Humidity-determined soil parameters on the field capacity of irrigable areas of the Brazilian semi-arid tropics.

Abstract

Using a sequential mathematical model, a simulation was made of the principal soil parameters: estimation of humidity at the permanent wilting point (PWP) (1.5 MPa) and water retention curves by means of the corresponding soil humidity at the field capacity point (FCP). Using response surface techniques, textural classifications based on total water availability (TWA) of the soil (m 3/ha per cm) were obtained, facilitating the practical application of the results. The model developed, based on the analysis of 4,288 samples, allowed an estimate to be made of related variables, with a degree of significance superior to 0,01. Field validation proved to be applicable to farmers in irrigable arcas who still do not have access to information obtained in the laboratory.