What process moves nutrients downward with water?

• A. Leaching
• B. Nitrogen fixation
• C. Transpiration
• D. Evaporation

Answer: (A)

Nutrients dissolved in water moving downward through the soil happens when water infiltrates and percolates, carrying dissolved minerals with it. This downward transport is leaching, which can remove soluble nutrients like nitrate, potassium, and sulfate from the surface root zone and deliver them to deeper layers or groundwater, especially after heavy rainfall or irrigation. Transpiration moves water upward from roots to the atmosphere via the plant, not downward through the soil, so it doesn’t move nutrients downward. Evaporation is the surface loss of water to vapor and also doesn’t transport nutrients through the soil. Nitrogen fixation is a biological process that adds usable nitrogen to the soil rather than moving existing nutrients downward with water.