Analysis of several discharge rate-spacing-duration combinations in drip irrigation system

In order to study the use of water irrigation in a rational way, several co mbinations of discharge rate, irrigation duration and inter-emitter distanc es were tested. For instance, three dripper spacings of 30, 50 and 70 cm. w hich delivered water volumes of 4, 8 and 16 1 per dripper, respectively, an d three discharge rates of 2, 4 and 8 1/h for each spacing, were applied. An overlapping of the wetted bulbs was observed at the end of the different irrigation experiments. The inter-dripper root-zone had an average water c ontent of 45% and a coefficient of uniformity of 90%. The discharge rate of 2 1/h applied to a 70 cm dripper spacing was characte rised by water losses of 15% due to the significant irrigation duration (8 h). From this study, we reach the following conclusions, specific to the soil t ype and practical culture. 1. The maximum irrigation duration does not exceed 4 h. 2. Two hours durations can be used for the different spacings, each of whic h was characterised by its own discharge rate. (C) 2001 Elsevier Science B. V. All rights reserved.