Integrating modern soil and water smart technologies for salinity management in theSultanate of Oman

Only a small relative proportion of Oman's land can be used for agriculture, and water resources are scarce and of low quality, limiting the development of the country's agricultural sector. As a consequence of its arid climate, the soils are usually subjected to naturally occurring soil salt accumulation (salinity), frequently accompanied by high pH (alkalinity). Anthropic activities exacerbated this issue and during the last decades, soil quality along the Al-Batinah coast has been progressively deteriorating due to soil salinity and sodicity. Soil salinity represents the main limiting factor to Oman's agricultural production and therefore, a central challenge towards its food security goals. Soil engineering is an emerging and promising approach to mitigate the impact of saline irrigation water through maintaining the ideal threshold levels of soil moisture and salinity in the localized plant root zone. Under this context, soil amendments that can help farmers and other crop practitioners (e.g. home-gardeners and landscapers) to address both soil salinity and alkalinity simultaneously can be useful and strategic nationwide, as well as to all other arid countries with similar problems. The principal investigators and the team of co-investigators involved in this project have been conducting independent research on soil salinity management that has recently highlighted the potential of three possibly complementary innovative technologies: a) modified soil structure with engineered capillary barriers (ECB) mimicking a natural occurring sedimentation pattern discovered in the bed of the reservoir of Al-Khoud dam, for increased water use efficiency and mitigation of salt accumulation; b) the use of elemental sulfur (S0) as a soil amendment to acidify our highly alkaline soils, aiding the desorption and leaching of bases and the speedy reclamation of these highly saline soils; and c) the use of biochar amendments, using local biomass waste, for conditioning the soil properties such as available water and cation exchange capacity, directly related to a swift soil salinity reclamation process. The ECB together with sensor-based automated irrigation technologies was thoroughly studied for saving irrigation water by a strategic fund (TRC, RC/AGR/SWAE/17/01) led by Dr. Said Al Ismaily, with promising effects on decreasing soil salinity and increasing soil health (Menezes-Blackburn et al. 2020). The S0 amendments are currently being researched by a consultancy agreement between Shell Development Oman and SQU (CR/AGR/SWAE/19/02), led by Dr. Daniel Blackburn, and under optimal conditions, has been shown to nearly double soil salt leaching.