- Solute distribution around a trickle source for three-dimensional steady state flow is studied in terms of an approximate analytic model. Ion and water uptake by the root system are taken into account. Moisture flow and ion concentration profiles are assumed to have hemispherical symmetry. The distributions are nearly constant near the source, with a sudden increase or decrease closer to the wetting front, depending on the ion balance. A simple criterion for the highest allowed concentration is developed. The calculated profiles are compared with the results of field measurements on potassium and nitrate ions.