Why are soil particles able to attract cations?

• A. Because cations are negatively charged.
• B. Because soil particles are negatively charged.
• C. Because soil particles are positively charged.
• D. Because water in soil creates attraction.

Answer: (B)

Soil particles attract cations because their surfaces carry negative charges. Clay minerals and organic matter have these permanent negative charges, created by their mineral structure and functional groups. Those negative sites draw positively charged ions from the soil solution, a process known as cation exchange. Water around ions helps them move and surround the ions, but the attraction itself is due to the negative charge of the soil particles. This is why soils have a cation exchange capacity, enabling nutrients like calcium, magnesium, potassium, and others to be held and exchanged on the soil surface.