What is it?
The acidity and alkalinity of soil is tested by a simple technique called the soil pH test. It can be further divided into different types based on the procedures. The measurement of hydrogen ions in the soil sample is common.
A reading of 7 on the soil pH scale indicates neutral soil, lower than 7 is acid soil, and 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 it?
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, and sodium. Generally, areas that receive low amounts of rainfall every year tend to have alkaline soil.
This is because the mineral salts that contribute to the alkalinity tend to retain in the soil in the absence of water. Mostly caused due to natural processes, increased pH levels could be brought about by long-term cultivation. For example, using hard water for watering plants may lead to increased alkalinity.
Just like water, sunlight and nutrients affect the overall growth of plants. Soil acidity or alkalinity plays an important role in a plant's life. A major gardening issue faced is reduced availability of some essential plant nutrients such as copper, iron, and magnesium to the plants growing in the area.
In addition, the microorganisms in the soil responsible for breaking down the nutrients remain in a dormant state at higher pH levels, thus reducing soil fertility.
Neutral pH soil which is moist and well-drained is preferred for growing healthy plants. If your garden soil pH reading is high or alkaline, you have two main approaches for treating it: one is lowering the soil pH, which is not very easy, and the other option is growing plants that can survive in alkaline soil.
Methods for correcting the soil involve supplementing it with chemicals like 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 a large variety.
It is important to understand soil science and choose plants after checking their required growth conditions. A simpler option is to ask your local horticulturist about the list of plants that adapt in this soil. Some alkaline soil plants are: