Muscat –  Sulphur-treated biochar has shown to increase plant growth and soil fertility in Oman’s saline farmland by up to 200%, offering a potential breakthrough for efforts to reclaim degraded agricultural land. The findings, from a doctoral research conducted at Sultan Qaboos University, also indicate that improved application methods can raise effectiveness by a further 50% compared with untreated biochar.

The study, led by Dr Ahmed bin Rashid al Rubaiei at the College of Agricultural and Marine Sciences, comes as soil salinity threatens more than one million hectares of agricultural land globally. In Oman, about 44% of farmland — mainly in North and South Batinah — is affected, posing increasing risks to crop production and national food security.

Dr Rubaiei examined how combining biochar with elemental sulphur could enhance soil quality in arid, salt-affected environments. While biochar has long been recognised for its ability to improve soil structure and nutrient retention, its performance varies depending on raw materials and pyrolysis temperatures. Its alkaline nature also poses challenges in Oman’s already alkaline soils. Pairing biochar with sulphur, however, has the potential to regulate soil alkalinity while strengthening physical and chemical soil properties.

The research followed a four-stage approach. The first stage analysed the physical, chemical and microbial characteristics of biochar produced from palm waste, mesquite and sewage sludge at three different pyrolysis temperatures. The second stage involved treating the biochar with elemental sulphur and combining it with compost or vermicompost, followed by biological activation over 50 days.

In the third stage, both treated and untreated biochar were tested to assess their influence on the physical, chemical and microbial properties of saline soil. The final stage evaluated their impact under actual agricultural conditions, including salt leaching and plant response when irrigated with saline water.

The findings confirmed that the choice of raw material and pyrolysis temperature are critical to producing effective biochar. Integrating sulphur and organic fertilisers significantly improved soil fertility in arid and salt-affected areas.

The study suggests strong potential for incorporating sulphur-treated biochar into soil-reclamation programmes in Oman, supporting crop productivity and reducing the long-term impacts of salinity.