Estimativa do potencial matricial na frente de umedecimento a partir de características do solo.

Abstract

The Green-Ampt modified by Mein and Larson (GAML) model is one of the most used for the prediction of the water soil infiltration, however, this model has a limitation for obtaining input parameters, such as the potential head at the wetting front (ψm ). This work aimed to obtain the necessary variables for the estimation at the ψm , and to establish a mathematical model that relate the ψm with physics characteristics and the soil hydraulic conductivity ( K0 ). It was used eight columns filled out with three different soils. Accumulated infiltration (I), infiltration rate (Ti), the physics characteristics of the profile and the K0 were determined. The pressure head at the wetting front was calculated through an adjustment in the GAML model, considering the rate of stable infiltration (Tie) as representative of the hydraulic conductivity, and the transmission zone moisture instead of the moisture saturation. Once having the ψm values, soil characteristics and K0 , regression models were adjusted, choosing the best fit by R2 , and the significance of parameters. The best fitted equation was the one which related the ψm with the porosity, the soil hydraulic conductivity and the percentage of silt.