Growing Pyrethrum in Tharaka Nithi

Soil suitability analysis based on Tharaka Nithi's nutrient profile

Tharaka Nithi County is a challenging environment for Pyrethrum (soil-match score 31/100) and will need significant amendment before planting. At an average pH of 4.99 the soil is strongly acidic, below Pyrethrum's preferred 5–6.5 range; agricultural lime will lift pH and unlock phosphorus the crop cannot otherwise access. The main gap is phosphorus — measured at N 1.23 g/kg, P 19.6 mg/kg, K 211 mg/kg against this crop's medium/high/medium demand — so the fertilizer plan below prioritises closing that deficit. The county's predominantly sandy loam soils suit Pyrethrum, which favours loam. At 1100 m, the county sits below Pyrethrum's preferred altitude range (1800–3000 m), which limits yield potential due to heat stress. Pyrethrum's full potential is about 500 kg/acre (~KES 140,000/acre at KES 280/kg), but at Tharaka Nithi's 31/100 suitability a realistic target here is closer to 194 kg/acre (~KES 54,320/acre) unless the constraints above are addressed.