Clay Dispersion of Selected Aeolian Soils of Northern Nigeria in Relation to Sodicity and Organic Carbon Content

Abstract

Studies on dispersive behavior of semiarid soils upon application of water are very important since such soils are often irrigated and followed by dry periods. The outcome of such treatments on the soils affect the soil physical properties adversely leading to wind erosion. The objective was to determine the water-dispersibility of the semi-arid soils and the contribution of their electrolyte and soil organic carbon (SOC) content in their dispersibility. The soils are mainly Cambic Arenosols (FAO) or Typic Xeropsamments (USDA Soil Taxonomy), kaolinitic with few smectite and low in cation exchange capacity. Ten topsoil samples from 0-20 cm depth for this study were collected from the aeolian zones of northern Nigeria. Total clay content of the soils varied between 6 and 16% while water-dispersible clay was low (4-8%) and a reflection of the low total clay content. Organic carbon (OC) correlated significantly with WDC ( r = 0.57 ) while exchangeable Na + also correlated significantly with total clay (DC) and WDC ( r = 0.84, 0.67) respectively Organic carbon, and exchangeable Na + , influenced water-dispersible clay content while exchangeable sodium percentage (ESP), exchangeable sodium ratio (ESR) and electrolytic conductivity (EC) correlated significantly with clay-dispersion ratio (CDR).