%0 Journal Article %J Aeolian Research %D 2020 %T Comparison of soil-aggregate crushing-energy meters %A Pi, H. %A Huggins, D.R. %A Webb, N.P. %A Sharratt, B. %K Abrasion %K Binding energy %K Dry aggregate stability %K Dust emission %K Particle cohesion %K Wind erosion %X

Dry aggregate stability (DAS) is an important factor influencing soil wind erosion, dust emission and crop production. Historically and to the present, DAS has been determined using a horizontal- or vertical-plate crushing meter (Soil-Aggregate Crushing-Energy Meter, hereafter SACEM). The intent of this paper was to compare the performance of horizontal-plate SACEM with a commercial penetrometer (Mohr Digi-Test, hereafter MDT). The performance of both instruments was tested on aggregates collected from various soil types, crop rotations, soil amendments, and tillage systems across the inland Pacific Northwest United States (iPNW). Results indicated no consistently significant difference in DAS measured by the MDT and SACEM. However, there was evidence that SACEM under-estimated or MDT over-estimated DAS by 74 to 368% in measuring the stability of strong aggregates (DAS > 3 J kg−1). Both instruments measured higher DAS for no-tillage summer fallow, winter wheat-summer fallow (WW-SF) rotations, and no green manure treatments compared with other tillage practices, oilseed rotations, and green manure treatments. The SACEM that has historically been used in measuring soil DAS can be replaced by the commercial penetrometer (MDT). Nonetheless, differences in the performance of instruments in measuring the stability of strong aggregates poses risks.

%B Aeolian Research %V 42 %G eng %& 100559 %R doi:10.1016/j.aeolia.2019.100559 %0 Journal Article %J CATENA %D 2020 %T Critical standing crop residue amounts for wind erosion control in the inland Pacific Northwest, USA %A Pi, H. %A Webb, N.P. %A Huggins, D.R. %A Sharratt, B. %K Chickpea %K Frontal area index %K Spring canola %K Wind erosion model %K Winter wheat %X

Crop residue is an important factor influencing wind erosion of cultivated soils. Establishing soil surface protection afforded by standing crop residue is critical for land managers seeking to reduce or prevent soil loss by wind erosion and the impacts of blowing dust from agricultural lands. The objectives of this study were to evaluate the effect of standing residue on soil wind erosion in the inland Pacific Northwest (iPNW), USA, and test the performance of the plant factor algorithm of the Agricultural Policy/Environmental eXtender (APEX) and Revised Wind Erosion Equation (RWEQ) models in influencing soil loss. The effect of standing winter wheat (Triticum aestivum L.), spring canola (Brassica napus L.), and chickpea (Cicer arietinum) residue on wind erosion, remaining from major commodity crops in the region, was tested in a laboratory wind tunnel using four levels of residue density. The impact of standing residue in controlling wind erosion was compared and analyzed in terms of residue density and their respective frontal area index. Our results show that residue at a density characteristic of the production environment (110 standing residue elements m−1 for winter wheat, 20 standing elements m−1 for canola, and 16 standing elements m−1 for chickpea) provided significant protection to the soil surface from wind erosion. Soil loss at this level of residue density was reduced by 73.3, 53.4, and 60.9% for respectively winter wheat, spring canola, and chickpea (frontal area indexes are 0.172, 0.104, and 0.026 respectively) compared with a surface without residue. The soil surface was found to be at significant risk from wind erosion when residue densities of the three crop types were <50% of the typical production amounts. Although not consistently significant, soil loss decreased as wind direction shifted from parallel to perpendicular with the standing residue row. The APEX model adequately simulated winter wheat and spring canola residue protection but had low accuracy in representing chickpea residue effects relative to the wind tunnel experiments. In contrast, the RWEQ model appeared inadequate in simulating soil loss for the winter wheat and canola treatments but adequately represented chickpea residue effects. Differences in model accuracy for different crop types must be considered by producers and managers to determine whether model information used to select practices to control wind erosion are likely to result in under- or over-protection of soil resources.

%B CATENA %V 195 %G eng %& 104742 %R doi:10.1016/j.catena.2020.104742 %0 Journal Article %J Journal of Soil and Water Conservation %D 2019 %T Climate change impacts on wind and water erosion on US rangelands %A Edwards, B.L. %A Webb, N.P. %A Brown, D.P. %A Elias, E. %A Peck, D.E. %A Pierson, F.B. %A Williams, C.J. %A Herrick, J.E. %K climate change %K rangeland %K soil erosion %K water erosion %K Wind erosion %X

Soil erosion by water and wind in US rangelands has serious implications for rangeland health and food security and poses significant hazards to human health and communities. Accordingly, understanding how future climate change may impact soil erosion is critical for developing appropriate management strategies that mitigate negative impacts to the extent practical and potentially build resilience. Here, we review potential impacts of climate change on controls of erosion in US rangelands and discuss potential erosion responses. Projected climate changes are expected to have regionally variable effects on important controls of erosion, especially vegetation cover; community composition; frequency, magnitude, and geographical range of fire disturbance; and high intensity, erosive weather events, all of which have the potential to increase rangeland vulnerability to erosion. We identify knowledge gaps relevant to these controls and discuss management considerations to address climate change impacts to soil erosion concerns for US rangelands. In order to improve resilience and the efficacy of climate change adaptation, we recommend that existing monitoring data be used to create assessments of vulnerability, that soil erosion should be explicitly included in management benchmarks and decision support tools, and that no-regrets management options be implemented in anticipation of future impacts.

%B Journal of Soil and Water Conservation %V 74 %8 07/2019 %G eng %& 405 %R 10.2489/jswc.74.4.405