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Abstract. Accurate estimation of soil organic carbon (SOC) is needed in many fields of science including ecology, soil science and global climate change. Loss on ignition method (LOI) of estimating SOC has been proposed as rapid, accurate and cheap method but it has some limitations. Walkley-Black method is also widely used. For this study, 12 soil samples from 0-15 cm depth were collected from four sites of the Crop Plantation Section of the Department of Crop and Soil Sciences, KNUST. The amount of SOC (%) estimated by LOI and W-B methods, and clay content were used to develop simple and multiple linear regression equations to describe their relationships. The highest estimate of SOC (3.28%) was produced by Loss on ignition method, whereas W-B gave lower estimates with 1.35% being the highest produced by this method. The coefficient of determination, R 2 , for the equations ranged from 0.35 to 0.84. Very weak relationship was observed between LOI and W-B as evidenced by R 2 value of 0.35. The clay content had a strong positive correlation (r = 0.70, p < 0.001) with LOI and gave R 2 value of 0.49, depicting a moderately strong relationship. However, multiple linear regression analysis of clay content and LOI values as independent variables and W-B values as the dependent variable provided reliable estimates of SOC with R 2 value of 0.84. Results from t-test analyses showed that estimates of the constants and coefficients of all variables in the equations were significantly different.

The infiltration rates of variable soils were scaled using factors derived from the steady state infiltrability (Ko) and the saturated hydraulic conductivity (Ks) based on the similar media theory and dimensional analysis. Infiltration rates were successfully scaled when the characteristic scaling infiltration rate equations were formulated through combination of the similar media theory and dimensional analysis. This study disproved the earlier notion that to successfully scale variable infiltration measurements, both sorptivity and steady state infiltrability were required. Thus, the study revealed that using the saturated hydraulic conductivity as a substitute for the steady state infiltrability could predict and scale infiltration rates more accurately. The study further highlighted the importance of the scaling factor (α) in any characteristic equation supposedly to have been developed from the similar media theory. Invariably, the ability of any characteristic scaling equation containing no scaling factor to scale variable infiltration measurements successfully could be fortuitous and not evolved from the similar media theory.