| Research Articles |
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| Soil substrate as a cascade of capillary barriers for conserving water in a desert environment: lessons learned from arid nature |
| Ali Al-MAKTOUMI1*, Said Al-ISMAILY1, Anvar KACIMOV1, Hamed Al-BUSAIDI1, Said Al-SAQRI2, Mansour Al-HADABI1 |
1 Department of Soils, Water and Agricultural Engineering, Sultan Qaboos University, PO Box 34, Al Khoud 123, Muscat,
Sultanate of Oman;
2 EcOman Centre, Petroleum Development Oman LLC, PO Box 81, Muscat, Sultanate of Oman |
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Abstract Interaction between soil pedogenesis, subsurface water dynamics, climate, vegetation and human ingenuity in a desert environment has been found to result in a unique ecohydrological system with an essentially three dimensional sedimentation structure in the bed of a recharge dam in Oman. A 3-D array of silt blocks sand-wiched by dry sand-filled horizontal and vertical fractures was studied in pot experiments as a model of a natural prototype. Pots are filled with a homogenous sand-silt mixture (control) or artificially structured (smart design, SD) soil substrates. Rhodes grass and ivy (Ipomea, Convolvulaceae) were grown in the pots during the hottest season in Oman. Soil moisture content (SMC) was measured at different depths over a period of 20 days without irrigation. SD preserved the SMC of the root zone for both ivy and grass (SMC of around 25%–30% compared to <10% for control, 3 days after the last irrigation). Even after 20 days, SMC was around 18% in the SD and 7% in the control. This, similar to the case of a natural prototype, is attributed to the higher upward capillary movement of water in control pots and intensive evaporation. The capillary barrier of sand sheaths causes discontinuity in moisture mi-gration from the micro-pores in the silt blocks to sand pores. The blocks serve as capillarity-locked water buffers, which are depleted at a slow rate by transpiration rather than evaporation from the soil surface. This creates a unique ecosystem with a dramatic difference in vegetation between SD-pots and control pots. Consequently, the Noy-Meir edaphic factor, conceptualizing the ecological impact of 1-D vertical heterogeneity of desert soils, should be generalized to incorporate 3-D soil heterogeneity patterns. This agro-engineering control of the soil substrate and soil moisture distribution and dynamics (SMDaD) can be widely used by desert farmers as a cheap technique, with significant savings of irrigation water.
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Received: 17 September 2013
Published: 10 December 2014
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| Fund: The authors acknowledge the financial support from the Grant IG/AGR/SWAE/10/02 of the Sultan Qaboos University, Oman. Support from the Ministry of Regional Municipalities and Wa-ter Resources, Oman is appreciated. |
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Corresponding Authors:
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