Impact of urea-enhanced sulphur fertilizer ‘(11-0-0-75)’ on the growth,protein content and yield of off-season rice in northeast Thailand

Improving rice yield and grain quality in resource-constrained, nutrient-depleted soils remains a pressing challenge forSoutheast Asia’s agricultural sector. This study evaluates the agronomic effectiveness of a novel urea-enhanced sulphurfertilizer (UESF, 11-0-0-75) on the growth, yield, and protein content of the Hom Pathum Thani 1 rice variety cultivatedduring the off-season in Northeast Thailand. Trials were conducted across three districts representing sandy, clay, andmixed soil types in randomized complete block design with four treatments: conventional fertilizer (control), manure withconventional fertilizer, UESF with conventional fertilizer, and a combination of UESF and manure. Results showed thatthe combined treatment of UESF and manure significantly increased rice yield, with gains up to 59.8% in clay soils andnotable improvements in sandy and mixed soils. While the effect on grain protein content was inconsistent across soiltypes, post-harvest soil analysis revealed substantial increases in available sulphate, confirming the fertilizer’scontributionto soil fertility restoration. These findings underscore the potential of UESF, particularly when integrated with organicamendments, as a strategic input for boosting productivity and sustainability in tropical rice systems. The study offersevidence-based guidance for farmers and policymakers aiming to enhance food security while maintaining long-term soilhealth.