|Soppe, R. - ALTERRA-ILRI|
Submitted to: National Salinity Engineering Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 14, 2004
Publication Date: November 9, 2004
Citation: Ayars, J.E., Soppe, R.W. 2004. Integrated water management for saline drainage water disposal. National Salinity Engineering Conference Proceedings. Engineers Australia, Engineering Salinity Solutions, (no volume), pp 9-14. Interpretive Summary: Disposal of saline drainage water from irrigated agriculture is required to maintain a sustainable system. However, the volumes of drainage water that are currently being discharged are in excess of what is actually needed. Methods available to reduce the drainage water volume include: improved irrigation management; using drainage water for irrigation; integrating the management of irrigation and drainage system to induce crop water use from shallow ground water; and the sequential use of drainage water for irrigation prior to disposal. Since the plant based systems require salt tolerant crops to be effective, these alternative are often not cost effective because many salt tolerant crops often have lower economic values. The economics of plant based disposal would be improved if high value crop could be used. This study evaluated the impact on yield and quality of alfalfa irrigated with saline water. The results showed a decrease in yield compared to alfalfa irrigated with good quality water but a significant increase in quality when grown using saline water. Further study will determine whether these results can be sustained for several years.
Technical Abstract: Disposal of saline drainage water from subsurface drainage systems is a major problem limiting the sustainability of irrigated agriculture. The first step in solving this problem will be to reduce the drainage volume needing disposal. This can be accomplished by integrated management of the irrigation and drainage systems to reduce deep percolation losses from irrigation and to induce crop water use from shallow ground water. Irrigating crops using saline drainage water will also contribute to reducing the drainage water volumes. A third alternative is the sequential use of saline drainage water on progressively more salt tolerant crops to reduce the drainage volume and be the ultimate disposal site. This has been called sequential biological concentration (SBC). There is a need for economic crops to be included in the SBC system. Alfalfa is a potential crop and this study looks at the impact on yield and quality of alfalfa irrigated with saline water. The data show a progressive decline in the yield over the season when a single irrigation of saline water is used between cuttings. There was also a decline in yield when two saline water applications were compared to two irrigations with low salinity water. However, the additional stress associated with irrigating with saline water resulted in very high quality forage for dairy cows.