Coal surface mining in the northern Great Plains of the United States often produces mining spoils with physical and chemical barriers to successful revegetation, and this has resulted in experiments on reclamation with salvaged soil materials. There is a need to determine changes in soil properties and plant community and productivity decades after reclamation. Experiments were initiated in the mid-1970s by placing wedge-shaped masses of Haplustoll soils over leveled, saline-sodic mine spoils forming 2−5% hillslopes approximately 50 m long at two sites near Zap and Stanton, North Dakota. Seeding treatments at Zap included alfalfa (Medicago sativa L.), crested wheatgrass (CWG, Agropyron cristatum [L.] Gaertn.), smooth bromegrass (SBG, Bromus inermis Leyss.), and Russian wildrye (Psathyrostachy juncea [Fisch.] Nevski); at Stanton, native grasses (two Bouteloua spp.) replaced P. juncea. We examined soil, plant community, and productivity changes 3 decades after the start of the experiments. Leaching of soluble salts in subsoils and mine spoils improved soil quality (SQ). SQ improved more in lower slope areas because more rootzone was occupied by low SQ mine spoil. Initial forage yield patterns showed dependency on hillslope position, reflecting both soil depth effects in lower slope parts of hillslopes and apparent water redistribution effects in middle and upper slope areas. Evidence of SQ improvement over time was inferred by substantial decreases in yield dependency on hillslope position at both sites. The Zap site was grazed more heavily than Stanton, and species composition at Zap was 46% cool-season grasses (CWG greatest) and 40% broadleaves. Stanton had 87% cool-season grasses (SBG greatest) with 3% broadleaves. Leaching of salts was threefold greater at Zap and may have resulted from an abundance of deep-rooted broadleaves. Reclaiming mined land with salvaged soil and revegetation can improve SQ of mine spoil, which our results infer was driven by root growth and establishment of macroporosity.

美国大平原北部的煤层开采通常会产生具有物理和化学屏障的矿渣，从而无法成功进行植被恢复，这导致了利用被打捞的土壤材料进行填海的实验。开垦后几十年，有必要确定土壤性质，植物群落和生产力的变化。实验始于1970年代中期，在北达科他州Zap和Stanton附近的两个地点，将楔形的Haplustoll土块铺在水平的盐碱矿渣上，形成2％至5％的山坡，长约50 m。Zap的播种处理包括苜蓿（Medicago sativa L.），有冠小麦草（CWG，Agropyron cristatum [L.] Gaertn。），光滑的无芒雀麦（SBG，Bermus inermis Leyss。）。，和俄罗斯野黑麦（Psathyrostachy juncea [Fisch。] Nevski）；在斯坦顿，当地草（两个Bouteloua物种）取代了P. juncea。实验开始后3年，我们检查了土壤，植物群落和生产力变化。地下土壤和矿渣中可溶性盐的浸出改善了土壤质量（SQ）。低坡度地区的SQ改善更多，因为低SQ矿渣占据了更多的根带。最初的牧草产量模式显示出对山坡位置的依赖性，反映了山坡下坡部分的土壤深度效应和中上坡地区的表观水分再分配效应。随着时间的推移，SQ改善的证据是由于两个站点上对山坡位置的产量依赖性显着降低所致。Zap站点的放牧量比Stanton重，并且Zap的物种组成是46％的淡季草（CWG最大）和40％的阔叶草。斯坦顿拥有87％的淡季草（SBG最大）和3％的阔叶草。Zap的盐分浸出量增加了三倍，这可能是由于根深蒂固的阔叶树丰富而引起的。用打捞过的土壤和植被恢复开垦的土地可以改善矿渣的SQ，我们的结果推断这是由根部生长和大孔隙的建立驱动的。