Growing Green Grams in Nyandarua

Soil suitability analysis based on Nyandarua's nutrient profile

Nyandarua County is a challenging environment for Green Grams (soil-match score 31/100) and will need significant amendment before planting. At an average pH of 5.38 the soil is moderately acidic, below Green Grams's preferred 5.5–8 range; agricultural lime will lift pH and unlock phosphorus the crop cannot otherwise access. Nitrogen (1.28 g/kg), phosphorus (14 mg/kg) and potassium (166 mg/kg) all meet Green Grams's requirements, so a maintenance fertilizer programme is enough. Green Grams prefers sandy loam soils, while Nyandarua is largely clay, so drainage and organic-matter management matter more here. At 2300 m, the county sits above Green Grams's preferred altitude ceiling of 1800 m, where frost risk and cold nights reduce the crop's productivity. Green Grams's full potential is about 400 kg/acre (~KES 48,000/acre at KES 120/kg), but at Nyandarua's 31/100 suitability a realistic target here is closer to 155 kg/acre (~KES 18,600/acre) unless the constraints above are addressed.