Effect of Biochar Type and Rate of Application on Maize Yield Indices and Water Use Efficiency on an Ultisol in Ghana

In an integrated approach to cut-down on inorganic fertilizer use by smallholder farmers for agricultural production through the use of biochar, a split-split plot experimental design with three replications was carried to determine the effect of biochar from three different feedstock (corn cob, rice straw and cocoa pod husk) applied at two different rates of the feedstock (2.5 t ha-l and 5 t/ha) with three application rates of Nitrogen, Phosphorus and Potassium (N-P-K) as inorganic fertilizer (90-60-60, 45-30-30 and 0-0-0) on maize growth and yield as well as soil chemical properties. The main plots of the experimental design were allocated to the biochar types while the Sub-plot was allocated to the biochar rates. The Sub-sub-plot went for the inorganic fertilizer rates. The maize seeds were sown at spacing of 80cm between rows and 40cm between plants. Three seeds were sown per each stand which was later thinned to two plants two weeks after planting. Urea, Triple superphosphate and Muriate of Potash were used as the sources of inorganic nitrogen, phosphorus and potassium (N-P-K) respectively. The P and K were applied once two weeks after planting while the N was split applied. One third of the application rate of nitrogen was applied two weeks after planting and the remaining two thirds applied six weeks after planting. Soil samples were collected from 0-20cm depth before planting (one composite sample from the experimental site) and at harvest (from each treatment plot) to evaluate the effect of the different amendments on different soil chemical properties notable N, P, K, CEC, and pH. The quantity of biochar application had pronounced effects on maize grain yields where higher application rates (5 t/ha) showed superior performance to 2.5 t/ha.