COMPARATIVE EFFECT OF WASTE MATERIALS ON CHEMICALLY DEGRADED SOIL IN SOUTH WESTERN NIGERIA

Abstract

The present study examined the comparative effect of addition of calcium carbonate and waste materials with liming potential on the soil pH and other soil chemical properties of chemically degraded sandy loam soils (Ultisol, Iwo series). Soil samples (0-15 cm) were collected from two sites at the Teaching and Research Farm, Obafemi Awolowo University, Ile-Ife, Nigeria. The waste materials used were eggshell powder (ESP) and biochar (ESB), calcium carbide waste (CCW), and wood ash (WA). An assay of the wastes showed relatively high calcium carbonate equivalent.  An incubation study was undertaken in the laboratory for four weeks with soil samples from the two soil types, treated with 0.25, 0.5 and 0.75 g of waste materials per 100 g soil. The results of physical and chemical properties revealed a low fertility soil. For example, the soil pH, soil organic matter, were 5.6, 1.27% and 5.3, 2.5% for the two soil types respectively. The calcium carbonate equivalence of ESP, ESB, CCW and WA were 103, 101, 123 and 59% respectively. Significant increase in soil pH and concentrations of some basic cations were observed after the addition of the waste materials. In addition, manganese and exchangeable acidity were significantly reduced in all the treated soils compared with the control, except soil treated with WA which could be attributed to low calcium carbonate equivalence as compared to other liming materials used in this study. The study established effectiveness of the waste materials used as good alternatives to the use of pure calcium carbonate and concluded that, any of these wastes (eggshell, wood ash and calcium carbide waste) can be used as an alternative source of liming for remediation of chemically degraded soils.