Growing Onion in Isiolo
Soil suitability analysis based on Isiolo's nutrient profile
Generally not ideal — Isiolo is poorly suited to Onion. Isiolo's soil (pH 7.83, alkaline) gives Onion a suitability score of 28/100. Match fertilizer to Isiolo's nitrogen and phosphorus levels for the best result.
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. On ShambaIQ's soil-match model, Onion is the #33 soil match of the 106 crops we assess for Isiolo County. 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.
Better matched to Isiolo's soil: Sisal, Aloe Vera, and Green Grams — each scores higher on the same soil.
Soil & climate match
| Factor | Isiolo soil | Onion needs | Status |
|---|---|---|---|
| pH | 7.83 | 6–7 | Adjust |
| Nitrogen | 0.46 g/kg | min 1.2 g/kg | Low |
| Phosphorus | 37.4 mg/kg | min 20 mg/kg | OK |
| Potassium | 395 mg/kg | min 150 mg/kg | OK |
| Rainfall | 350 mm | 500–1,000 mm | Low |
| Altitude | 900 m | 0–2,000 m | OK |
Planting calendar for Isiolo
Long Rains· March–May
Short Rains· October–DecemberMain season here
Dry Season· January–March
Top dressing guide
Isiolo's nitrogen (0.46 g/kg) is 38% of the 1.2 g/kg Onion needs, so the standard 0.5 bags/acre is raised to 0.75. Split it across two applications to limit leaching.
Recommended seed varieties
No variety in our list is specifically rated for Isiolo's 900 m altitude and 350 mm rainfall, so all 2 are shown. Confirm with your agrovet before buying.
Economics
Fertilizer prices
Green = subsidized · (Commercial) per 50kg bag