Which soil characteristic influences pesticide leaching?

• A. Soil color
• B. Soil texture and organic matter
• C. Soil depth
• D. Soil moisture

Answer: (B)

Downward movement of a pesticide through soil, or leaching, is governed most by how strongly the chemical is held by soil particles and how easily water and the chemical can move through the soil. Soil texture and organic matter content determine those holding and movement properties. In coarse-textured soils like sandy soils, there are large pores and less surface area to bind pesticides, so the chemical tends to travel with water and leach more quickly. In finer-textured soils with more clay and silt, there is more surface area and more sites to adsorb pesticides, which slows their downward movement and reduces leaching. Organic matter adds even more binding sites, further limiting leaching. So, texture and organic matter content are the main soil characteristics that influence how far a pesticide can leach. Soil color, depth, and moisture can influence leaching in specific situations, but they do not determine the pesticide’s tendency to move through the soil as strongly as texture and organic matter do.