Effect of Energy Input Levels on the Dispersibility of some Alfisols at Samaru, Zaria, Nigeria

Abstract

Recent development of the Water Erosion Prediction Project (WEPP) model, which uses water dispersible clay (WDC) in predicting soil erodibility, has led to increased demand for WDC data. The WDC, total clay (TC), and the WDC/TC ratio of a well-drained Oxic Haplustalf, a moderately well drained Typic Plinthustalf and a poorly drained Aquultic Haplustalf, were determined after shaking at five increasing energy input levels (dispersion periods) of 5 min., 30 min., 1 hr, 2 hrs and 3 hrs. The values of WDC in the Oxic Haplustalf, Typic Plinthustalf and Aquultic Haplustalf, at all energy input levels ranged
from 3 – 18% (mean, 7%); 3 – 29% (mean, 15%) and 9 – 29% (mean, 20%); those of TC, from 20 – 41% (mean, 34%), 11- 37% (mean, 27%) and 17 – 50% ( mean, 40%); and those of WDC/TC ratio, from 7.5 – 90.0% (mean, 23.5), 10.0 – 145.5%
(mean, 61%) and 22.0 – 87.5% (mean, 53.1% ), respectively. Profile mean TC values for the Oxic Haplustalf and Aquultic Haplustalf were at par and both higher (P < 0.05) than for the Typic Plinthustalf. The profile mean values of WDC and WDC/TC ratio were, however, similar for all the soils. Water dispersibility of the soils, i.e., their erodibilty, increased in the
order: Oxic Haplustalf < Typic Plinthustalf < Aquultic Haplustalf, but increasing energy input level significantly (P < 0.01) increased water dispersibility of only the Aquultic Haplustalf. The WDC was negatively correlated with pH and water dispersible silt (P < 0.05) and positively correlated with total nitrogen (P < 0.01).

Keywords: Drainage classes, water-dispersible clay, shaking period, energy input level, erodibility.

Nigerian Journal of Soil and Environmental Research Vol. 7 2007: pp. 60-69