In the early 1970’s, it was determined that the most feasible way to reclaim lands disturbed by coal surface mining in the Northern Great Plains region was through the respreading of salvaged soil. In 1974, scientists at the Northern Great Plains Research Laboratory of the Agricultural Research Service -- U. S. Department of Agriculture (USDA-ARS) initiated two experiments designed to determine the thicknesses of respread soil necessary to restore productivity to difficult-to-reclaim sodic minespoils in central North Dakota (ND). In both experiments, motorscraper and other earthmoving equipment was used to construct wedge-shaped masses of subsoil materials over leveled minespoils and then to cover these with uniform thicknesses of topsoil material. Topsoil consisted of predominately A horizon material from Haplustoll soils, and subsoil consisted of B and C horizon material. In one experiment near the town of Stanton ND, a subsoil wedge was constructed on leveled minespoil and consisted of 12 long contiguous blocks of material (which were the main plots), three replications of four topsoil thickness treatments. For each replication, three of the main treatment blocks consisted of subsoil material, and one was a 3:1 subsoil – topsoil mix. The topsoil treatments consisted of no topsoil, 20 cm, 60 cm, and no topsoil on the mixed soil block. Each main treatment block was split into four long strips and seeded to crops of alfalfa, crested wheatgrass, spring wheat, and warm-season grass mix. The wedge was 240 m long, 65 m wide, and 2.1 m high at the summit. In another experiment near the town of Zap ND, a double subsoil wedge was constructed on leveled minespoil and consisted of six long contiguous blocks of material (which were the main plots), two replications on each side of the wedge, for a total of four replications with three subsoil quality treatments. The subsoils varied in soil texture, salinity and sodicity. The wedge was covered with a uniform 20 cm thickness of topsoil. Each main treatment block was split into four long strips and seeded to the same crops as the Stanton site with the exception of warm-season grass mix, which was replaced with Russian wildrye. The double wedge was 124 m long, and about 50 m from each toe to summit for a total width of 102 m and was 2.1 m high at the summit. Resources in this dataset:

Resource Title: Experimental Details File Name: Experimental Details.docx Resource Description: Background information for Stanton and Zap experimental sites, including figures of constructed wedges.

Resource Title: Wedge Data Dictionary File Name: Wedge Data Dictionary.xlsx Resource Description: Data dictionary for soil data collected from minespoil experiments near Stanton and Zap, North Dakota, 1976-1981.

Resource Title: Stanton site ionic soil solution data File Name: Stanton site ionic soil solution data.csv Resource Description: Data for soil pH, electrical conductivity, exchangeable Ca, Mg, and Na, sodium adsorption ratio, and saturation percentage.

Resource Title: Stanton site soil C, N and P data File Name: Stanton site soil C, N and P data.csv Resource Description: Data for soil organic C, total N, ammonium-N, nitrate-N, and extractable P.

Resource Title: Stanton site soil physical data File Name: Stanton site soil physical data.csv Resource Description: Data for soil water content at 0.33 and 15 bar.

Resource Title: Zap site ionic soil solution data File Name: Zap site ionic soil solution data.csv Resource Description: Data for soil pH, electrical conductivity, exchangeable Ca, Mg, and Na, sodium adsorption ratio, and saturation percentage.

Resource Title: Zap site soil C, N and P data File Name: Zap site C, N and P data.csv Resource Description: Data for soil organic C, total N, ammonium-N, nitrate-N, and extractable P.

Resource Title: Zap site soil physical data File Name: Zap site soil physical data.csv Resource Description: Data for soil water content at 0.33 and 15 bar, sand, silt, and clay content, and textural class.

Resource Title: Aggregated ionic soil solution data File Name: Wedge curation aggregated ionic soil solution data.xlsx Resource Description: Data shared in separate tabs organized by year, ___location, and metric.

Resource Title: Aggregated soil C, N and P data File Name: Wedge curation aggregated C, N and P data.xlsx Resource Description: Data shared in separate tabs organized by year, ___location, and metric.

Resource Title: Aggregated soil physical data File Name: Wedge curation aggregated soil physical data.xlsx Resource Description: Data shared in separate tabs organized by year, ___location, and metric.