Evaluation of different infiltration models under long term conservation agricultural practices

A study was undertaken to evaluate the long term effect of different conservation agriculture (CA) practices on infiltration characteristics of soil and empirical Kostiakov model and physical process based Green and Ampt, and Philip models were used to predict infiltration rates. The performance of different models was evaluated using statistical criteria. Six treatments were selected, viz. conventional tillage (CT), permanent narrow bed (PNB), permanent narrow bed with residue (PNB+R), permanent broad bed (PBB), permanent broad bed with residue (PBB+R) and zero tillage (ZT). Results showed that the initial infiltration rate was highest (22.93 cm hr(-1)) in PBB+R and was lowest (7.64 cm hr(-1)) in CT. Cumulative infiltration of all the treatments followed the order: PBB+R>PNB+R>PBB>PNB>ZT>CT. The 'a' values of Kostiakov model was 197.5 and 310 % higher in PBB and PBB+R as compared to CT. Steady state infiltration (ic) of Green and Ampt model was found to be highest (8.47 cm hr(-1)) in PBB+R and was lowest (1.88 cm hr(-1)) in CT. Sorptivity (S) parameter (cm hr-0.5) of the Phillip model was found to be highest in PNB+R (67.33) followed by PBB+R (43.61) and lowest in CT (16.23). Highest saturated hydraulic conductivity ('K') value of Phillip model was obtained in PBB+R followed by PBB>PNB>PNB+R>CT. After checking the model performance, it has been found that simple empirical Kostiakov (1932) infiltration model represented the infiltration rate and time relationship in a better way and characterized the best fit with the experimentally observed field infiltration data.