The most common way to raise the pH in soil, making it less acidic, is to apply lime.
Understanding Soil pH and Why It Matters
Soil pH is a measure of the acidity or alkalinity of soil. A pH of 7.0 is neutral, below 7.0 is acidic, and above 7.0 is alkaline. Many plants thrive in a slightly acidic to neutral soil, but some prefer more alkaline conditions.
- Why is pH important? Soil pH affects nutrient availability. When the pH is too low (acidic), some nutrients become locked up and unavailable to plants, while others can become toxic.
Using Lime to Increase Soil pH
According to the reference, "to make soils less acidic, the common practice is to apply a material that contains some form of lime." Here's a breakdown:
- What is Lime? Lime is a general term for materials that contain calcium and magnesium carbonates, oxides, or hydroxides.
- Types of Lime:
- Ground Agricultural Limestone: This is the most frequently used type of lime.
- Dolomitic Lime: Contains magnesium as well as calcium, and is beneficial if your soil is deficient in magnesium.
- Hydrated Lime (Slaked Lime): Reacts quickly but is caustic and can burn plants if not used carefully. Not recommended for general use.
- Quick Lime (Burnt Lime): Highly caustic and reacts very quickly. Very dangerous and not recommended for general use.
How to Apply Lime
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Test Your Soil: Before applying any lime, it's essential to test your soil to determine its current pH and what type of lime is best for your specific needs. Your local agricultural extension office can provide information on soil testing.
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Choose the Right Lime: Select the appropriate type of lime based on your soil test results and plant needs. Ground agricultural limestone is generally a safe and effective choice.
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Particle Size Matters: The reference states, "The finer the limestone particles, the more rapidly it becomes effective." Finely ground lime will react with the soil more quickly than coarser lime.
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Application Rate: The amount of lime you need to apply will depend on your soil type, current pH, and target pH. Soil test results will provide specific recommendations.
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Application Method:
- Spread the lime evenly over the soil surface.
- Incorporate the lime into the top 6-8 inches of soil. Tilling or digging it in will help it react more quickly.
- Water the area after application.
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Timing: Fall is generally considered the best time to apply lime, giving it several months to react with the soil before planting in the spring.
Other Considerations
- Organic Matter: Adding organic matter, like compost, can also help buffer soil pH and improve nutrient availability.
- Slow and Steady: It's better to raise the pH gradually over time than to make drastic changes all at once.
- Retest Regularly: After applying lime, retest your soil every year or two to monitor the pH and make adjustments as needed.
