Hydraulic Parameter Response to Incorporated Organic Matter in the B-Horizon

Abstract

Strip mine reclamation results in excessively compacted B-horizon soils that do not function well as rooting media. Studies have shown that incorporation of organic matter into soil results in improved moisture holding capacity and hydraulic conductivity, reduced bulk density, and increased porosity. Incorporation of organic matter into the top 20 cm of the B-horizon of a mine soil as it is rebuilt can be accomplished without major changes in common mine operations. In a laboratory study, three B-horizon soils were treated with four rates (0, 67000, 135800, 271600 kg/ha) of organic matter and then compacted. The objective was to determine the initial effects of incorporated organic matter on the physical and hydraulic properties of compacted B-horizon reclaimed strip mined soils. The properties considered were bulk density, saturated hydraulic conductivity, porosity, sorptivity, and soil water retention. Bulk density was reduced by up to 25%. Porosity increased up to a point but additional organic matter did not continue to increase porosity. Saturated hydraulic conductivity increased as much as 1400%. The soil water retention curve was affected up to a point by organic matter level but, as with porosity, the effect did not continue with additional organic matter. Sorptivity was not affected by organic matter amendments.