Differential effects of wetting and drying on soil CO2 concentration and flux in near-surface vs. deep soil layers

Min, Kweon Sik; Berhe, Asmeret Asefaw; Khôi, Châu Minh; Asperen, Hella van; Gillabel, Jeroen; Six, Johan

doi:10.1007/s10533-020-00658-7

Cited by 33 publications

(18 citation statements)

References 59 publications

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“…We observed a consistent positive effect of assay temperature on soil respiration within and across chronosequences. Such results agree with previous literature addressing the effects of temperature on soil organic matter decomposition and soil respiration rates Kirschbaum, 2006;Lloyd & Taylor, 1994;Min et al, 2020).…”

Section: Discussionsupporting

confidence: 92%

Temperature Increases Soil Respiration Across Ecosystem Types and Soil Development, But Soil Properties Determine the Magnitude of This Effect

et al. 2021

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Soil carbon losses to the atmosphere, via soil heterotrophic respiration, are expected to increase in response to global warming, resulting in a positive carbon-climate feedback.Despite the well-known suite of abiotic and biotic factors controlling soil respiration, much less is known about how the magnitude of soil respiration responses to temperature changes over soil development and across contrasting soil properties. Here, we investigated the role of soil development stage and soil properties in driving the responses of soil heterotrophic respiration to increasing temperatures. We incubated soils from eight chronosequences ranging in soil age from hundreds to million years, and encompassing a wide range of vegetation types, climatic conditions, and chronosequences origins, at three assay temperatures (5, 15 and 25ºC). We found a consistent positive effect of assay temperature on soil respiration rates across the eight chronosequences evaluated.However, soil properties such as organic carbon concentration, texture, pH, phosphorus content, and microbial biomass determined the magnitude of temperature effects on soil respiration. Finally, we observed a positive effect of soil development stage on soil respiration that did not alter the magnitude of assay temperature effects. Our work reveals that key soil properties alter the magnitude of the positive effect of temperature on soil respiration found across ecosystem types and soil development stages. This information is essential to better understand the magnitude of the carbon-climate feedback, and thus to establish accurate greenhouse gas emission targets.

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Section: Discussionsupporting

confidence: 92%

Temperature Increases Soil Respiration Across Ecosystem Types and Soil Development, But Soil Properties Determine the Magnitude of This Effect

et al. 2021

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“…4). Our results are in line with recent findings that microbial C transformations and associated CO2 fluxes in deep soils (70 cm) are substantial (Min et al, 2020), microbial activities below 30 cm can be as high (Jones et al, 2018) or higher (Stone et al, 2014) than those at the surface. Also, a recent study revealed that root exudates from switchgrass enhanced microbial production of extracellular polymeric substances and soil C stability along 120 cm of soil profiles (Sher et al, 2020).…”

Section: Discussionsupporting

confidence: 93%

“…However, most soil C dynamics research so far has focused on the top 30 cm of soil, where soil C concentrations are highest (Jobbágy and Jackson, 2000; Kögel-Knabner et al, 2008). Recent studies highlight that surface soil (< 30 cm) and deep soil (> 30 cm) C pools respond differently to changes in environmental conditions (Berhe et al, 2008; Fierer et al, 2003a; Jia et al, 2019; Min et al, 2020; Pries et al, 2017). At the surface, variation in abiotic factors such as temperature and moisture can influence microbial transformation of soil organic C. However, in deeper soil layers, relatively constant environmental conditions, increased mineral interactions, and lower microbial biomass, combined with distinct microbial community composition, may alter the capacity for microbial C transformation relative to the surface (Rumpel et al, 2012; Rumpel and Kögel-Knabner, 2011).…”

Section: Introductionmentioning

confidence: 99%

Soil depth gradients in microbial growth kinetics under deeply- vs. shallow-rooted plants

Kong

Slessarev

et al. 2021

Preprint

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Climate-smart land management practices that replace shallow-rooted annual crop systems with deeply-rooted perennial plants can contribute to soil carbon sequestration. However, deep soil carbon accrual may be influenced by active microbial biomass and their capacity to assimilate fresh carbon at depth. Incorporating active microbial biomass, dormancy and growth in models can improve our ability to predict the capacity of soil to store carbon. But, so far, the microbial parameters that are needed for such modeling are poorly constrained, especially in deep soil layers. Here, we investigated whether a change in crop rooting depth affects microbial growth kinetics in deep soils compared to surface soils. We used a lab incubation experiment and growth kinetics model to estimate how microbial parameters vary along 240 cm of soil depth in profiles under shallow- (soy) and deeply-rooted plants (switch grass) 11 years after plant cover conversion. We also assessed resource origin and availability (total organic carbon, 14C, dissolved organic carbon, specific UV absorbance, total nitrogen, total dissolved nitrogen) along the soil profiles to examine associations between soil chemical and biological parameters. Even though root biomass was higher and rooting depth was deeper under switch grass than soy, resource availability and microbial growth parameters were generally similar between vegetation types. Instead, depth significantly influenced soil chemical and biological parameters. For example, resource availability, and total and relative active microbial biomass decreased with soil depth. Decreases in the relative active microbial biomass coincided with increased lag time (response time to external carbon inputs) along the soil profiles. Even at a depth of 210-240 cm, microbial communities were activated to grow by added resources within a day. Maximum specific growth rate decreased to a depth of 90 cm and then remained consistent in deeper layers. Our findings show that > 10 years of vegetation and rooting depth changes may not be long enough to alter microbial growth parameters, and suggest that at least a portion of the microbial community in deep soils can grow rapidly in response to added resources. Our study determined microbial growth parameters that can be used in models to simulate carbon dynamics in deep soil layers.

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“…Based on these high frequency measurements of the soil CO 2 concentration, a hysteresis loop was found when plotting the CO 2 concentration as a function of the soil temperature in a high-altitudinal, semi-arid forest soil (Riveros-Iregui et al 2007). A very similar relationship between soil CO 2 concentration and soil temperature was also observed in a temperate pine plantation (Zhang et al 2015) and Mediterranean cropland soils (Min et al 2020). In addition, several authors reported a hysteresis loop when plotting the CO 2 efflux as a function of soil temperature (Parkin and Kaspar 2003;Gaumont-Guay et al 2006;Ruehr et al 2010;Jia et al 2013;Wang et al 2014;Song et al 2015;Zhang et al 2015).…”

Section: Introductionmentioning

confidence: 60%

Temperature controls diel oscillation of the CO2 concentration in a desert soil

Spohn

Holzheu

2021

Biogeochemistry

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The diel dynamic of the CO2 concentration in soils in relation to temperature is not yet fully understood. Air temperature might control the soil CO2 concentration due to thermal convective venting at sites experiencing large temperature differences between the atmosphere and the soil. Therefore, the objective of this study was to determine the soil CO2 concentration and its temporal dynamic in a deep desert soil in relationship to soil and air temperature based on high frequency measurements. For this purpose, CO2 concentration and temperature were measured in six soil depths (ranging from 15 to 185 cm) in a coarse-textured desert soil in the North of Chile every 60 min together with precipitation and air temperature for one year. The mean CO2 concentration calculated across the whole measuring period increased linearly with soil depth from 463 ppm in 15 cm to 1542 ppm in 185 cm depth. We observed a strong diel oscillation of the CO2 concentration that decreased with soil depth and a hysteretic relationship between the topsoil CO2 concentration and both air and soil temperature. The Rayleigh-Darcy number calculated for different times indicates that thermal convective venting of the soil occurred during the night and in the early morning. A small precipitation event (4 mm) increased the CO2 concentrations in 15, 30, and 50 cm depths for several days but did not alter the amplitude of the diel oscillation of the CO2 concentration. The diel oscillation of the CO2 concentration and the hysteretic relationship between soil CO2 concentration and air temperature were likely caused by thermal convection, leading to transport of CO2-rich air from the soil to the atmosphere at night. In conclusion, our results indicate that the soil CO2 concentration can be largely controlled by convection caused by temperature differences, and not only by diffusion. The results have important implications as they provide further evidence that thermal convective venting contributes to gas exchange at sites experiencing large temperature differences between the atmosphere and the soil, which is relevant for soil chemical reactions.

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Differential effects of wetting and drying on soil CO2 concentration and flux in near-surface vs. deep soil layers

Cited by 33 publications

References 59 publications

Temperature Increases Soil Respiration Across Ecosystem Types and Soil Development, But Soil Properties Determine the Magnitude of This Effect

Temperature Increases Soil Respiration Across Ecosystem Types and Soil Development, But Soil Properties Determine the Magnitude of This Effect

Soil depth gradients in microbial growth kinetics under deeply- vs. shallow-rooted plants

Temperature controls diel oscillation of the CO2 concentration in a desert soil

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