What is Alkaline Soil?

Alkaline soil, also known as basic soil, is a type of soil that has a high pH level. The pH level of soil is a measure of its acidity or alkalinity, with a pH of 7 being considered neutral. Alkaline soil has a pH level above 7, typically ranging from 7.5 to 8.5. This means that alkaline soil is more basic than neutral or acidic soil.

Causes of Alkaline Soil

There are several factors that can contribute to the development of alkaline soil. One of the main causes is the presence of high levels of calcium carbonate, also known as lime, in the soil. This can occur naturally in areas with limestone bedrock or as a result of human activities such as the application of lime to agricultural fields. Other factors that can contribute to alkaline soil include high levels of sodium, magnesium, or potassium, as well as poor drainage and excessive irrigation.

Effects of Alkaline Soil on Plants

The high pH level of alkaline soil can have a significant impact on plant growth and health. Many plants have specific pH requirements for optimal growth, and alkaline soil can make it difficult for them to absorb essential nutrients from the soil. This can lead to nutrient deficiencies and stunted growth. Additionally, alkaline soil can also affect the availability of certain minerals, such as iron and manganese, which are essential for plant development. As a result, plants grown in alkaline soil may exhibit symptoms of nutrient deficiencies, such as yellowing leaves or poor fruit production.

Amending Alkaline Soil

If you have alkaline soil in your garden or agricultural field, there are several steps you can take to amend it and create a more favorable environment for plant growth. One common method is to add organic matter, such as compost or well-rotted manure, to the soil. Organic matter can help to improve soil structure and increase its ability to retain moisture, as well as lower the pH level of alkaline soil. Another option is to use soil amendments, such as sulfur or aluminum sulfate, which can help to acidify the soil and reduce its alkalinity. It’s important to note that amending alkaline soil is an ongoing process, as the effects of these amendments may not be permanent and may need to be repeated periodically.

Plants that Thrive in Alkaline Soil

While alkaline soil can pose challenges for many plants, there are some species that are well-adapted to these conditions and can thrive in alkaline soil. Some examples of plants that are known to tolerate or even prefer alkaline soil include lavender, yarrow, Russian sage, and butterfly weed. These plants have evolved to be able to extract nutrients from alkaline soil and have adapted their root systems to cope with the high pH levels. If you have alkaline soil in your garden, consider incorporating these plants into your landscape to ensure successful growth.

Preventing Alkaline Soil

Preventing the development of alkaline soil can be challenging, especially in areas with naturally high levels of calcium carbonate. However, there are some steps you can take to minimize the risk of alkaline soil formation. One approach is to regularly test the pH level of your soil and monitor any changes over time. This can help you identify potential issues early on and take corrective action if necessary. Additionally, practicing proper soil management techniques, such as avoiding over-irrigation and ensuring good drainage, can help to prevent the accumulation of salts and other alkaline substances in the soil.


In conclusion, alkaline soil is a type of soil that has a high pH level above 7. It can be caused by factors such as high levels of calcium carbonate or other alkaline substances in the soil. Alkaline soil can have negative effects on plant growth and health, but it can be amended through the addition of organic matter or soil amendments. Some plants are well-adapted to alkaline soil and can thrive in these conditions. Preventing the development of alkaline soil requires regular soil testing and proper soil management techniques. By understanding alkaline soil and taking appropriate measures, gardeners and farmers can create a more favorable environment for plant growth and ensure successful cultivation.