Which statement about the effect of lime on soil is true?

• A. It lowers pH and increases acidity
• B. It increases soil salinity
• C. It decreases organic matter
• D. It raises pH and lowers acidity

Answer: (D)

Lime works by neutralizing soil acidity. The carbonate in lime reacts with hydrogen ions and exchangeable aluminum in acidic soils, forming water and CO2 and reducing the amount of acidic ions held in the soil solution and on exchange sites. This causes the soil pH to rise and the overall acidity to decrease. In addition, lime supplies calcium (and sometimes magnesium), which helps improve soil structure and cation exchange capacity, supporting better nutrient availability in many acidic soils. It does not inherently raise soil salinity, nor does it decrease organic matter, so the true effect is raising pH and lowering acidity.