SOIL-WATER DYNAMICS MODEL FOR TRICKLE IRRIGATED TOMATOES

A soil water dynamics model for establishing the wetting pattern of po int source trickle emitters under a tomato crop has been developed and verified. Infiltration from the point source trickle emitters in the presence of water extraction has been investigated by assuming a hemis pherical shape of the wetted soil volume and analytic expressions have been derived for determining the position of wetting front. Water ext raction by the plants has been estimated by using a macroscopic model of uptake utilizing root length. Daily values of water uptake have bee n used to update the volumetric moisture content in the root zone laye rs. The values of soil moisture content predicted by the model compare d well with the field-observed values. The predicted values were used to predict the radius of the hemispherical wetted soil volume which fo rms a basis for deciding emitter spacing for various crops and operati ng conditions. (C) 1998 Elsevier Science B.V. All rights reserved.