Residual effects of corncob biochar on tropical degraded soil in central Uganda.

Background: The residual effects of biochar are yet to receive adequate research attention in Sub-Saharan Africa despite the assumption that the positive effect of biochar may last longer on degraded tropical soil. Hence a field experiment was conducted to assess the residual effects of biochar, farmyard compost and NPK fertilizer applications on a Ferralsol in central Uganda. The field used for the study was previously used to conduct experiments for two seasons to assess the contribution of corncob biochar to the chemical properties of this highly degraded tropical soil. Result: The co-applied biochar with compost and NPK fertilizer significantly (p < 0.05) increased some soil chemical properties such as soil pH, available phosphorus, soil organic carbon, and potassium than the control. The co-applied biochar with compost also significantly (p < 0.05) increased the soil pH and effective cation exchange capacity compared to the solely applied compost and NPK fertilizer. Collard plant height, canopy, stem girth, number of leaves, leaf length, and total biomass were significantly (p < 0.05) higher in the biochar amended soil than the unamended soil. Conclusion: It was concluded that the addition of biochar with compost and NPK fertilizer had a significant residual effect on degraded tropical soils than solely applied NPK and compost. [ABSTRACT FROM AUTHOR]