A four-year monitoring of beerkan infiltration rates in a sandy-loam soil

Long-term investigations on temporal variability of infiltration rates are important for characterizing the porous medium but they are challenging and infrequent. Infiltration rates were measured in a sandy-loam soil by performing 16 beerkan infiltration runs on 14 sampling dates during a nearly four-year period. The means of the initial infiltration rates (i₀) varying by approximately four times, were less variable than the means of both the final (i_f) and the mean (i_med) infiltration rates, varying by 13 and nine times, respectively. The means of all considered parameters decreased as the antecedent soil water content (θ_i) increased but the θ_i effect was stronger for i₀ (coefficient of determination, R² = 0.84) than both i_f and i_med (R² = 0.55-0.68). With reference to these last two parameters, θ_i effects were significant for the lowest measured values (R² = 0.63-0.76) but not for the highest ones (R² = 0.12-0.13). Particularly small i_f and i_med values were obtained in initially very wet soil conditions. The antecedent soil water content can be expected to strongly control infiltration rates in a sandy-loam soil. Sampling the widest possible range of θ_i values is recommended to obtain the most complete information about temporal variability of infiltration rates.