Which soil type usually has the greatest nutrient retention?

• A. Clay soil
• B. Sandy soil
• C. Silt
• D. Loamy soil

Answer: (A)

Nutrient retention depends on how well the soil can hold positively charged nutrient ions, which is tied to cation exchange capacity (CEC). Clay minerals have a very large surface area with negative charges, and organic matter adds even more sites for holding nutrients. This combination gives high CEC, so clay soils attract and hold onto nutrient cations like calcium, magnesium, potassium, and ammonium, releasing them slowly as plants need them. That’s why clay soils typically retain the most nutrients.

Sandy soils, in contrast, have coarse particles and far less surface area, so they have low CEC and nutrients are more easily washed away by water. Silty soils are in between—more surface area than sand but less than clay—so their nutrient retention is moderate. Loamy soils mix textures and organic matter, providing good fertility, but their overall capacity to hold nutrients is usually not as high as pure clay.