Comparative Assessment of Cocoa Pod Husk Biochar Fortified with NPK Fertilizer Formulations on Kola Seedling Nutrient Uptake and Soil Properties in Ibadan, Nigeria

A greenhouse trial was carried out at Cocoa Research Institute of Nigeria, Ibadan in 2013 to evaluate the effect of cocoa pod husk (CPH) biochar fortified with NPK fertilizer formulations on kola seedling nutrient uptake and soil properties. The treatments consisted of a control, NPK (3 g) + Biochar (5 g), NPK (Liquid – 3 mls/L of water) + Biochar (5 g), Biochar (5 g), NPK (Solid-3 g), NPK (Liquid – 3 mls/L of water). The six treatments were replicated three times in a completely randomized design and data on nutrient uptake of kola seedlings and soil properties were taken for seven months. Results showed that all the fertilizers irrespective of rates of application and types of NPK formulations enhanced the nutrient uptake of kola seedlings relative to control.
The leaf and root nitrogen uptake of kola seedlings was significantly (p<0.05) enhanced as a result of CPH biochar applied singly (T4) or in combination with NPK liquid fertilizer (T3) compared to when biochar was applied with NPK solid fertilizer. The leaf and stem P-uptake of Kola seedlings was not significantly influenced by CPH biochar and NPK fertilizer formulations. Conversely, the P-uptake of root of kola seedlings was significantly (p<0.05) improved as a result NPK (liquid) fertilizer compared to NPK (solid) applied alone. The pH of the soil was significantly (p<0.05) affected due to application of CPH biochar in combination with liquid NPK (T3) and CPH biochar alone (T4) compared to the control and NPK solid (T5). The exchangeable K in the soil was significantly (p<0.05) influenced as a result of CPH Biochar application and NPK fertilizer formulations. CPH biochar alone (T4) significantly (p<0.05) improved the exchangeable potassium in the soil compared to the control. The positive influence of CPH biochar applied either alone or in combination with NPK fertilizers on nutrient uptake of kola seedlings and soil nutrients indicated that integrated use of organic and inorganic fertilizers holds the ace for crop production and soil fertility management in Nigeria. Kola farmers across the growing regions have the privilege of using biochar fortified with NPK fertilizer (liquid) for improved productivity.