Abstract
Synthetic polymers, such as polyacrylamide (PAM), and biochar are generally used as soil amendments to improve soil properties. This paper explores a laboratory column experiment conducted to investigate the effects of biochar (pyrolysis at 400-450 degrees C) and polymers, with different application rates, on the hydro-physical properties of sandy soil. The experiment evaluated four rates each of biochar (0.0% (C), 2% (B-1), 4% (B-2), 6% (B-3) and 8% (B-4)) and polymers (0.0% (C), 0.2% (P-1), 0.4% (P-2), 0.6% (P-3), and 0.8%(P-4)), as well as a mixture of them. The infiltration rate decreased significantly when a mixture of biochar and polymers was adopted. B-1 showed a decrease of 32.73% while a mixture of 8% (B-4) and (0.8%) P-4 exhibited a decrease of 57.31%. The polymers increased the infiltration rate at low concentrations (P-1 and P-2) and reduced it at high concentrations (P-3 and P-4). The cumulative evaporation decreased significantly for most treatments. B-1 recorded the highest decrease in cumulative evaporation with a percentage decrease of 31.9%. The highest decrease in hydraulic conductivity (Ks) was for B-1. However, the mixture of B-4 and P-4 resulted in the highest increase in soil moisture content at field capacity compared to the control and other treatments. P-4 and the mixture of B-2 and P-2 showed significant (p < 0.05) increases in the percentage of stable aggregate (SA) in fraction size (0.25-0.125 mm). Although the mixture of B-4 and P-4 had the highest increase in soil moisture content, this study recommends using the B-1 treatment on sandy soil in arid environments due to its strong hydro-physical properties and affordability.