Mine Soil Properties, Reconstruction Protocols and Row-Crop Productivity of Reclaimed Mineral Sands Mines In Virginia.

Over 1500 ha of prime farmland soils in the Coastal Plain of Virginia have been disturbed to date by mining for heavy mineral sands (ilmenite and Zircon) since 1997 and an additional 2500 ha in the region contain economic reserves.  Early reclaimed lands were hampered by excessive compaction, poor drainage and low pH + available P.  Detailed morphological study of > 40 mine soil pedons revealed significant root limiting densic layers and strong textural stratification. The mine soils primarily classify as Typic Udorthents and Typic Udifluvents, but occasional Typic Dystrudepts have been noted.  Between 2005 and 2008, a corn-wheat/double crop soybeans rotation was managed on plots in a randomized complete block design with 4 replications of 4 treatments: 1) LBS-CT – lime-stabilized biosolids (78 Mg/ha) with conventional tillage, 2) LBS-NT – lime-stabilized biosolids (78 Mg/ha) with no tillage, 3) TS – 15 cm of topsoil replacement, and 4) C – control (tailings).  All treatments were ripped, limed, and fertilized.  Two additional study sites, managed similar to the treatment plots, included a compacted (no ripping) area (COMP) and a nearby unmined prime farmland field (UM). Overall, the two LBS treatments produced significantly higher yields than the TS or C treatments.  Yields from all four treatments exceeded long-term local county averages but were typically 25 to 40% lower than yields from local unmined soil. Relatively low COMP yields illustrated the need for ripping and chiseling to improve physical conditions of these mine soils.