Soils with higher organic matter content hold more water and adsorb more pesticides, reducing leaching.

• A. False
• B. Depends on rainfall
• C. Not always true
• D. True

Answer: (D)

Higher organic matter in soil increases both its ability to hold water and its capacity to sorb pesticides. The porous, complex structure of organic matter creates more micro- and macro-pores that trap and retain water in the root zone, so the soil stores moisture rather than letting it drain away quickly. It also provides numerous binding sites through functional groups that interact with many pesticides, especially those that are hydrophobic, causing those chemicals to bind to the soil rather than move with infiltrating water. When pesticides are sorbed, they are less available for movement with percolating water, which slows or reduces leaching to deeper layers or groundwater. Rainfall can influence the extent of leaching, but the basic tendency is that more organic matter leads to more water retention and more pesticide sorption, thereby reducing leaching overall.