What is liming, why is it used in rangeland soils, and how is lime requirement determined?

• A. Liming raises soil pH and adds base cations; used to reduce acidity and improve nutrient availability; lime requirement is determined by soil tests and target pH.
• B. Liming lowers soil pH and increases acidity.
• C. Liming adds nitrogen.
• D. Lime requirement is determined by planting density alone.

Answer: (A)

Liming is the practice of applying lime to soil to neutralize acidity, raise soil pH, and supply base cations such as calcium (and magnesium when using dolomitic lime). In rangeland soils, acidity often limits nutrient availability, microbial activity, and root growth, so liming helps create a more favorable environment for forage by reducing aluminum toxicity and increasing the availability of nutrients like phosphorus.

The lime requirement is determined from soil tests that measure current pH and the soil’s buffering capacity, then specify the amount of lime needed to reach a target pH appropriate for the desired vegetation. The recommended rate depends on the lime’s neutralizing value and the soil’s properties (texture, organic matter, existing exchangeable acidity). Choosing the right lime type (calcium- vs. magnesium-containing) also influences how much lime is needed. In practice, you take a representative soil sample, get it analyzed, and follow the lab’s guidance on the amount of lime to apply to reach the target pH.