Modelling the suitability of agroecological zones for sorghum cultivation based on GIS multi-criteria analysis in Western Kenya

This study assessed the agroecological suitability of sorghum cultivation using Geographic Information Systems (GIS) integrated with Multi-Criteria Decision Analysis (MCDA), specifically a weighted-overlay approach. Key biophysical factors, such as rainfall, temperature, soil pH, soil texture, slope, elevation, and land use/land cover, were standardised, weighted, and overlaid to generate a composite suitability map. The results showed that 16.9% (221,194.96 ha) of the study area was highly suitable for sorghum cultivation, 74.6% (974,249.53 ha) moderately suitable, 8.4% (109,194.75 ha) marginally suitable, and only 0.1% (668.33 ha) unsuitable. Suitable zones were mainly concentrated in Busia and western Siaya, while moderately suitable areas dominated Kakamega, Bungoma, Vihiga, and Trans Nzoia. Marginal suitability was observed in the high-altitude slopes of Mount Elgon and northern Trans Nzoia, while unsuitable areas were confined to waterlogged lowlands near Lake Victoria. The study concludes that Western Kenya has substantial potential for sorghum expansion, particularly in mid-altitude agroecological zones. It is recommended that sorghum promotion be prioritised in suitable and moderately suitable areas, complemented by soil fertility restoration, improved drought- and cold-tolerant varieties, and integration of GIS-based planning into county agricultural policies.