Alkaline Soil

In previous times, tasting garden soil was adopted by farmers to check the soil condition. With this simple trick, he could easily conclude whether it was suitable for growing crops or not. Even though soil tasting is not a precise or safe method, it helps in quick evaluation of the soil. A sweet taste signifies near neutral soil pH, while sour taste and bitter taste are indications for acidic soil and alkaline soil respectively. Here, we shall focus on the definition, causes, treatment and also plants that love to grow in this soil type.

What is Alkaline Soil?

The acidity and alkalinity of soil are tested by a simple technique, called soil pH test. It can be further divided into different types, based on the procedures. But, one thing is for common, i.e. measurement of hydrogen ions in the soil sample. In the soil pH scale, a reading of 7 indicates neutral soil, lower than 7 is acid soil, and lastly, pH reading higher than 7 is alkaline soil. As compared to other types of soil, a highly alkaline soil has less solubility and low infiltration capacity. Both these factors negatively affect the growth of plants.

What Causes Alkaline Soil?

The main cause for soil alkalinity is the presence of sodium carbonate in high percentage. Other minerals that may be detected in high amounts are calcium, magnesium, sodium, etc. Generally, areas that receive low amount of yearly rainfall tend to have alkaline soil. This is because the mineral salts that contribute to alkalinity tend to retain in the soil, in the absence of water. Mostly caused due to natural processes, increased soil pH levels could be brought about by long-term cultivation. For example, using hard water for watering plants may lead to increased alkalinity afterward.

Alkaline Soil Treatment

So, what is so special about soil pH or alkaline soil in growing plants? Just like water, sunlight and nutrients affect the overall growth of plants, there is a great role of soil acidity or alkalinity in a plant's life. A major gardening issue faced with this soil is reduced availability of some essential plant nutrients, such as copper, iron and magnesium to the plants growing in the area. In addition, the soil microorganisms responsible for breaking down of nutrients remain in the dormant state in higher pH levels, thus reducing soil fertility.

The preferred soil for growing healthy plants is the one having neutral pH with moist and well-drained conditions. If your garden soil pH reading is high or alkaline, you have at least two gardening approaches. One is lowering the soil pH, which is not very easy, and the other option is growing alkaline soil loving plants. Methods for correcting alkaline soil involve supplementing it with any of the chemicals, sulfur, aluminum sulfate, iron sulfate manganese or borax. However, this method requires close monitoring and soil pH tests at regular intervals, until you get a near stabilized pH range.

Alkaline Soil Plants

There are a certain group of plants that thrive well in higher soil pH levels, i.e., within the alkaline range. Whether you are planning to grow flowers, vegetables, vines, shrubs or trees, you will get your preferred varieties. The only thing is to understand soil science and choose plants after checking their required growth conditions. A simpler option is to take advice from a local horticulturist about the list of plants that adapt in alkaline soil. For your reference, some alkaline soil plants are mentioned below.

Small Plants (Herbs and Vegetables)

• Goldencup
• Kenilworth ivy
• Goosefoot
• Dandelions
• Baby's breath
• Japanese anemone
• Persian rockcress
• Sweet pea
• Common bean
• Chickweed
• Queen Anne's lace
• Hydrangeas
• Chicory
• Yams
• Asparagus
• Parsley
• Okra

Shrubs and Trees

• Japanese honeysuckle
• Chilean jasmine
• Daphniphyllum
• Feathery cassia
• Japanese quince
• Heather
• Littleleaf boxwood
• Silverthorn
• Cassina
• Lavender
• Holly oak
• Japanese plum
• Asian persimmon
• Olive tree
• Cedar elm

If you have time and patience, consider organic amendments to treat alkaline soil. Effective choices are peat moss, sphagnum moss and pine straw. These supplements will take a longer time for bringing down the garden soil pH to desirable levels, but they are better alternatives to using chemicals in garden soil.