Growing Onion in Isiolo

Soil suitability analysis based on Isiolo's nutrient profile

Isiolo County is a challenging environment for Onion (soil-match score 28/100) and will need significant amendment before planting. At an average pH of 7.83 the soil sits above Onion's preferred 6–7 range, which can limit uptake of phosphorus and micronutrients. The main gap is nitrogen — measured at N 0.46 g/kg, P 37.4 mg/kg, K 395 mg/kg against this crop's high/high/medium demand — so the fertilizer plan below prioritises closing that deficit. The county's predominantly sandy soils suit Onion, which favours sandy loam. Isiolo receives approximately 350 mm/year — well below Onion's minimum of 500 mm — so supplemental irrigation would be essential for this crop. Onion's full potential is about 6,000 kg/acre (~KES 420,000/acre at KES 70/kg), but at Isiolo's 28/100 suitability a realistic target here is closer to 2,100 kg/acre (~KES 147,000/acre) unless the constraints above are addressed.