Soil Water Movement and Vegetables Yield Under Subsurface Drip Irrigation with Intermittent Flow.

Soil water flow under intermittent subsurface drip irrigation and its effect on vegetables yields.

Alazba, A.A.; Elnesr, M.N.; and Simunek, J.

The main benefit of drip irrigation is that it applies water in low volumes and relatively small rates to eliminate runoff and deep percolation. However, providing the entire plant water requirement at once during a short time at large time intervals may lead to the occurrence of runoff and deep percolation in some soils. Applying these irrigation amounts at shorter intervals at intermittent rates may resolve this problem. The goal of this study was to evaluate the effects of intermittent drip irrigation in a sandy loam soil planted with two vegetable crops. To achieve this goal, field experiments were conducted during four growing seasons. Additionally, computer simulations using the HYDRUS package were carried out. The field was equipped with automatic controllers for irrigation and a large number of continuous soil-water loggers. The results showed that intermittent irrigation (3 pulses, with OFF time=3 times the ON time) indeed eliminated wasting water through deep percolation and runoff, compared to applying the daily irrigation amount at once. On the other hand, soil-water loggers showed only a small difference between two irrigation techniques with respect to the reduction of deep percolation. The water use efficiency for intermittent irrigation was higher than for the control treatment, but the difference was not statistically significant. Similarly, the total yield of tomatoes and potatoes was not significantly different for the two treatments. HYDRUS simulations showed that intermittent irrigation produced only small differences in the wetting pattern compared to the control treatment during the application time. However, this effect vanishes about 6 hours after irrigation, explaining a negligible effect of the type of irrigation on the crop yield. The intermittent irrigation technology should be tested also in other soil types and with other crops, especially with a higher number of irrigation pulses (the more the better) as indicated by HYDRUS simulations.