Agricultural lands across the globe are increasingly threatened by soil salinity, with over one million hectares affected by degradation due to this phenomenon. In the Sultanate of Oman, about 44% of agricultural land has been impacted by salinity, particularly in North and South Al Batinah. This poses a direct threat to crop yields and, consequently, to national food security.

This issue has grabbed the attention of Dr. Ahmed Rashid Al-Rubaiai, who conducted research within the PhD programme at the Department of Soils, Water and Agricultural Engineering, College of Agricultural and Marine Sciences. His study focused on the synergistic effects of using biochar combined with elemental sulphur for reclaiming saline soils.

While biochar has already been proven effective in improving soil quality, its physical and chemical properties vary depending on several factors, including feedstock type and pyrolysis temperature. Furthermore, its alkaline nature can be another challenge in Oman’s already alkaline soils. Combining biochar with sulphur presents an effective strategy to control soil alkalinity and improve both physical and chemical soil properties, making it a promising solution for supporting sustainable agriculture in arid and saline environments.

To address the challenges of salt-affected land, the researcher designed an advanced study carried out in four main phases. The first phase was focused on analysing the physical, chemical, and microbial properties of biochar produced from three available sources  palm waste, mesquite plants, and sewage sludge compost at three different pyrolysis temperatures. In the second phase, the biochar was enhanced for use in arid soils by treating it with elemental sulphur, mixing it with organic or vermicompost, and allowing it to undergo biological activation for 50 days. The third phase evaluated the impact of both treated and untreated biochar on the physical, chemical, and microbial properties of saline soil. The final phase applied the biochar agriculturally to assess its effect both treated and untreated on salt leaching and plant response under saline irrigation conditions.

The study concluded that the choice of feedstock and pyrolysis temperature are key factors in producing effective biochar. Additionally, combining biochar with sulphur and organic fertilisers constitutes a promising and sustainable approach to improving soil fertility in arid and saline lands.

Results showed that biochar treated with sulphur increased plant growth and soil fertility by up to 200%. Furthermore, modifying the direct application technique led to an additional improvement of 50% compared to untreated biochar.

These findings highlight the significant potential of using sulphur-treated biochar in soil reclamation programmes in the Sultanate of Oman. This mixture has been proven effective in enhancing soil fertility, boosting crop productivity, and significantly reducing the impacts of salinity.