The stability of steady, vertically upward and downward flow of water in a homogeneous layer of soil is analyzed. Three equivalent dimensionless forms of the Richards equation are introduced, namely the pressure head, saturation, and matric flux potential forms. To illustrate general results and derive special results, use is made of several representative classes of soils. For all classes of s...

Predictions of growth are important factors that contribute to the profitability of an operation in poultry production. Modern commercial hybrids have a higher body growth in comparison with the local purebreds. However a niche market for meat and egg poultry production needs to be established using local purebreds to promote biodiversity. The aim of this study was to model the growth response ...

Capillary pressure-saturation-relative permeability relations described using the van Genuchten and Mualem models for non-uniform porous media lead to numerical convergence diiculties when used with Richards' equation for certain auxiliary conditions. These diiculties arise because of discontinuities in the derivative of speciic moisture capacity and relative permeability as a function of capil...