Alkaline Soil – Definition & Detailed Explanation – Horticultural Terms Glossary

I. What is Alkaline Soil?

Alkaline soil, also known as sweet soil, is soil that has a pH level above 7.0. This means that the soil is more basic than acidic. Alkaline soil is characterized by its white or gray color and can often be found in areas with limestone or chalk bedrock. This type of soil is less common than acidic soil, but it can present challenges for gardeners and farmers looking to grow certain types of plants.

II. What Causes Alkaline Soil?

There are several factors that can contribute to the development of alkaline soil. One of the main causes is the presence of limestone or chalk bedrock in the area. When these rocks break down over time, they release calcium carbonate into the soil, which raises the pH level. Additionally, overuse of lime-based fertilizers can also lead to alkaline soil. Other factors that can contribute to alkaline soil include irrigation with water that has a high pH, poor drainage, and a lack of organic matter in the soil.

III. How to Test for Alkaline Soil

Testing the pH level of your soil is essential to determine whether it is alkaline or acidic. You can purchase a soil testing kit from a garden center or send a sample of your soil to a lab for analysis. To test for alkaline soil, simply follow the instructions provided with the testing kit or lab submission form. The results will indicate whether your soil is alkaline, acidic, or neutral.

IV. How to Amend Alkaline Soil

If your soil test reveals that you have alkaline soil, there are several ways to amend it to make it more suitable for growing a wider variety of plants. One common method is to add sulfur to the soil. Sulfur helps to lower the pH level of the soil, making it more acidic. You can also add organic matter, such as compost or manure, to improve the soil structure and nutrient content. Another option is to use acidifying fertilizers that contain ammonium sulfate or ammonium nitrate.

V. Plants that Thrive in Alkaline Soil

While alkaline soil can present challenges for some plants, there are many varieties that actually thrive in this type of soil. Some examples of plants that do well in alkaline soil include lavender, yarrow, Russian sage, and butterfly weed. These plants have adapted to the high pH levels and can tolerate the conditions found in alkaline soil. It’s important to choose plants that are well-suited to your soil type to ensure they thrive in your garden or landscape.

VI. Common Mistakes to Avoid when Dealing with Alkaline Soil

When dealing with alkaline soil, there are several common mistakes that gardeners and farmers should avoid. One mistake is over-fertilizing with lime-based products, as this can further raise the pH level of the soil. It’s also important to avoid using alkaline water for irrigation, as this can contribute to the alkalinity of the soil. Additionally, planting acid-loving plants in alkaline soil without amending it first can lead to poor growth and nutrient deficiencies. By being aware of these common mistakes and taking steps to amend alkaline soil, you can create a healthy and productive growing environment for your plants.