Effect of Sand Mixing on Clay Structural Parameters

— Clay-sand mixing experiment was conducted in order to assess the effects of sand mixing on the structural parameters of clay soil (vertisol) obtained from Lake Geriyo, Yola, Adamawa state. Five levels of sand-mixing using 250g, 150g, 100g, 50g and 0g sand per kg of clay soil were used. Saturated pastes of the mixtures were allowed to dry in tray for three weeks after which the cracking pattern and the number of cracks of the dry clay-sand mixture were observed qualitatively. Quantitative determination was made of the aggregate size distribution, clod bulk density and aggregate stability. The results of these determinations have showed that fine sand mixing has no significant effect on the number of aggregate larger than 2mm, while the aggregate size less than 0.5mm was influenced by the coarse sand-mixing. Clod bulk density decreased with increase in the levels of sands mixed. Aggregate stability as assessed by wet sieving method increased with increase in sand addition. Moisture content of sand-mixtures at field capacity decreased with increased in both fine and coarse sand additions while significant (p<0.05) treatments effect was observed due to coarse sand addition on saturated moisture content of the soil as 50 and 100g coarse sand followed (0g sand) no sand addition treatment. With this, it can be deduced that, additions of sand materials influences structural parameters and water retention properties of clay soil and should therefore be encouraged in clay soils of semi-arid environments.