Can Worm Castings Correct pH in Soil?

Worm Castings

• Since the pH of worm castings is higher than the ideal zone for most plants, they could be used to neutralize acidic soil, though large amounts would be required to create a significant change. Castings erode in the soil after two months and would need to be replaced to have a continued effect on pH. To maintain a more neutral soil in climates with consistently acidic soil, worm castings may help if used regularly.

Benefits of Worm Castings

• Aside from mild effects on pH levels, worm castings provide the soil with many healthy components. Worm castings are full of essential nutrients left over from worms digesting plant matter. The castings also help build healthy soil structure with greatly improved drainage capacity. Castings support the microorganisms in the soil by depositing live beneficial bacteria. These bacteria continue to break down organic matter in the soil, leaving behind rich humus.

Options for Correcting pH

• Most plants need soil with a pH of about 6.5, however a few plants, such as blueberries, azaleas and tomatoes, thrive in slightly more acidic soil. It is important to know the specific pH requirements of individual plants and to plant those with similar requirements near each other. To neutralize acidic soil, lime is the most effective soil amendment. For neutralizing alkaline soil, spaghnum peat, elemental sulfur, aluminum sulfate or iron sulfate work well.

Importance of pH Levels

• Correct soil pH is essential to plant health. If the pH strays too far from the ideal range, nutrients become unavailable for plant uptake. Most essential nutrients are only available to plants in soil pH ranging from 6.0 to 7.5. Incorrect soil pH will cause plants to display symptoms of nutrient deficiency and can cause plant death if not corrected. Using soil tests to determine amendment usage is the best way to maintain correct soil pH.