Analysis of infiltration in soil columns using the adapted Green-Ampt model. Conclusions for field irrigation

Three types of infiltration tests are analyzed in columns with the same sample of soil to determine the Green-Ampt parameters and guide the characterization using the van Genuchten-Mualem model. In the first type of test, an initial water height was applied, simulating surface irrigation. Results indicate that random variability of initial infiltration and saturated hydraulic conductivity is significant and increases with water height. Additionally, for applying to field irrigation it is recommended to consider preferential pathways infiltration through an initial infiltration. The second type of test maintained a water height between 1 and 2 mm, simulating drip irrigation. This approach showed lower infiltration rates and reduced variability. In the third type of test, a constant average intensity was applied intermittently, considering sprinkler irrigation. In the last two types of tests, parameters were in practice similar, and the differences with the first type of test are attributed to the fact that in these, the larger pores or pathways do not get filled. In all three types of tests, a correlation between parameters was observed. Measurement of matric tensions or depths during infiltration and redistribution phases may help refine parameter estimation to better approximate real conditions. Considering a small hysteresis effect or difference in the redistribution phase with respect to the infiltration phase seems to favor the characterization. Incorporating a minor hysteresis effect during the redistribution phase relative to the infiltration phase appears to enhance characterization. The findings confirm that the Green-Ampt model successfully reproduces experimental tests and is a valuable tool for the rational study of irrigation.