The ideal soil type for SDI systems is well-draining, with a moderate to high water-holding capacity. Soils with high sand or silt content are suitable, as they allow for easy water infiltration and minimal runoff. Clay soils can also be used, but may require additional design considerations, such as increased emitter spacing and flow rates, to prevent waterlogging. Avoid using SDI in soils with high water tables or poor drainage, as this can lead to waterlogging and reduced system efficiency.