Estimates of tillage effects on saturated hydraulic conductivity

Soil saturated hydraulic conductivity (K,) is needed to simulate many water transport related processes in soil, such as water erosion, surface runoff, and water supply to plants. In this study, data reported in the literature relating ~ to tillage practices published during the past 25 years were compiled, pooled, and regressed to obtain relationships between ~ and soil variables. The data showed that soil bulk density (Pb) is a major factor influencing ~ for general tillage conditions. When specific tillage treatments are considered, K, is principally related to soil organic matter (OM) for no-till soil; ~ is also affected by the clay and silt contents for plowed soils. Based on data compiled from the literature, several equations that incorporate tillage practice and basic soil variables were proposed to estimate Ks• These equations were evaluated with field data from Quebec soils where the dominant textures were sandy. Large differences in K, values between the field data and the prediction values were found due to variable soil characteristics and tillage conditions. Evaluations of three previously-published models for K, prediction were also performed using the Quebec field data and none of them was in close agreement with the measurements. However, results from Campbell's model were significantly correlated to the field data, although the model under-predicted ~. This model was calibrated with the measured Quebec data used in this study for prediction of field Ks for sandy soils.