Optimization of Modern Irrigation for Biosaline Agriculture PDF

Keywords

Optimization, biosaline agriculture; trickle, sprinkler; leaching ratio

Abstract

Supplemental irrigation water is a must to offset the water requirement to produce profitable crops in most arid and semiarid zones, where fresh water resources are insufficient to meet the pressure of irrigated agriculture. This necessitates the use of poor quality water resources These waters if not properly managed and used can cause serious soil related problems (salinity, sodicity, destruction of soil structure), in addition to decline in crop yields. Biosaline agriculture (using saline water on saline soils to grow salt-tolerant crops) becomes the only option for the farmer when both soil and water resources are saline and the water resource is scarce. In this regards key design considerations must be taken into account when irrigating with salty waters to optimize water uses and to reduce subsequent soil salinity development Sprinkler irrigation systems are commonly used in irrigation of large-scale agricultural production systems. However, they tend to concentrate salts on the leaves of plants. For this reason discharge and degree of overlap between consecutive sprinkler heads, are key design parameters when applying salty waters. Trickle irrigation is the most efficient system and is gaining importance in the GCC countries in agriculture and landscape irrigation. The objective of this study was to optimize modem irrigation systems through development of design standards for drip (emitters spacing) and sprinkler irrigation systems (single head jet and overlapping) by applying saline water The effect of emitter spacing (drip) and overlapping (sprinkler) were tested for the formation of salt contours in soil. The leaching ratio (LR) is the overall soil salinity within the rhizosphere divided by the average irrigation water salinity. In this study LR is used to evaluate the effectiveness of irrigation systems in developing soil salinity. From the present investigations it is concluded that when using saline water for irrigation, the soil salinity development can be significantly reduced by decreasing emitter spacing i.e. an ECe of 26. 90 and 126 dS/m was developed with 25, 50 and 75 cm emitter spacing respectively. Micro sprinklers are more effective in terms of leaching capability as compared to impact sprinklers. Overlapping in sprinkler irrigation reduced the evaporation compared with single jet where no overlapping was made. This has a direct effect on soil salinity development. Wind has a significant effect on the water distribution (sprinkler experiment) and subsequent salinity development and can cause long-term salinity problems. Windbreak can offer solutions to this effect.