Effectual components on furrow infiltration

Abstract Design, management and evaluation of furrow irrigation depend on how well infiltration characteristics are identified. Furrow infiltration varies with different variables, and modelling of such phenomena is a complex process at field scale. This research was conducted to quantify the contributions of opportunity time ( τ ), water flow depth ( Dg ), initial soil water content ( θi ), flow section area ( A ) and wetted perimeter ( Wp ), as independent variables, on cumulative infiltration (CI) variations using path analysis method; and to develop empirical relationships between field‐wide furrow infiltration and independent variables. Path analysis was used with the aim of scrutinizing direct (DT) and indirect (IDT) effects of five exogenous variables, namely τ , Dg , θi , A and Wp on the endogenous variable of CI. Furrow infiltration was measured by blocked furrow infiltrometers at 56 infiltration sites over a 70 × 130 m field plot. The furrow cross‐sections were taken using a profilometer, whereas flow section area and wetted perimeter were graphically determined from measured cross‐sections. Initial soil water content was obtained by means of the gravimetric method, with drying by the burning alcohol technique in the field. Results revealed that total effects of τ , Dg , θi , A and Wp on furrow infiltration were 0.790, 0.370, −0.359, 0.349 and 0.301; and DT effects of those variables were 92.4, 12.16, 36.50, 42.12 and 14.95% of their total effects, respectively. Consequently, the τ , θi , and A were recognized as the effectual components on the field‐wide furrow infiltration, on the basis of the largest direct effects of the variables. Total and the DT effects of Wp on CI were relatively diminutive compared with other variables. Copyright © 2008 John Wiley & Sons, Ltd.