because of this, stunted growth and nutrient deficiency are common.

What Makes Soil Alkaline?

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In arid or desert areas where rainfall is slim and places where there are dense forests, soil tends to be more alkaline. Soil can also become more alkaline if it is watered with hard water that contains lime.

Fixing Alkaline Soil

One of the best ways to increase acidity in soil is to add sulfur. Adding 1 to 3 ounces of ground rock sulfur per 1 square yard of soil will lower pH levels. If the soil is sandy or has a lot of clay, less should be used, and it needs to be mixed in very well before using.

You can also add organic matter such as peat moss, composted wood chips and sawdust to bring down the pH. Allow the material to settle for a couple of weeks before retesting.

Some people prefer to use raised beds where they can control the soil pH easily. When you use raised beds, it is still a good idea to get a home soil test kit so that you know where you stand as far as pH and other nutrients are concerned.

Plants for Sweet Soil

If fixing alkaline soil isn’t an option, then adding suitable plants for sweet soil may be the answer. There are actually a number of alkaline plants, some of which may signal the presence of sweet soil. For example, many weeds are commonly found in alkaline soils. These include:

Once you know your soil is sweet in a given area, you still have the option of growing some of your favorite plants. Vegetables and herbs for sweet soil include:

Some flowers also tolerate soil that is slightly alkaline. Try the following:

Shrubs that don’t mind alkalinity include:

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