Two-dimensional Analysis of Capillary Supply by Irrigation and Crop Water Uptake under Drip Irrigation

Abstract

A two-dimensional unsaturated soil water flow with root uptake under drip irrigation was modelled using numerical techniques. Capillary supply and percolation loss in the root zone, side zone and lower zone were estimated by the model under drip irrigation. The numerical solution used was the Finite Element Method. Soil water distribution was measured by the gamma ray attenuation method. The following results were obtained:
1) Soil water content estimated using the model simulation was compared with measured values and found to be within an average relative error of 39%.
2) Total amount of capillary supply estimated using the model simulation was compared with measured values and found to be within an average relative error of 15%.
3) It was observed that water losses due to percolation later became available to the plant through capillary supply.
4) The study also showed that capillary supply increased with increased remaining soil water.
5) From the model results, using existing sugarcane root distribution field data, it was suggested that the model could be used in irrigation scheduling.