Evaluation and modelling of furrow infiltration for uncropped ridge - furrow tillage in Loess Plateau soils

The soil water dynamic process is critical for the design, management, and evaluation of ridge–furrow tillage in the semi-arid region of the Loess Plateau. The aim of this study was to determine the effectual infiltration variables, to evaluate the performance of four classical infiltration models, and to investigate the effect of those variables on the infiltration characteristics in a ridge–furrow configuration. Sixteen experimental treatments with two replications were conducted to monitor furrow infiltration in four types of Loess Plateau soils. The path analysis method was applied to quantify the effects of variables—opportunity time (T), initial soil water content (Q), bulk density (P), flow section area (S), and wetted perimeter (Wp) as independent variables—on cumulative infiltration (I). The results revealed that the direct effects of variables Wp, P, T, Q, and S on I were 0.751, –0.649, 0.291, –0.251, and –0.123, respectively. Variables Wp and P were the effectual components of furrow infiltration. The direct effect and total effect of Q on I were relatively minor compared with the other variables. The performance of four infiltration models (Philip model, Kostiakov–Lewis model, Kostiakov model, and Horton model) was investigated on the basis of evaluation indices. The Kostiakov–Lewis infiltration model with three parameters provided the best description of the relationship between cumulative infiltration and time. The influence of Wp on the constant coefficient k of the Kostiakov–Lewis model was significant. A furrow infiltration model taking Wp into consideration was developed. Validations in different Wp of two other soil types indicated that the soil water infiltration characteristics could be effectively simulated by the effectual variable based model for an uncropped ridge–furrow system. The information obtained from this research is useful in designing irrigation schemes and field management for ridge–furrow tillage.