Biochar Production from Agricultural Waste and Its Effect on Soil Properties and Crop Yield in Benue State

This study investigates the production of biochar from agricultural waste materials and evaluates its effect on soil physical and chemical properties and crop yield under Benue State field conditions. Biochar, produced by pyrolysis of biomass under limited oxygen conditions, has attracted significant research interest as a soil amendment for improving soil water retention, organic carbon content, and nutrient availability in tropical agricultural soils. Benue State's acidic, nutrient-depleted soils could potentially benefit substantially from biochar amendment, but locally calibrated production parameters and field performance data are lacking. This study produces biochar from cassava peels, maize cobs, and rice husks using a locally fabricated top-lit updraft pyrolysis kiln. Biochar characterisation includes proximate analysis, surface area, pH, and elemental composition. A split-plot field experiment at University of Agriculture Makurdi farm tests four biochar application rates (0, 2, 4, and 6 tonnes per hectare) combined with two nitrogen fertiliser levels on maize yield over two seasons. Soil pH, bulk density, water retention, and available phosphorus are measured at the end of each season. Findings reveal that biochar application at 4 tonnes per hectare increases maize yield by 28 percent and soil water retention by 19 percent, with the effect increasing in the second season, consistent with the longer-term stability of biochar carbon. Soil pH increases from 5.3 to 6.1 with 4 tonne biochar application, improving phosphorus availability. The study recommends cassava peel and rice husk biochar as a soil amendment priority for Benue State.

Keywords: biochar, agricultural waste, soil amendment, crop yield, Benue State.