Predicting the field characteristics of drip irrigation

The measurements of sorptivity and conductivity for the surface and subsurface Lavalette soil, as presented in the previous paper, are used here to infer the salient features of drip irrigation experiments. Good prediction of the size of the free-water pond was obtained via Wooding's equation. Reasonable success was achieved with application of Raats' solution for the steady radial and vertical profiles of water content. However the soil's drop-off in conductivity with depth probably contributed to the observation of a greater lateral spread of water than the capillarity of the surface soil could alone sustain. Nevertheless Raats' solution is shown to be easy to parameterise. It is potentially useful for predicting solute travel times away from drippers, at least in unstratified soils.