Effect of Sieving on Ex Situ Soil Respiration of Soils from Three Land Use Types
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Effect of Sieving on Ex Situ Soil Respiration of Soils from Three Land Use Types Adetunji Alex Adekanmbi 1 & Liz J. Shaw 1 & Tom Sizmur 1 Received: 23 August 2019 / Accepted: 7 January 2020 # The Author(s) 2020
Abstract This study aims to investigate the effect of sieving on ex situ soil respiration (CO2 flux) measurements from different land use types. We collected soils (0–10 cm) from arable, grassland and woodland sites, allocated them to either sieved (4-mm mesh, freshly sieved) or intact core treatments and incubated them in gas-tight jars for 40 days at 10 °C. Headspace gas was collected on days 1, 3, 17, 24, 31 and 38 and CO2 analysed. Our results showed that sieving (4 mm) did not significantly influence soil respiration measurements, probably because micro aggregates (< 0.25 mm) remain intact after sieving. However, soils collected from grassland soil released more CO2 compared with those collected from woodland and arable soils, irrespective of sieving treatments. The higher CO2 from grassland soil compared with woodland and arable soils was attributed to the differences in the water holding capacity and the quantity and stoichiometry of the organic matter between the three soils. We conclude that soils sieved prior to ex situ respiration experiments provide realistic respiration measurements. This finding lends support to soil scientists planning a sampling strategy that better represents the inhomogeneity of field conditions by pooling, homogenising and sieving samples, without fear of obtaining unrepresentative CO2 flux measurements caused by the disruption of soil architecture. Keywords CO2 flux . Respiration . Homogenisation . Land use . Disturbance
1 Introduction CO2 flux from soil not containing plant roots represents the heterotrophic respiration of soil organisms (Gabriel and Kellman 2011). Soil respiration releases more CO2 into the atmosphere annually than all anthropogenic sources combined (Marland 2008) and a small change in CO2 flux from soils, globally, can greatly alter the concentration of atmospheric CO2 and influence our climate (Schurgers et al. 2018). Measurement of soil respiration is therefore important for quantifying the flux of CO2 to the atmosphere from soils. Soil CO2 flux also represents the activity of soil biological communities, thereby serving as a valuable indicator of soil health (McGowen et al. 2018). Soil respiration measurements undertaken in the field and laboratory often yield contrasting results (Davidson et al. 1998). CO2 flux measured at a single location in situ may * Tom Sizmur [email protected] 1
Department of Geography and Environmental Science, University of Reading, Reading, UK
not be representative due to soil heterogeneity at the field scale. Excavation of soil, followed by ex situ measurement of soil respiration under controlled conditions, is often performed to compare soils or test specific hypotheses (Gutinas et al. 2013; Zhou et al. 2014; Bao et al. 2016; Yan et al. 2017), while minimizing confounding factors. Whereas in
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