Nitrate is leached from soil more readily than ammonium because nitrate:

1. Soil colloids, the clay and humus particles, carry a net negative charge. 2. Ammonium, $NH_4^+$, is a cation, so those negative sites attract and hold it by cation exchange. 3. Nitrate, $NO_3^-$, is an anion, so the same negative sites repel it. 4. Having nothing to hold it, nitrate stays free in the soil water. 5. Draining water therefore washes nitrate down through the profile, which is leaching. _Source: NECTA ACSEE 2024 Chemistry 132/1, Question 8: Soil Chemistry and Environmental Chemistry_