Agronomy Degree Practice Exam

Which type of soil requires the least initial amount of agricultural lime to increase soil pH?

1. Loam

2. Clay loam

3. Silt loam

4. Loamy sand

The correct answer is: Loamy sand

Loamy sand requires the least initial amount of agricultural lime to increase soil pH due to its texture and composition. This type of soil has a higher sand content, which means it has larger particles and greater pore spaces compared to other soil types like clay loam or silt loam. Because of these characteristics, loamy sand tends to have lower cation exchange capacity and generally a higher level of permeability, allowing it to react more quickly to liming. When agricultural lime is applied to increase soil pH, the physical and chemical properties of the soil determine how much lime is needed. Soils with higher clay content, such as clay loam or silt loam, can hold more nutrients and are often more acidic, requiring more lime to achieve the desired pH level. Additionally, loamy sands can more efficiently absorb and integrate lime due to their structure, thus making the correction of soil acidity more effective with less lime than heavier, finer-textured soils.