Which measurement is used to determine lime requirement in soils?

• A. Buffer pH
• B. Soil texture
• C. Electrical conductivity
• D. Organic matter

Answer: (A)

Lime requirement is about how much lime is needed to neutralize soil acidity and raise the pH to a target level. The best way to gauge that is a buffer pH test because it directly probes the soil’s reaction to a standardized lime-like neutralization. By mixing soil with a buffered solution and measuring the resulting pH, you get an index that reflects both the current acidity and how strongly the soil resists pH change (its buffering capacity). That’s what tells you how much lime must be added to reach the desired pH.

Other measurements don’t give this direct estimate. Soil texture tells you the proportions of sand, silt, and clay, which affects how quickly lime works but not the exact amount needed. Electrical conductivity measures salinity, not lime requirement. Organic matter influences buffering and nutrient availability, but it doesn’t specify how much lime to apply.