COMPACTION EFFECTS ON MINELAND SOIL QUAUTY

Abstract

Management of water is vital to sustenance of biomass production and environmental quality of reconstructed minelands in semi-arid North Dakota. Since water resides and moves through soil pores, quantification of soil pore characteristics is a key to evaluate soil quality for reclamation success. We measured field saturated hydraulic conductivity (K) by double-ring ponded infiltration method on 26 pre-mine and postmine profiles. The same profiles, each installed with a neutron probe access tube and a set of five tensiometers, were used to monitor post-infiltration redistribution of water by measuring volumetric water contents and matric potentials with time. An empirical equation was fitted to the soil water retention data to derive proportional distribution of various sizes of pores, maximum water capacity, median pore size, and a depth weighted pore index ({Omega}) to compare efficiency of each profile to transmit and retain water. The undisturbed pre-mine soils showed high {Omega}`s and high proportion of effective pores ({epsilon}) with radii > 5 {mu}m. The reclaimed mineland profiles show low {Omega} and general deficiency of pores effective in transporting water to deeper depths. The pooled data from the premine and postmine soil profiles included in this study show that K increased linearly with {Omega} andmore » {epsilon}2. We recommend that the K - {epsilon} relationship be further evaluated by measuring infiltration and pore size distribution from various locations under different management conditions. If feasible, the easily measurable, profile scale, K - {epsilon} relationship provides a quantitative tool to evaluate soil quality of premine and reclaimed soils.« less