PM10 emission from feedlots in soils with different texture: Cattle trampling effect

DE ORO, LAURA A; BUSCHIAZZO, DANIEL E; PANEBIANCO, JUAN E; AVECILLA, FERNANDO

Simposio; Proceedings of the Blowing South: Southern Hemisphere Dust Symposium; 2021

Instituto Franco-Argentino sobre Estudios de Clima y sus Impactos - CONICET (INCITAP, CICTerra y CESIMAR) - UNLPam (Fac. CS. Exactas y Agronomía)

PM10 emission from feedlots in soils with different texture: Cattle trampling effectde Oro, L. A.1,3,*, Avecilla, F.1, Panebianco, J. E.1, Buschiazzo, D. E.11Institute for Earth and Environmental Sciences of La Pampa, National Council for Research andTechnology (INCITAP, CONICET-UNLPam), cc 186, 6300, Santa Rosa, Argentina.2Faculty of Natural Sciences, The National University of La Pampa (UNLPam), cc 300, 6300, Santa Rosa,Argentina.*Corresponding author: laurideoro@yahoo.com.arCattle feedlot surfaces can be an important aerosol source, but they have barely been studied. The action of the hooves on the loose, dry layer of soil and manure creates ideal conditions for particulate matter (PM) emissions. The feedlot system was considered as a set of surfaces that could potentially be affected by the processes of wind erosion and dust emission due to the direct effect of cattle trampling on the surface and the different activities related to commercial feedlot The objectives of this work were: a) to quantify the soil loss (Q) and the consequent emission of PM10 (FvPM10) from different surfaces within the feedlot: unpaved roads (UR), cropland (C) and cattle pen (CP); and b) to evaluate the cattle trampling effect in UR, C and CP on Q and FvPM10. Three cattle feedlots in a N-S transect were selected from the Pampas Semiarid Region (PSR) with different soil textures: Trenel (FT), Santa Rosa (FSR) and General Acha (FGA). On each surface (C, UR, CP), the effect of animal trampling was assessed at three levels of disturbance: a) no Disturbance (D0, soil samples without cattle trampling effect), b) low disturbance (DL, soil sample affected by low cattle trampling effect) and c) high disturbance (DH, soil sample affected by high cattle trampling effect). In a wind tunnel, erosion events were simulated at 10.5 m s-1 (µ*: 0.26 m s-1) during 5 min. A low animal trampling effect was simulated by 10 tramples of cow hoof and a high animal trampling effect was simulated by 60 tramples of cow hoof. The results showed that Q and FvPM10 were UR > C > CP and that the cattle trampling effect was generally directly proportional to Q and FvPM10 (p < 0.05). The highest Q and FvPM10 observed in the UR were due to a combination of high sand content, low organic matter, high EF and low aggregation that produces a highly erodible surface. The C surfaces, despite having a better aggregation, showed low dry aggregate stability and were moderately prone to wind erosion. On the contrary, CP are surfaces with a high proportion of organic material which enhances the formation of macro-aggregates (>6.4 mm) that are structurally stable and less prone to suffer wind erosion. Emissions from CP represented less than 5% of the total emissions from all the surfaces of each feedlot while in UR represented more than 60%. PM10 emission efficiency (calculated as FvPM10/Q) of the different surfaces(UR, CP and C) ranged between 10-6 and 10-4. In general the FvPM10/Q was higher in the feedlot with the finest soil texture (FT) than in the other two feedlots with coarser soil (FSR and FGA). Regarding the type of surface, emission efficiency from UR was lower than from C and CP surfaces. CP presented the lowest values of Q and FvPM10, but it showed high RE so it could be considered a continuous source of windderived emission of PM10 due to the effect of permanent trampling.