Growing Onion in Nyandarua

Soil suitability analysis based on Nyandarua's nutrient profile

Onion can be grown in Nyandarua County, but the soil scores 50/100 and needs targeted management to reach full potential. At an average pH of 5.38 the soil is moderately acidic, below Onion's preferred 6–7 range; agricultural lime will lift pH and unlock phosphorus the crop cannot otherwise access. The main gap is phosphorus — measured at N 1.28 g/kg, P 14 mg/kg, K 166 mg/kg against this crop's high/high/medium demand — so the fertilizer plan below prioritises closing that deficit. Onion prefers sandy loam soils, while Nyandarua is largely clay, so drainage and organic-matter management matter more here. Onion's full potential is about 6,000 kg/acre (~KES 420,000/acre at KES 70/kg), but at Nyandarua's 50/100 suitability a realistic target here is closer to 3,750 kg/acre (~KES 262,500/acre) unless the constraints above are addressed.