|SCHILLINGER, WILLIAM - Washington State University
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2018
Publication Date: 12/6/2018
Citation: Sharratt, B.S., Kennedy, A.C., Hansen, J.C., Schillinger, W. 2018. Soil carbon loss by wind erosion of summer-fallow fields in Washington’s dryland wheat region. Soil Science Society of America Journal. 92(6):1551-1558. https://doi.org/10.2136/sssaj2018.06.0214.
Interpretive Summary: Carbon is the basis of a healthy soil and essential to the sustainability of agricultural production. Loss of soil carbon, however, can occur by microbial degradation, leaching, and runoff. Comparatively little is known about carbon loss associated with wind erosion, which is a major concern in the Inland Pacific Northwest. Sediment eroded by wind contained about 0.9% carbon. Carbon loss during single wind erosion events was as high as 18.5 kg C ha-1 or about 1.8% of the carbon contained in the topsoil. Dryland wheat growers must be judicious in managing their crop land to minimize wind erosion and thereby conserve both the soil and carbon resource.
Technical Abstract: Wind erosion of cropland negatively affects soil quality and productivity in the winter wheat (Triticum aestivum L.) - summer fallow (WW-SF) region of the inland Pacific Northwest (PNW) USA. Loss of soil diminishes the finite resource base and the concurrent loss of soil organic carbon (SOC) affects inherent physical, chemical, and biological properties of the soil. The objective of this study was to quantify SOC loss from windblown summer-fallow soils. Creep and Big Spring Number Eight (BSNE) samplers, positioned at fixed heights from 0 to 1.5 m above the soil, were used to trap eroding soil during major wind events over an 8-y period. Carbon (C) content of sediment trapped by these samplers ranged from 6 to 11.6 g C kg sediment-1. Enrichment ratios (ER) for C ranged from 0.8 to 4.9, indicating the trapped sediment was generally enriched in C as compared with the parent soil. Averaged across all sites and wind events, the amount of soil eroded from fields ranged from 0.4 to 18.5 kg ha-1 and contained 3.2% more C than the parent soil. The ongoing decline in SOC since the advent of dryland farming in the region 140 y ago is most commonly attributed to degradation by microbes and oxidation. However, our data, combined with historic accounts of wind erosion in the WW-SF region, strongly suggest that loss of SOC may also be due to wind erosion. Farmers in the WW-SF region are encouraged to further adopt conservation tillage practices to retain residue and soil aggregates on the surface and thereby reduce the degradation of agricultural soils by wind erosion.