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Johnson et al., 2016). Removal of crop residue reduces soil organic carbon (SOC), and impacts soil productivity. However, the impacts of residue removal rates on soils depend on certain factors such as soil texture, soil topography, initial contents of SOC, tillage, and cropping system (Blanco-Canqui et al., 2013). Water is the most limiting factor for crop production in regions where either irrigation is not available or precipitation is limited (Das et al., 2017). Water stored in the soil profile helps to fulfill the water requirement for following crop in the rotation. Corn residue left behind after corn harvest helps to conserve water in soil (Iqbal et al., 2013) and plays an important role in water conservation and hence increase grain yields where irrigation or precipitation is a limiting factor in crop production (Van Donk et al., 2010; VanLoocke et al., 2012). The long-term adoption of CC could negate the adverse effects of residue removal and increase SOC and improve soil water dynamics, eventually improving crop production and soil productivity (Basche et al., 2016a; Basche et al., 2016b; Kahimba et al., 2008). A study by Chahal and Van Eerd (2018) showed that cover crop increased SOC concentrations by 8.4 to 9.3% and crop yield by 7.9 to 22% compared with no cover crop treatment. Basche and DeLonge (2017) showed that adoption of CC for more than 10 yr improved soil hydrological properties

Changes in land use and alteration of the ecosystem can significantly affect soil physical, chemical, and biological properties. In this study, changes in soil organic carbon (SOC), root biomass, bulk density (ρb), water stable aggregates (WSA), and infiltration rates were examined in reconstructed prairies varying in age and landscape position. The objective of the study was to determine the potential of landscape position effect on these selected soil properties in reconstructed prairies. Findings show that SOC increased as years since prairie establishment increased and had a positive correlation with infiltration rate and WSA. The opposite was true for ρb, where it decreased as prairie age increased and negatively correlated with SOC. However, the effects of SOC and ρb on infiltration rates varied by landscape slope position and age of prairie establishment. Root biomass, SOC, and WSA had decreased, while ρb increased at the midslope compared to the summit and toe-slope positions resulting in lower infiltration rates. Although the summit and the toe-slope positions had similar soil properties, infiltration rates were much greater in the toe-slope position. This was ascribed to the toe-slope position's superior WSA, due to greater SOC concentrations. In general, this study shows that over time, increases in SOC did promote aggregate formation and lower ρb, creating more permeable soil surfaces in these reconstructed prairies. However, better soil conservation practices that reduce soil surface water runoff in the midslope in particular are needed during the first few years of prairie establishment.

In addition to their aesthetic and environmental qualities, reconstructed prairies can act as C sinks and potentially offset rising atmospheric CO(2) concentration. The objective of this study was to quantify C budget components of newly established prairies on previously cultivated land. Net ecosystem production (NEP) was estimated using a C budgeting approach that assessed SOC content, soil surface CO(2)-C emission, and above- and belowground plant biomass. Study was conducted in southern Iowa, in 2005 to 2007. Results show that differences between sites for potential total C input were primarily due to root biomass contributions, which ranged from 0.8 to 5.4 Mg C ha(-1). Average potential aboveground biomass C input was 2.7 Mg C ha(-1) in 2006 and 5.5 Mg C ha(-1) in 2007. Total soil CO(2)-C emissions from heterotrophic respiration increased as prairie age increased from 2.9 to 4.0 Mg C ha(-1) and 3.1 to 4.7 Mg C ha(-1) in 2006 and 2007, respectively. Determination of NEP showed that the 1998 and 2003 reconstructed prairie sites had the greatest potential for soil C sequestration at 4.1 and 4.4 Mg C ha(-1). Increases in SOC content were only observed in the youngest established prairie site (2003) and the no-till site in 2003 at 2.1 and 2.6 Mg C ha(-1) yr(-1), respectively. Declines of SOC sequestration rates occurred when potential C equilibrium was reached (R(h) = NPP) within 10 yr since prairie establishment.

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A life cycle assessment with carbon (C) as the reference unit was used to balance the benefits of land preparation practices of establishing tall-grass prairies as a crop for reclaimed mine land with reduced environmental damage. Land preparation and management practices included disking with sub-soiling (DK-S), disking only (DK), no tillage (NT), and no tillage with grazing (NT-G). To evaluate the C balance and energy use of each of the land preparations, an index of sustainability (I s = C O /C I , Where: C O is the sum of all outputs and C I is the sum of all inputs) was used to assess temporal changes in C.Of the four land preparation and management practices, DK had the highest I s at 8·53. This was due to it having the least degradation of soil organic carbon (SOC) during land-use change (À730 kg ha À1 y À1 ) and second highest aboveground biomass production (9,881 kg ha À1 ). The highest aboveground biomass production occurred with NT (11,130 kg ha À1 ), although SOC losses were similar to DK-S, which on average was 2,899 kg ha À1 y À1 . The I s values for NT and DK-S were 2·50 and 1·44, respectively. Grazing from bison reduced the aboveground biomass to 8,971 kg ha À1 compared with NT with no grazing, although stocking density was low enough that I s was still 1·94. This study has shown that converting from cool-season forage grasses to tall-grass prairie results in a significant net sink for atmospheric CO 2 3 years after establishment in reclaimed mine land, because of high biomass yields compensating for SOC losses from land-use change.

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