Which type of herbicide is typically more mobile in the soil?

Long-term residual herbicides are designed to remain active in the soil for an extended period of time. Their formulation often allows them to be more mobile in the soil, which means they can travel with water movement through the soil profile. This mobility can help in controlling a broader range of weeds over a longer duration, as they inhibit weed growth even after application.

Non-residual herbicides do not persist in the soil and quickly break down, leading to less concern about mobility since they are intended for immediate action rather than long-term control. Volatile herbicides, while they can evaporate quickly, are typically not assessed for mobility in soil as their active components may not rely solely on soil interactions. Pre-emergent herbicides are designed to prevent weed seeds from germinating and usually work best when placed in the top layer of soil, thus their mobility may be limited in comparison to long-term residual herbicides that are formulated specifically for prolonged action and movement within the soil matrix.