How to Lower Soil pH: A Comprehensive Guide
Understanding Soil pH
The pH of soil measures its acidity or alkalinity on a scale of 1 to 14. A pH below 7 indicates acidic soil, while a pH above 7 indicates alkaline soil. Most vegetables, fruits, and ornamentals grow well in neutral soils (pH 6.5 to 7.5). However, certain plants, such as blueberries, azaleas, and hydrangeas, require acidic soil to thrive.
Testing Soil pH
To determine your soil type, it’s essential to test its pH level. You can send a soil sample to a cooperative extension office for a basic analysis or purchase a test kit from a retail outlet or garden center. Alternatively, you can perform a simple test using ingredients from your kitchen cupboard.
Lowering Soil pH with Sulfur
Elemental sulfur is commonly used to lower soil pH. It reacts with soil bacteria to produce sulfuric acid, which reduces acidity. For effective results, soil temperatures must be above 55 degrees Fahrenheit.
Step-by-Step Guide to Lowering Soil pH with Sulfur
Materials:
- Sulfur
- Hand or wheeled spreader
- Rototiller, shovel, or hoe
- Hose
- Hard rake
Instructions:
- Apply Sulfur: Distribute sulfur over the planting area according to the results of your soil test.
- Work Sulfur Into the Soil: Use a shovel, hoe, or rototiller to incorporate the sulfur into the soil to a depth of 6 inches.
- Water the Treated Planting Bed: Water the soil, but avoid drenching it.
- Wait to Plant: Allow about a month for the sulfur to work before planting to prevent exposing plants to concentrated acidity.
Other Methods to Lower Soil pH
Natural Methods:
- Organic materials: Compost and manure can slowly reduce soil pH.
- Pine products: Pine mulches, barks, and needles lower pH but break down gradually.
Chemical Methods:
- Ammonium nitrate: This fertilizer lowers pH quickly but requires repeated applications.
Factors Affecting Soil pH
The natural pH of soil is influenced by its geological origin, climate, vegetation, and time. Certain fertilizers and amendments can also affect soil pH. For example, fertilizers containing ammonium sulfate and nitrogen can reduce pH over time, while minerals and salts in hard water can raise pH.
Maintaining Soil pH
Soil acidity is depleted over time, making it necessary to maintain a neutral pH for optimal plant growth. Adding well-composted organic material and mulches annually is an effective way to sustain a balanced pH level.
Cautions:
- Always wear gloves, safety glasses, and protective clothing when working with chemicals.
- Avoid using vinegar to lower soil pH, as it requires large amounts and is time-consuming to dilute.
- Excessive sulfur application can damage plant roots and nutrient uptake.
