Effects of Charcoal Production on Soil Physicochemical Properties in Moro Local Government Area of Kwara State, Nigeria

Abstract

Charcoal production is a major economic activity in rural Kwara State, North-Central Nigeria. Given that it generally involves the use of traditional earth kilns, this study was designed to investigate the effects of charcoal production on the physical and chemical properties of soil. Replicate soil core samples were collected within a depth of 0 - 20 cm from 19 charcoal kiln sites (CKS) and 19 adjacent control sites (ACS) across five administrative districts in the study area. These samples were subjected to laboratory analysis to determine their physical and chemical qualities and then t-test was used to statistically compare the CKS and ACS soils. There was no significant difference in soil texture between both sites. However, CKS soil pH and electrical conductivity significantly increased (p < 0.01) by 9.12% and 17.80%, respectively. Conversely, charcoal production led to a significant decrease (p < 0.001) of extractable acidity at a rate of 24.05%. Total organic carbon, organic matter, total nitrogen, carbon to nitrogen ratio, and available phosphorus increased slightly (p > 0.05) due to charred biomass introduced to soils by the process of charcoal production. The CKS cation exchange capacity, Ca and Mg increased significantly (p < 0.0001) by 40.11%, 57.15% and 89.16%, respectively. Charcoal production significantly reduced Fe by 28.54%, while the concentration of other heavy metals remained similar between both sites. The findings showed that charcoal production using traditional earth kilns improves soil physical and chemical properties for agriculture purposes. However, further studies are suggested to understand its effects on vegetation cover and soil biota.