A recent conversion of the grasslands to cropland degrading the soil quality (SQ), and impacting the soil erosion and crop productivity in the West Corn Belt (WCB) of the USA. The current study was conducted to estimate the spatial distribution of soil erosion at Big Sioux River (BSR) watershed scale using the Geographical Information System (GIS)-enabled Revised Universal Soil Loss Equation (RUSLE). Spatial data such as weather, a digital elevation model (DEM), land use maps and soils were used for assessment of soil erosion was downloaded from the easily available online sources. Data showed that about 7% of grassland acreage reduced from 2008 (24%) to 2015 (17%), whereas, about 7.4% of cropland acreage increased from 2008 (64.6%) to 2015 (72%) in the BSR watershed. This grassland conversion to cropland increased the soil erosion (estimated using the RUSLE model) from 12.2 T ha−1 year−1 in 2008 to 14.8 T ha−1 year−1 in 2015. The present study concludes that grassland conversion to cropland in the BSR watershed increased the soil erosion, therefore, management practices essential to be applied to reduce the erosion risk and various other ecosystem services.

Winter rye (Secale cereale L.) is an important cover crop (CC) in the northern Great Plains (NGP), yet concerns over its establishment under the variable weather conditions of this region are an important limitation for its widespread adoption. This study evaluated the impacts of no-till corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation with winter rye CC established in 2017 on (a) water quality (nitrate-N [NO 3 --N], ammonia-N [NH 4 + -N], and total nitrogen [TN]) and (b) soil healthparameters at the 0-to-15-cm depth. Data showed that rye CC biomass was 251 kg ha -1 in 2018, 1,213 kg ha -1 in 2019, and 147 kg ha -1 in 2020, coinciding with contrasting growing degree days for rye CC (i.e., 1,458, 2,042, and 794, respectively), as a consequence of variable weather conditions. Water quality was not affected for the periods when rye growth was <300 kg ha -1 . In the season when rye CC had greater biomass (1,213 kg ha -1 ), significant reductions in leached NO 3 --N (19-20%)and TN (8.5-16%) concentrations were observed due to greater N uptake by rye CC (18.8 kg N ha -1 ). Rye CC showed significantly (p ≤ .05) higher microbially active carbon ( ∼13%) and water-extractable organic N(∼11%) than the control treatment.Nonsignificant impacts on soil health indicators due to rye CC showed that the study duration (3 yr) may not be sufficient to see the beneficial impacts of CCs on soils.However, significant reductions in leached NO 3 --N and TN concentrations for one (2019) out of three study years suggest that rye with optimal growth has the potential of reducing N leaching and enhancing soil health for the NGP region.

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Reliable information on water use and availability at basin and field scales are important to ensure the optimized constructive uses of available water resources. This study was conducted with the specific objective to estimate Landsat‐based actual evapotranspiration (ETa) using the Operational Simplified Surface Energy Balance (SSEBop) model across the state of South Dakota (SD), USA for the 1986–2018 (33‐year) period. Validated ETa estimations (r2 = 0.91, PBIAS = −4%, and %RMSE = 11.8%) were further used to understand the crop water‐use characteristics and existing historic mono‐directional (increasing/decreasing) trends over the eastern (ESD) and western (WSD) regions of SD. The crop water‐use characteristics indicated that the annual cropland water uses across the ESD and WSD were more or less met by the precipitation amounts in the area. The ample water supply and distribution have led to high rainfed and low percentage of irrigated cropland (~2.5%) in the state. The WSD faced greater crop‐water use reductions than the ESD during drought periods. The landscape ETa responses across the state were found to be more sensitive than precipitation for the drought impact assessments. The Mann Kendall trend analysis revealed the absence of a significant trend (p > 0.05) in annual ETa at a regional scale due to the varying weather conditions in the state. However, about 12% and 9% cropland areas in the ESD and WSD, respectively, revealed a significant mono‐directional trend at pixel scale ETa. Most of the pixels under significant trend showed an increasing trend that can be explained by the shift in agricultural practices, increased irrigated cropland area, higher productions, moisture regime shifts, and decreased risk of farming in the dry areas. The decreasing trend pixels were clustered in mid‐eastern SD and could be the result of dynamic conversion of wetlands to croplands and decreased irrigation practices in the region. This study also demonstrates the tremendous potential and robustness of the SSEBop model, Landsat imagery, and remote sensing‐based ETa modelling approaches in estimating consistent spatially distributed evapotranspiration.

Impacts of integrated crop–livestock (ICL) systems on water quality have not been well studied. Water quality parameters were quantified for two 30‐min rainfall simulations in wheat (Triticum aestivum L.)–cover crop, cover crop, and rangeland grass control phases of a long‐term ICL study site in Mandan, ND, in 2017 and 2018. Both pre‐graze and post‐graze simulations were conducted. Nitrate‐N (NO3−–N), nitrite‐N (NO2−–N), ammonia‐N (NH4+–N), phosphate‐P (PO43−–P), and total suspended solid (TSS) concentrations and loads were evaluated in surface runoff water, along with concentrations of NO3−–N, NO2−–N, NH4+–N, and PO43−–P in infiltration water. Non‐parametric ranked two‐way analysis of variance was used to evaluate differences for vegetation type and grazing as fixed effects, with year as a random effect. Surface runoff concentrations of NO3−–N and NH4+–N were significantly different with cover crop and wheat phases being greater than grass. A grazing effect was also observed with pre‐graze significantly greater than post graze for NO2−–N, NH4+–N, PO43−–P, and TSS surface runoff concentrations. For infiltration water concentrations, similar significant effects of vegetation type were observed for NO3−–N and PO43−–P, while pre‐graze was also greater than post‐graze for NO2−–N and PO43−–P. Due to variable runoff volumes, no significant differences were observed for loads of any parameters. Minimal runoff volumes (0–6.7 L) and significant vegetation and grazing effects in nutrient infiltration water concentrations highlight the importance of infiltration in such studies, particularly at sites in the northern Great Plains.

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Land use land cover (LULC) and climate are the determinant factors for the soil water balance. The combined effect of LULC and climate change is of great importance for effective water resources planning and management. This study assessed the hydrological impact of long‐term implementation of integrated crop‐livestock (ICL) system with the projected climate scenarios on water yield using the Soil and Water Assessment Tool model over two time periods (i.e., near future [2021–2050] and far future [2070–2099]). This study was conducted in three phases over Skunk Creek watershed (SCW), South Dakota. In phase I, the impact of long‐term ICL system implementation (1976–2005; 30 years) on soil hydrology was evaluated. Phase II and phase III evaluated the impacts of projected climate changes under existing land cover and ICL system, respectively. Outcomes of phase I showed a significant decrease in water yield and surface runoff. Phase II showed the susceptibility of SCW to extreme events such as floods and waterlogging during spring, and droughts during summers under the projected climate changes. Phase III showed the reduction in water yield and surface runoff due to the ICL system and minimizing the induced detrimental impacts only due to climate change. This study provides a perspective on the possible impacts of the ICL system to mitigate the hydrological alteration due to climate change.

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