Replacement of fallow in crop–fallow systems with cover crops (CCs) may improve soil properties. We assessed whether replacing fallow in no‐till winter wheat ( Triticum aestivum L.)–fallow with winter and spring CCs for 5 yr reduced wind and water erosion, increased soil organic carbon (SOC), and improved soil physical properties on a Ulysses silt loam (fine‐silty, mixed, superactive, mesic Aridic Haplustolls) in the semiarid central Great Plains. Winter triticale (× Triticosecale Wittm.), winter lentil ( Lens culinaris Medik.), spring lentil, spring pea ( Pisum sativum L. ssp.), and spring triticale CCs were compared with wheat–fallow and continuous wheat under no‐till management. We also studied the effect of triticale haying on soil properties. Results indicate that spring triticale and spring lentil increased soil aggregate size distribution, while spring lentil reduced the wind erodible fraction by 1.6 times, indicating that CCs reduced the soil's susceptibility to wind erosion. Cover crops also increased wet aggregate stability and reduced runoff loss of sediment, total P, and NO 3 –N. After 5 yr, winter and spring triticale increased SOC pool by 2.8 Mg ha –1 and spring lentil increased SOC pool by 2.4 Mg ha –1 in the 0‐ to 7.5‐cm depth compared with fallow. Triticale haying compared with no haying for 5 yr did not affect soil properties. Nine months after termination, CCs had, however, no effects on soil properties, suggesting that CC benefits are short lived in this climate. Overall, CCs, grown in each fallow phase in no‐till, can reduce soil erosion and improve soil aggregation in this semiarid climate.
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 × 10−3 g·m−2·s−1 when 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.
The wind erosion process selectively removes smaller and lighter particles, leaving coarser and denser particles behind. These smaller and lighter particles typically represent the more fertile fraction of the soil which includes the organic component. In addition, changes in soil texture and organic matter can affect soil structure and water holding capacity. The limited research available indicates that surface soil textures become coarser and organic matter decreases over time under wind erosion. Limited data exists on the rate of selective removal by wind of soil components over time and subsequent effects on soil quality. The objective of this ongoing study is to determine the long term changes in soil particle size and organic matter resulting from wind erosion in western Kansas, an area historically susceptible to wind erosion. The surface soils of ten sites in western Kansas were sampled in 1948 by W.S. Chepil and analyzed for particle size and organic matter. Based on Chepil's location descriptions, these same sites were again sampled in 1984 (Lyles and Tatarko, 1986) and again in 1996, 2001, 2006, and 2011. All samples were taken within approximately 3 m (10 feet) of the original sampling points. Samples were analyzed for particle size distribution (texture) and organic matter content in the surface. Land managers were also surveyed to determine management history of each site and possible effects of land use on long term soil changes. For the 1948 samples, clay content was determined using a hydrometer, sand by sieving, and silt by difference. Organic matter was determined by the USDA NRCS National Soil Survey Laboratory, Lincoln, Nebraska, using the Walkley-Black titration method. Subsequent samples (post 1948) were analyzed for particle size by the pipette method, sand fraction by sieving, and silt content by difference. Post 1948 samples were also analyzed for organic matter at the Kansas State University Soil Testing Laboratory using the modified Walkley-Black method. Results show that changes in the measured properties are related to management on the ten study sites. The 1984 samples showed an average increase in sand content of 7.9% for nine of the sites sampled while silt content had an average decrease of 9.2% compared to the 1948 samples. An average decrease in organic matter of 0.6% for 8 of the sites studied was also observed. Since water erosion is not a problem on these nearly level sites and because the study area has historically experienced severe wind erosion during the Dust Bowl and after, the soil property changes were assumed to be primarily a result of selective removal by wind erosion. In addition, clean tillage was practiced by most of the land managers during the early period which leaves little protective vegetative material on the surface. Beginning in the late 1980s to the mid 1990s however, management histories show a transition to a greater emphasis on residue management including undercutting, mulch tillage, and one site planted to continuous grass under the CRP program. Following these changes in management, sand contents have stabilized while silt contents and organic matter contents generally increased. Wind erosion was likely causing an increase in sand and a decline in silt content and organic matter in these soils in the decades between 1948 and 1984, with potentially detrimental effects on soil structure, nutrient availability, and water-holding capacity. Subsequent adoption of conservation tillage and residue management has stabilized and in some cases reversed this trend in soil property changes.
Wind erosion is a major resource concern for rangeland managers because it can impact soil health, ecosystem structure and function, hydrologic processes, agricultural production, and air quality. Despite its significance, little is known about which landscapes are eroding, by how much, and when. The National Wind Erosion Research Network was established in 2014 to develop tools for monitoring and assessing wind erosion and dust emissions across the United States. The Network, currently consisting of 13 sites, creates opportunities to enhance existing rangeland soil, vegetation, and air quality monitoring programs. Decision-support tools developed by the Network will improve the prediction and management of wind erosion across rangeland ecosystems.
There is a need for greater understanding of the relationship of dust emission levels to disturbances of soil and vegetation indices that occur during military vehicle activities in Department of Defense training areas. A replicated field experiment was conducted in the fall of 2010 on two soils that dominate the military training grounds at Fort Riley, Kansas. Treatments consisted of two vehicle types, and three levels of vehicle passes. An Abrams M1A1 tank, representing tracked vehicles, and a Humvee representing wheeled military vehicles were used. Bulk density, above ground standing biomass, and plant cover were among the parameters measured before and after vehicular traffic. Samples were taken from curved, straight, and cross-over sections of the vehicle tracks. A mixed-model analysis of variance of the data indicates that the overall mean bulk density under the M1A1 were significantly higher than under the Humvee (p=0.05). In general, as the number of passes increased the bulk density under the M1A1 increased significantly (p=0.05), but the increases under the Humvee were not significant (p=0.05). Bulk densities were significantly larger in the curved part of the tracks than the straight part of the track. Large differences in biomass and vegetation cover between different treatments were observed. Comparison of spring and fall bulk density data showed significant difference at the 0-5 cm depth; indicating that the winter freeze and thaw cycles loosened the top soil layer.
Abstract. Off-road vehicle training can contribute to air quality degradation because of increased wind erosion as a result of soil disruption during high wind events; however, limited information exists regarding the impacts of off-road vehicle maneuvering on wind erosion potential of soils. This study was conducted to determine the effects of soil texture and intensity of training with off-road vehicles on fugitive dust emission potential due to wind erosion at military training installations. Multi-pass military vehicle trafficking experiments involving wheeled and tracked vehicles were conducted at three military training facilities with different vegetative conditions and soil textures (i.e., Fort Riley, KS; Fort Benning, GA; and Yakima Training Center, WA). The top 6 cm of soil was collected with minimum disturbance into trays and tested in a laboratory wind tunnel for dust emission potential. In wind tunnel testing, the amount of emitted dust was measured using a GRIMM aerosol spectrometer. The dust emission potential was significantly influenced by soil texture, vehicle type, and number of passes. For the light-wheeled vehicle, total dust emissions increased from 66 mg m-2 for undisturbed soil to 304 mg m-2 (357%) and 643 mg m-2 (868%) for 10 and 50 passes, respectively. For the tracked vehicle, an average increase in total dust emission of 569% was observed between undisturbed conditions and 1 pass, with no significant increase in emission potential beyond 1 pass. For the heavy-wheeled vehicle, emissions increased from 75 mg m-2 for undisturbed soil to 1,652 mg m-2 (1,369%) and 4,023 mg m-2 (5,276%) for 10 and 20 passes, respectively. Soil texture also played an important role in dust emission potential. For all treatment effects, there was a 1,369% difference in emissions between silty clay loam soil and loamy sand soil.
ABSTRACT: Ten soil sites in western Kansas sampled in 1948 were resampled in 1984 to compare the particle size distribution (texture) and organic matter content in the top 10 cm. Except at one site, the sand fraction increased; this increase ranged from 0.9 to 23.3 percentage points. The greatest changes occurred in the moderately coarse and coarse textured (sandy) soils. Overall changes in particle distribution were + 6.5, −7.2, and +0.7 percentage points for sand, silt, and clay, respectively, indicating that silt was removed through sorting by wind. Organic matter declined at 8 of the 10 sites, averaging about 19% overall or about 0.01 percentage points per year. Erosion or other factors are causing a slow decline in silt content and organic matter in these soils, with potentially detrimental effects on soil structure, nutrient availability, and water-holding capacity.
