Karlen et al. (1990) as cited by Colvin et al. (1990), defined tilth as the physical condition of a soil described by its bulk density, porosity, structure, roughness and aggregate characteristics as related to water, nutrient, heat and air transport; stimulation of microbial and micro-fauna populations and processes; and impedance to seedling emergence and root penetration. Tilth forming process is defined as the combined action of physical, chemical and biological processes that bond primary soil particles into simple and complex aggregates and aggregate associations that create specific structural of tilth conditions.