HYDRAULIC CONDUCTIVITY AND SOIL-WATER DIFFUSION AND ITS RELATIONSHIP TO GYPSUM AND CLAY CONTENT OF SOILS TREATED WITH PEAT-MOSS AND POLYMER

Abstract

An experiment was conducted to estimate hydraulic conductivity, soil-water diffusion, and its relationship to gypsum and clay content of soils treated with peat-moss and polymer. Two soils were used, the first containing 410 gm. kg-1 of gypsum and the second containing 435 gm. kg-1 clay. They were mixed in five ratios, gypsum ranged between 410 and 46 gm. kg-1 and clay from 0 to 435 gm. kg-1. The five soils were treated with peat-moss and polymer. Soils were packed into plastic tubes and exposed to three wetting and drying periods. The saturated hydraulic conductivity and hydraulic conductivity in a wide range of structural tension were estimated using Jackson equation 1977 equation and soil water diffusion as a function of hydraulic conductivity values and the slope of the moisture tension curve.The results showed that the relationship between K and D with 𝛳 is a positive correlation, and with ѱ is an inverse correlation. Their relationship was also positive with the proportions of gypsum.  The value of K increased from 81.7 cm.day-1 to 137.8 cm.day-1 and the value of D from 7834.8 to 11708.4 cm2.day-1, when the percentage of gypsum increased from 46 to 410 g. kg-1 sequentially for soil not treated with conditioners within tension limits that approached zero. The values of K and D decreased when treating the soil with peat-moss and polymer, and the most effective treatment in reducing the values of K and D was a mixture (polymer 2% + peat-moss 1%). The values of K and D remained close to zero with medium to high tension and also with 𝛳 from medium to few, they did not increase effectively except when 𝛳 approached its upper limits and with low tension, and its increase was exponential within these ranges.

Keywords

• hydraulic conductivity
• gypsum
• clay
• peat-moss
• polymer