Biochar for Soil Management: Effect on Soil Available N and Soil Water Storage

Soil management technologies for climate change adaptation and mitigation are needed to increase and sustain food production in smallholder agriculture while sequestering inert carbon in the soil. In a field studies at Crops Research Institute, Kwadaso-Kumasi Ghana, a control treatment, five inorganic fertilizer combinations (P30K60, N60P30K60, N120P30K60, N180P30K60 and N240P30K60) and four biochar rates + inorganic fertilizer (2 t/ha Biochar + N60P30K60, 4 t/ha Biochar + N60P30K60, 6 t/ha Biochar + N60P30K60 and 8 t/ha Biochar + N60P30K60) were assessed for their effect on soil moisture storage, soil available nitrogen and crop yield. The test crop was okra. Biochar amendments increased soil moisture storage by 14% relative to sole inorganic fertilizer applications. Biochar + inorganic fertilizer relative to sole inorganic fertilizer increased soil available nitrate concentration by 85% at 0-15 cm soil depth but decreased soil ammonium-N by 71%. Compared to control, inorganic fertilizer (P30K60) resulted in more than 100% increase in okra fresh fruit yield. Addition of 60 kg N/ha to P30K60 caused 23% decline in okra fresh fruit yield but showed 60% more okra fresh fruit yield than the control. Inorganic N rates of 120,180 kg N/ha and 240 kg N/ha combined with P30K60 however caused a decline of 74% in okra fresh fruit yield. Biochar + inorganic fertilizer increased okra fresh fruit yield by 100% compared to sole inorganic fertilizer. Biochar, an inert carbon, combined with inorganic fertilizer has tremendous potential to address food insecurity through soil moisture storage and soil N availability.