Effect of organic and inorganic fertilizers on growth, yield and nutrient content of bird chilli (Capsicum frutescence)

Four rates (0, 20, 40, 60 t/ha) of organic fertilizer (processed poultry manure) and three rates of inorganic fertilizer (0, 2 and 3 t/ha) were evaluated on bird chilli grown on an upland clay soil. Significant effects of processed poultry manure (PPM) and inorganic fertilizer (NPK) rates on yield were obtained. Interaction effects between PPM and NPK were not significant. Yield increased significantly from 6.46 t/ha at zero fertilizer to 15.49 t/ha at 20 t/ha PPM + 2 t/ha inorganic fertilizer (N:P2O5:K2O: MgO = 12:12:17:2). Regression analysis showed a significant quadratic response to the inorganic fertilizer, represented by the equation Y = 9.1455 + 5.0848x – 1.3292x2, where Y = yield in t/ha and x = fertilizer applied in t/ha. The optimum rate of inorganic fertilizer was 1.91 t/ha. Yield response to organic fertilizer as the sole nutrient source was quadratic, represented by the equation Y = 6.0813 + 0.1861x – 0.0018x2, where Y = yield in t/ha and x = organic fertilizer in t/ha. The optimum rate of organic fertilizer was 52 t/ha. Fertilizers had no significant effect on fruit weight, but had a significant effect on fruit length. Fruit weight ranged from 0.76–0.89 g and fruit length ranged from 3.8– 4.5 cm. Nutrient contents did not differ significantly, except for fruit Ca, Fe and Mn and leaf Mg and Mn. The mean fruit macronutrient contents were 2.38% N, 0.46% P, 5.22% K, 0.18% Ca and 0.24% Mg, and the mean fruit micronutrient contents were 27 mg/kg B, 13 mg/kg Cu, 76 mg/kg Fe, 8 mg/kg Mn and 27 mg/kg Zn. Mean leaf macronutrient content were 4.81% N, 0.36% P, 5.48% K, 1.62% Ca and 0.46% Mg, and mean leaf micronutrient contents were 44 mg/kg B, 17 mg/kg Cu, 284 mg/kg Fe, 17 mg/kg Mn and 47 mg/kg Zn. Most soil chemical properties improved with increasing rates of organic fertilizer.