EM 8707 Soils having very low or low sensitivity tend to be slowly permeable and high in organic matter. In these soils, leaching is limited and there is maximum retention of chemicals by sorption into organic matter. Soils having high or very high sensitivity tend to be rapidly permeable and low in organic matter. They transport chemicals very readily and have very little capability to retain them. Top Pesticide movement ratings Pesticide movement ratings measure the tendency for pesticides to be carried through the soil below the root zone.
Persistence is a measure of the length of time the chemical remains active in the soil.
Mobility is a measure of a chemical's tendency either to move through soil with leaching water or to be retained in the soil by sorption on particles of clay and organic matter. A high Koc value means a chemical has a strong tendency to bond to soil organic matter. Chemical half life and Koc are combined into a single index number, the groundwater ubiquity score, or GUS for short. The range of GUS values is divided into six classes of pesticide movement ratings, ranging from extremely low to very high. Chemicals at the low end of the scale tend to have very high Koc values and relatively short half lives.