Reclamation of Prime Farmland Following Mineral Sands Mining in Virginia

Abstract

Significant deposits of mineral sands were discovered in Virginia's Upper Coastal Plain in 1989. The Old Hickory Deposit is the largest ore body in the state (>2000 ha) and supports a productive rowcrop agriculture on prime farmlands. Field experiments were installed on pilot-scale (25 m X 60 m) mining pits in the late summer of 1995 and replicated on an adjacent undisturbed area. Half of each mining pit was topsoiled (25 cm) while the remaining half was left as either (1) mixed tails/slimes or (2) re-graded subsoil over tails/slimes to simulate various pit closure scenarios. Both non-topsoiled areas received 112 Mg/ha of yard waste compost as a soil building amendment. The entire area was ripped/disced to ameliorate compaction and incorporate lime and fertilizer additions. The experiment was cropped through a wheat/soybeans/corn/cotton rotation over the 1995 to 1998 growing seasons. Taken as a whole, these combined results clearly indicate that mining and reclamation of these prime farmlands will lead to a substantial decrease in rowcrop productivity, at least over the initial years following pit closure and reclamation. For the rotation studied, post-mining productivity was estimated by this experiment to be reduced by 23%, 3%, 27%, and 20% for each crop (wheat/soybeans/corn/ cotton) in sequence. For a given crop in a given year, response to topsoiling versus compost addition to the surface varied, and neither treatment appeared superior. Com and cotton yields on the mined land treatments were reduced despite the application of irrigation. Cotton quality was also adversely affected by the mining reclamation treatments. Results of these controlled experiments are somewhat encouraging. However, the implementation of our protocols will be complicated in practice if tailings and slimes cannot be re-blended to generate a reasonably uniform final reclaimed surface. Additional

Scots pine (Pinus sylvestris L.) ecosystem macronutrients budget on reclaimed mine sites—stand trees supply and stability

“…The following factors were determined in the soil samples: particle size distribution using areometrical method, pH potentiometrically in H 2 0 and in 1M KCl (1:2.5 ratio); organic carbon (C org ) and total sulphur (S t ) content using the infra-red absorption method, and total nitrogen (N t ) using the thermal conductivity method with the "Leco CNS 2000" analyser; basic exchangeable cations Na + , K + , Ca 2+ , Mg 2+ in 1 M NH 4 Ac by AAS detection; the content of total elements: Na, Mg, Ca, K after digestion in the mixture of HNO 3 , (d = 1.40) and 60% HClO 4 acid in 4:1 ratio using the AAS method. Phosphorus (P) in a form assimilated by plants was assayed using the Egner-Riehm method in calcium lactate extract ((CH 3 CHOHCOO) 2 Ca) acidified with hydrochloric acid to pH 3.6 and in total form using the molybdate blue colorimetry method from extracts in HClO 4 [35,36].…”

“…Nitrogen (and phosphorus) is one of the most deficient elements in reclaimed sites [5,54]. In the spoil heap soils of former lignite mines developing on tertiary carboniferous sands, geological carbon in the form of lignites often occurs and complicates soil C analysis.…”

“…Therefore, the C and N accumulation rate in the deeper horizons of the spoil heap soils, especially in case of TCS, may actually be overestimated. Although total N accumulation increases in the course of soil development in mine soils, both in those undergoing reclamation treatment and those where natural succession is taking place [5,12,14,38], it has been found that the average annual accumulation of N fluctuates and may change with the age of soil and vary by community type introduced in reclamation seedings [38].…”

“…As is true in many contemporary environmental problems, the rehabilitation of a drastically disturbed terrestrial system, such as lands mined for coal and minerals, requires site-specific knowledge to ensure the reclamation strategies chosen will be sustainable [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. In central Europe, a large proportion of post-mining landscapes are reclaimed to forest.…”

Transformation of Phosphorus and Nitrogen in Deep Row Biosolids Incorporation Technology in Coastal Plain Mining Sites in Virginia

“…The study is being conducted on a mine reclamation site in Dinwiddie County in Virginia with soil structure resulting from mineral sands processing in high clay deposits (Daniels et al, 1996). Seasonal water table on the site is within several feet of the soil surface.…”