MDARD Michigan Core Pesticide Applicator Practice Exam

Which type of soils is more adsorptive than sandy soils?

1. Sandy soils

2. Clay soils

3. Soils high in organic matter

4. Soils with low organic content

The correct answer is: Soils high in organic matter

Clay soils are more adsorptive than sandy soils primarily due to their finer texture and higher surface area. The small particle size of clay allows for more surface interaction, which leads to a greater capacity for holding and binding various substances, including nutrients and pesticides. These interactions are influenced by both the physical and chemical properties of the clay particles, which are able to retain water and nutrients more effectively than the larger, coarser particles found in sandy soils. Moreover, soils high in organic matter also enhance adsorptive capacity. Organic matter contributes additional sites for adsorption and can improve soil structure, moisture retention, and nutrient availability. This is in contrast to sandy soils, which have larger particles and larger pore spaces, resulting in lower adsorptive ability. Thus, in comparison to sandy soils, both clay soils and soils high in organic matter are capable of holding onto materials like water and pesticides more effectively, making them more adsorptive overall.