Alkaline soils occur in many parts of the country. High alkaline levels harm garden plants by interfering with their uptake of soil nutrients. Alkaline soils are common in areas with low rainfall or areas that have been heavily irrigated. Garden centers sell basic pH soil test kits that let you conduct your own testing and offer products for correcting pH imbalances.
Test your garden soil’s pH level with a home soil test kit. Record the reading. A pH reading of 7 is a neutral soil, not too acidic or alkaline. Most garden plants can handle an alkaline pH of 7.1 to 7.5. A pH level above 7.5 indicates an alkaline soil that may need correction.
Spread sphagnum peat moss over your garden plot in an even layer about 2 inches thick. Do this at the start of the growing season. Work it into the top 10 inches of soil with a garden fork or tiller/cultivator. Sphagnum peat moss is acidic, with a pH of around 4, which balances soil alkalinity. But it is expensive for large garden plots.
Apply granulated elemental sulfur instead of sphagnum peat moss on large garden plots. Apply evenly at the start of the growing season at a rate of 10 pounds per 1,000 square feet. Reduce the rate by 33 percent for sandy alkaline soils. Elemental sulfur combines with rainwater and soil moisture to create mild sulfuric acid that balances alkalinity. Retest the soil at the start of the next growing season, and treat again if needed.
Things You Will Need
- pH soil test kit
- Sphagnum peat moss (small plots)
- Granulated elemental sulfur (large plots)
- Garden fork or tiller/cultivator
- Don't use lime to treat alkaline soil. Lime is a popular soil amendment, but is only good on acidic soil. It will make alkaline soil worse.