Derivation of Infiltration Equation Coefficients from Early Available Soil Parameters in the Soil with Different Level of SARs

Soil infiltration process is one of the most basic and important parametersin improving the design and management of irrigation systems that accurateestimation will save water consumption in the agricultural sector. Consideringthat the infiltration measurement process is time-consuming and costly. In thisstudy, an equation was extracted through the early available soil parameters toestimate the infiltration rate in saline soils without infiltration measurement. Forthis purpose, the Qazvin Salt Lake District, which has different levels of soilsalinity, was selected. After sampling soil from different parts of the region andsuccessive measurements of salinity, eight samples were gathered with salinitylevels of 1.04, 2.17, 4.7, 7.27, 8.79, 6.3, 13.87 and 20.88 , respectively and finallyanother sample with high salinity as 81.01 was selected. The double rings methodwas used to estimate cumulative infiltration and three replications were performedfor each point. Two general equations based on early available soil variablesincluding Sodium adsorption ratio (), geometric mean soil particle diameter (),soil geometric standard deviation (), Bulk density () and porosity () were usedto calculate the Kostiakov-Lewis equation coefficients by using CurveExpertsoftware and transitional functions. A comparison of the results of the derivationequations with the measured infiltration showed R2 of 0.91 and RMSE of 7.67%that is within the acceptable range. Finally, it can be concluded that the obtainedequations from the early available soil parameters has properly good estimationof infiltration and its high performance will save time and cost in the complexinfiltration measurement processes.

Keywords:

Infiltration , Double ring , Soil salinity , Kostiakov-Lewis coefficients , Erarly available soil parameters