SOIL HYDRAULIC-PROPERTIES OF RECLAIMED PRIME FARMLAND

Four 6-year-old, prime farmland, surface mine reclamation plots were sampled to determine hydraulic parameters and quantify the effects of hauling method (truck or scraper pan) and the effects of stockpiling. Four depths (10-70 mm, 200-260 mm, 510-570 mm, and 810-870 mm) were sampled with four replications. The hydraulic parameters were soil water retention curve, sorptivity, and water holding capacity. Handling and stockpiling had no effect on any parameter. The profile was characterized with depth. The soil water retention parameters were not related to depth. The bulk density was 1.371 Mg/m3 in the plow layer and 1.729 Mg/m3 in the remainder of the profile. Sorptivity decreased from 1.81 mm/min0.5 in the plow layer to 0.68 mm/min0.5 at 510-870 mm deep. The water holding capacity was a minimum at 510-570 mm deep and increased both in the 810-870 mm layer and the shallower layers to a maximum of 0.309 in the 10-70 mm plow layer. An unsaturated hydraulic conductivity curve was developed but using this curve deeper soils had hydraulic conductivity that was an order of magnitude higher than the 200-260 mm deep layer. As a result, a fundamental flaw in the mathematical model used to develop unsaturated hydraulic conductivity was also demonstrated.