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Lordsburg Playa, a dry lakebed in the Chihuahuan Desert of southwestern New Mexico (USA), is crossed by Interstate Highway 10 (I-10). Dust from the playa threatens highway safety and has caused dozens of fatal accidents. Two numerical models—the U.S. Department of Agriculture's Single-Event Wind Erosion Evaluation Program (SWEEP) and the American Meteorological Society and U.S. Environmental Protection Agency Regulatory Model (AERMOD)—were used to simulate and predict the generation and dispersion of windblown soil, dust, and PM10 from playa hotspots and estimate PM10 concentrations downwind. SWEEP simulates soil loss and particulate matter emissions from the playa surface, and AERMOD predicts the concentration of transported dust. The modeling was informed by field and laboratory data on Lordsburg Playa's properties, soil and land use/land cover databases, and weather data from meteorological stations. The integrated models predicted that dust plumes originating on the playa—including a large, highly emissive area away from the highway and a smaller, less emissive site directly upwind of the interstate—can lead to hourly average PM10 concentrations of tens, to hundreds of thousands, of micrograms per cubic meter. Modeling results were consistent with observations from webcam photos and visibility records from the meteorological sites. Lordsburg Playa sediment contains metals, as will its dust, but human exposures will be short-term and infrequent. This study was the first to successfully combine the SWEEP wind erosion model and the AERMOD air dispersion model to evaluate PM10 dispersion by wind erosion in a playa environment. With this information, land managers will be able to understand the potential levels of dust and PM10 exposure along the highway, and better manage human health and safety during conditions of blowing dust and sand at Lordsburg Playa. [ABSTRACT FROM AUTHOR]

In drylands around the world, ephemeral lakes (playas) are common. Dry, wind-erodible playa sediments are potent local and regional sources of dust and PM10 (airborne particles with diameters less than 10 μm). Dust clouds often cause sudden and/or prolonged loss of visibility to travelers on downwind roadways. Lordsburg Playa, in southwestern New Mexico, USA is bisected by Interstate Highway 10. Dust storms emanating from the playa have been responsible for numerous visibility-related road closures (including 39 road closures between 2012 and 2019) causing major economic losses, in addition to well over a hundred dust-related vehicle crashes causing at least 41 lost lives in the last 53 years. In order to improve understanding of the surfaces responsible for the dust emissions, we investigated the critical wind friction velocity thresholds and the dust emissivities of surfaces representing areas typical of Lordsburg Playa's stream deltas, shorelines, and ephemerally flooded lakebed using a Portable In-Situ Wind ERosion Laboratory (PI-SWERL). Mean threshold friction velocities for PM10 entrainment ranged from less than 0.30 m s− 1 for areas in the delta and shoreline to greater than 0.55 m s− 1 for ephemerally flooded areas of the lakebed. Similarly, we quantified mean PM10 vertical flux rates ranging from less than 500 μg m− 2 s− 1 for ephemerally flooded areas of lakebed to nearly 25,000 μg m− 2 s− 1 for disturbed delta surfaces. The unlimited PM10 supply of the relatively coarse sediments along the western shoreline is problematic and indicates that this may be the source area for longer-term visibility reducing dust events and should be a focus area for dust mitigation efforts. [ABSTRACT FROM AUTHOR]

Inducing biological soil crust (biocrust) development is an appealing approach for dust mitigation in drylands due to the resistance biocrusts can provide against erosion. Using a portable device, we evaluated dust emissions from surfaces either inoculated with biocrust, amended with a plant‐based soil stabilizer, or both at varying wind friction velocities. Four months after application, emissions from all treatments were either indistinguishable from or greater than controls, despite evidence of biocrust establishment. All treatments had greater surface roughness and showed more evidence of entrapment of windblown sediment than controls, factors which may have been partially responsible for elevated emissions. There was a synergistic effect of inoculation and stabilizer addition, resulting in a nearly two‐fold reduction in estimated emissions compared to either treatment alone. Stepwise regression analysis indicated that variables associated with surface crust strength (aggregate stability, penetration resistance) were negatively associated with emissions and variables associated with sediment supply (sand content, loose sediment cover) were positively associated with emissions. With more time to develop, the soil‐trapping activity and surface integrity of biocrust inoculum and soil stabilizer mixtures is expected to increase with the accumulation of surface biomass and enhancement of roughness through freeze–thaw cycles. © 2019 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Phenology is critical in simulating crop production and hydrology and must be sufficiently robust to respond to varying environments, soils, and management practices. Phenological algorithms typically focus on the air temperature response function and rarely quantify the phenological responses to varying water deficits, particularly for versions of the Environmental Policy Integrated Climate model (EPIC)-based plant growth component used in many agroecosystem models. Three EPICbased plant growth components (Soil Water Assessment Tool [SWAT], Wind Erosion Prediction System [WEPS], and the Unified Plant Growth Model [UPGM]) have been incorporated into the spatially distributed Agricultural Ecosystems Services model [AgES], and only the UPGM includes a phenological response to varying water deficits. These three plant components were used to evaluate the phenological responses of winter wheat (Triticum aestivum L.) to varying water deficits and whether having a water stress factor in UPGM improves the simulation of phenology. A 3-yr irrigation study and a 4-yr study across a rainfed landscape were used in the evaluation. Only the UPGM simulated all five of the developmental stagesmeasured. The UPGM was the only component that simulated a phenological response to variable water deficits, resulting in better prediction of phenology. For example, the RMSE (days) and relative error (RE, days) decreased and index of agreement (d) increased in predicting maturity from SWAT (RMSE = 18.4; RE = 9.2; d = 0.34) to WEPS (RMSE = 6.2; RE = 1.0, d = 0.63) to the UPGM (RMSE = 6.1; RE = 0.1; d = 0.70). Incorporating phenological responses to varying water deficits improves the accuracy and robustness of predicting phenology, which is particularly important in spatially distributed agroecosystem models. [ABSTRACT FROM AUTHOR]

Purpose: Extensive vegetation recovery has been implemented to control severe soil erosion on the Loess Plateau, China. However, no systematic study has been done on the soil improvement benefit and preferable pattern of vegetation rehabilitation. In this study, the effects of vegetation restoration on soil physical properties at ten sites with different vegetation types and varying restoration periods were investigated.Materials and methods: The experiment was carried out in the Yanhe river basin in the hilly-gully region of the Loess Plateau. Ten sites, including two replanted arboreal forests for 25 and 35 years, three replanted scrubland for 15, 30, and 45 years, four secondary natural grassland for 10, 20, 30, and 40 years, and one farmland, were selected for soil sampling. Sampling was conducted at 0-20 cm and 20-40 cm layers.Results and discussion: Vegetation restoration significantly decreased bulk density, and increased aggregate stability and saturated hydraulic conductivity (Ks), while their effects on porosity was complicated. The soil texture class did not change with vegetation succession, but minor differences in sand, silt, and clay components were observed. Bulk density, macroporosity, and > 0.25 mm aggregate stability were the principal physical parameters that affected Ks. Moreover, bulk density had the most effect on Ks (− 0.84), while > 0.25 mm aggregate stability had the lowest impact (0.38). Bulk density and Ks were correlated with most of the other soil physical properties. Replanted scrubland and secondary natural grassland had higher soil physical quality index (SDexter) than replanted arboreal forests and farmland.Conclusions: It is reasonable to take bulk density and Ks as the indicators to evaluate the effect of vegetation restoration on soil physical properties. Planting shrubs and grassland is better than forest for eco-environment rehabilitation in the study area. Results of this study provide a reference to regional eco-environmental rehabilitation and conservation. [ABSTRACT FROM AUTHOR]

Dust emissions from unpaved roads are one of the main pollutants affecting air quality around the world. As part of initial air quality studies in Tuxtla Gutiérrez (TGZ), Chiapas, Mexico, urban aeolian emission events from unpaved roads and simple meteorological inputs were measured in February 2014 at two different sites located within the city to characterize emissions for representative road conditions and to produce Industrial Source Complex (ISC3) model inputs. Emissions of particulate matter of aerodynamic diameter less than 10 µm (PM10) were determined for eight wind erosion events. PM10 concentrations were measured downwind from sites using a Minivol sampler during February and March 2014. Three high PM10 concentration scenarios, associated with unstable conditions generated by cold fronts (CF) were selected to simulate dust plume dispersion to identify impacted areas. Results show that unpaved roads represent a potential source of dust that affect air quality of urban regions; in this study generating emissions ≥ 1.92 x 10-3 g·m-2·s-1when winds ≥ 6 m·s-1 were present. Air pollution events that exceed the Mexico national standard for 24-h average PM10 concentration (≥75 µg·m-3) were observed, impacting different areas in the city, representing a risk to human health. This demonstrates the influence of CF over southern Mexico, generating high PM10 concentrations in urban regions. [ABSTRACT FROM AUTHOR]

Abstract: Crop residue removal can affect the susceptibility to soil wind erosion in climates such as those of the Central Great Plains, United States. Six on‐farm trials were conducted in Kansas from 2011 to 2013 to determine the effects of winter wheat (Triticum aestivum L.), corn (Zea mays L.), and grain sorghum (Sorghum bicolor (L.) Moench), residue removal at 0, 25, 50, 75, and 100% of initial height on soil wind erosion parameters. Those parameters include soil surface random roughness (RR), and wind erodible fraction (EF; aggregates <0.84 mm), geometric mean diameter (GMD) and geometric standard deviation (GSD), stability of dry aggregates (DAS). Complete (100%) residue removal decreased the surface RR, increased EF, and decreased GMD. Overwinter EF values increased for five of six sites from fall 2011 to spring of 2012, particularly for the uppermost removal height (≥75%). Measured EF, GMD, GSD, DAS, and RR were also input into the Single‐event Wind Erosion Evaluation Program (SWEEP) to determine the effect of these parameters on simulated soil loss. The SWEEP simulated the wind velocity needed to initiate wind erosion as well as soil loss under each residue removal height at a wind velocity of 13 m s−1 for three hours. Threshold wind velocity required to initiate wind erosion generally decreased with increasing crop residue removal height, particularly for >75% removal. Total estimated soil loss over the three‐hour event ranged from ≈2 to 25 Mg ha−1, depending on EF, GMD, GSD, RR, and percent crop residue cover. Removing 75% residue increased simulated wind erosion at three of six sites while removing 50% appears sustainable at all six study sites. Findings reinforce the need for site‐by‐site consideration of the potential amount of crop residue that may be harvested while mitigating wind erosion. Study results indicate the value of maintaining residue at >75% of original height. [ABSTRACT FROM AUTHOR]

Implications of corn (Zea mays L.) residue grazing and baling on wind erosion in integrated crop--livestock systems are not well understood. This study (i) determined soil properties affecting wind erosion potential including dry aggregate-size distribution, geometric mean diameter (GMD), geometric standard deviation of dry aggregates, and wind-erodible fraction (WEF), (ii) correlated these properties with soil organic C (SOC) and particulate organic matter (POM) and (iii) simulated soil loss using the Single-event Wind Erosion Evaluation Program (SWEEP) model after 7 and 8 yr of irrigated no-till corn residue management in a semiarid region in west-central Nebraska. Residue treatments were: control (no residue removal), light grazing (2.5 animal unit months [AUM] ha-1), heavy grazing (5.0 AUM ha-1) and baling. We simulated soil loss for a 3-h windstorm with a wind velocity of 13 m s-1. Soil properties differed in spring but not in fall. Baling reduced 6.3- to 45-mm macroaggregates by 37% and GMD by 80% and increased WEF by 25% relative to the control. Light and heavy grazing, after 8 yr, significantly reduced 6.3- to 14-mm macroaggregates 43% compared with the control and tended to reduce GMD and increase WEF, although not statistically significant. As residue cover decreased, GMD decreased and WEF increased. Residue removal did not reduce SOC and POM concentrations, but soil erodibility decreased as POM increased. Simulation showed that soil erodibility increased as residue cover decreased in spring and baling increased the wind erosion potential. Overall, residue baling increases the wind erosion potential but residue grazing has smaller effects in this semiarid environment. [ABSTRACT FROM AUTHOR]

Addition of cover crops and animal manure following corn {Zea mays L.) stover removal for expanded uses may mitigate negative soil property effects of stover removal. We studied the short-term (3 yr) cumulative impacts of stover removal with and without winter rye (Secale cereale L.) cover crop or animal manure application on near-surface (0- to 5-cm depth) soil properties under irrigated no-till continuous corn on a Hastings silt loam (fine, smectitic, mesic Udic Argiustolls) (<3% slope) near Clay Center, NE. Treatments were irrigation levels (full and deficit), amelioration practices (none, cover crop, or animal manure), stover removal (no removal or maximum removal), and N fertilization (125 or 200 kg N ha-1). Data collected after 3 yr indicate that stover removal (63%) reduced geometric mean diameter of dry aggregates 93%, increased erodible fraction sixfold, and reduced aggregate stability 32% compared with plots without stover removal. Stover removal from plots with cover crop or manure reduced dry aggregate size and stability and increased erodible fraction compared with plots without removal and amelioration practices, indicating that amelioration practices did not offset stover removal effects. Stover removal reduced wet aggregate stability and soil organic C (SOC) concentration in the 0- to 2.5-cm depth, but cover crop or manure mitigated these small reductions. Stover removal did not change water infiltration rates and had small effects on particulate organic matter (POM). Overall, in the short term, cover crop or manure may not provide sufficient protection from raindrop impact and wetting and drying cycles to maintain soil structure, resulting in increased susceptibility to wind erosion. Use of these amelioration practices, however, may offset changes in surface layer wet aggregate stability and SOC after high rates of stover removal in this region. [ABSTRACT FROM AUTHOR]

Dedicated bioenergy crops such as perennial warm-season grasses (WSGs) may reduce soil erosion and improve soil properties while providing biomass feedstock for biofuel. We quantified impacts of perennial WSGs and row crops on soil wind erodibility parameters (erodible fraction, geometric mean diameter of dry aggregates, and aggregate stability) and soil organic carbon (SOC) concentration under a dedicated bioenergy crop experiment in eastern Kansas after 4 and 5 yr of management. Soil properties were measured under switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii L.), miscanthus (Miscanthus x giganteus), and annual row crops including continuous corn (Zea mays L.), photoperiod sorghum [Sorghum bicolor (L.) Moench.], sweet sorghum, and grain sorghum. Perennial WSGs reduced wind erodible fraction by 1.08 to 1.16 times compared with row crops. The geometric mean diameter of dry aggregates under switchgrass and miscanthus was 2.8 to 4.5 times greater than under row crops. Dry soil aggregate stability under miscanthus and big bluestem was greater than under row crops. After 5 yr, differences in SOC concentration between WSGs and row crops were not statistically significant for the 0- to 15-cm depth. Photoperiod sensitive and sweet sorghum had greater biomass yield than WSGs. In 2011, miscanthus yielded more biomass than corn by 5.3 Mg ha-1. Overall, growing dedicated bioenergy crops can reduce the soil's susceptibility to wind erosion but may not significantly increase SOC concentration in this region in the short term. [ABSTRACT FROM AUTHOR]