Question: In the soil, ammonium has a much longer residence time than nitrates do. Why do these two molecules behave so differently? Responses Nitrates are only produced when there is a high rate of water flowing through the soil. Nitrates are only produced when there is a high rate of water flowing through the soil. The positive charge of the ammonium molecules allows them to stick to soil particles better. The positive charge of the ammonium molecules allows them to stick to soil particles better. Ammonium is unavailable for use by organisms in the soil, so it remains in its original form. Ammonium is unavailable for use by organisms in the soil, so it remains in its original form. Nitrates are easily broken down by soil bacteria, so they get carried away more frequently. Need Assignment Help?