What factor contributes to the transformation of bound nutrients to soluble forms?

• A. Water movement downstream facilitates the transformation of nutrients.
• B. Increased soil adsorption of nutrients.
• C. Sedimentation of nutrients to the bottom.
• D. Atmospheric deposition of nutrients.

Answer: (A)

Bound nutrients become soluble mainly when they are released from soil particles by water moving through the system. As water flows, ions are displaced from attachment sites on clay and organic matter in a process called desorption, and minerals can dissolve a bit more in the presence of water. This movement and dissolution push nutrients into the soil solution, making them available for uptake or transport downstream. The other ideas don’t promote this release: more adsorption keeps nutrients bound and less soluble; sedimentation removes dissolved nutrients from the solution rather than transforming bound forms; atmospheric deposition adds nutrients but doesn’t release the ones already bound to soil.