Gas pooling: A sampling technique to overcome spatial heterogeneity of soil carbon dioxide and nitrous oxide fluxes

Arias-Navarro, Cristina; Díaz‐Pinés, Eugenio; Kiese, Ralf; Rosenstock, Todd S.; Rufino, Mariana C.; Stern, David I.; Neufeldt, Henry; Verchot, Louis; Butterbach‐Bahl, Klaus

doi:10.1016/j.soilbio.2013.08.011

Cited by 57 publications

(27 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…No ambient air was injected to correct for the change in pressure associated with the removal of air sample. We used four soil core replicates and pooled the samples as per Arias‐Navarro et al [] for each flux calculation; i.e., a 10 mL gas sample was taken from each individual jar headspace at 15 min intervals (0, 15, 30, and 45 min after chamber closure) with the same syringe at each time interval resulting in a 40 mL composite sample. The first 20 mL of the sample was used to flush a 10 mL glass vial, which was filled with the remaining 20 mL creating overpressure to minimize the risk of contamination by ambient air.…”

Section: Methodsmentioning

confidence: 99%

Spatial variability of soil N₂O and CO₂ fluxes in different topographic positions in a tropical montane forest in Kenya

et al. 2017

View full text Add to dashboard Cite

Quantifying and understanding the small‐scale variability of nitrous oxide (N2O) and carbon dioxide (CO2) emission are essential for reporting accurate ecosystem greenhouse gas budgets. The objective of this study was to evaluate the spatial pattern of soil CO2 and N2O emissions and their relation to topography in a tropical montane forest. We measured fluxes of N2O and CO2 from 810 sampling locations across valley bottom, midslope, and ridgetop positions under controlled laboratory conditions. We further calculated the minimum number of samples necessary to provide best estimates of soil N2O and CO2 fluxes at the plot level. Topography exhibited a major influence on N2O emissions, with soils at midslope position emitting significantly less than at ridgetops and valley bottoms, but no consistent effect of topography on soil CO2 emissions was found. The high spatial variation of N2O and CO2 fluxes was further increased by changes in vegetation and soil properties resulting from human disturbance associated with charcoal production. Soil N2O and CO2 fluxes showed no spatial pattern at the plot level, with “hot spots” strongly contributing to the total emissions (10% of the soil cores represented 73 and 50% of the total N2O and CO2 emissions, respectively). Thus, a large number of samples are needed to obtain robust estimates of N2O and CO2 fluxes. Our results highlight the complex biogeochemical cycling in tropical montane forests, and the need to carefully address it in research experiments to robustly estimate soil CO2 and N2O fluxes at the ecosystem scale.

show abstract

Section: Methodsmentioning

confidence: 99%

Spatial variability of soil N₂O and CO₂ fluxes in different topographic positions in a tropical montane forest in Kenya

et al. 2017

View full text Add to dashboard Cite

show abstract

“…We removed 10 ml of gas from each chamber immediately upon closure and then after 15, 30 and 45 min. The five gas samples from each of the five chambers were then pooled for analysis as explained by (Arias-Navarro et al, 2013). During gas sampling, soil water content at a depth of 0.05mwasmeasured using a digital Pro-Check sensor (Decagon Devices, Inc. Pullman,WA99163, US),while soil and chamber temperatures were taken with a digital probe thermometer (TFA Dostmann GmbH, Zum Ottersberg, Germany).…”

Section: Gas Sampling and Analysismentioning

confidence: 99%

Management intensity controls soil N2O fluxes in an Afromontane ecosystem

Wanyama

Pelster²,

Arias-Navarro³

et al. 2018

Science of The Total Environment

View full text Add to dashboard Cite

Studies that quantify nitrous oxide (NO) fluxes from African tropical forests and adjacent managed land uses are scarce. The expansion of smallholder agriculture and commercial agriculture into the Mau forest, the largest montane forest in Kenya, has caused large-scale land use change over the last decades. We measured annual soil NO fluxes between August 2015 and July 2016 from natural forests and compared them to the NO fluxes from land either managed by smallholder farmers for grazing and tea production, or commercial tea and eucalyptus plantations (n=18). Air samples from 5 pooled static chambers were collected between 8:00am and 11:30am and used within each plot to calculate the gas flux rates. Annual soil NO fluxes ranged between 0.2 and 2.9kgNhayr at smallholder sites and 0.6-1.7kgNhayr at the commercial agriculture sites, with no difference between land uses (p=0.98 and p=0.18, respectively). There was marked variation within land uses and, in particular, within those managed by smallholder farmers where management was also highly variable. Plots receiving fertilizer applications and those with high densities of livestock showed the highest NO fluxes (1.6±0.3kgNO-Nhayr, n=7) followed by natural forests (1.1±0.1kgNO-Nhayr, n=6); although these were not significantly different (p=0.19). Significantly lower fluxes (0.5±0.1kgNhayr, p<0.01, n=5) were found on plots that received little or no inputs. Daily soil NO flux rates were not correlated with concurrent measurements of water filled pore space (WFPS), soil temperature or inorganic nitrogen (IN) concentrations. However, IN intensity, a measure of exposure of soil microbes (in both time and magnitude) to IN concentrations was strongly correlated with annual soil NO fluxes.

show abstract

“…4.3 The concept of gas pooling. ( a ) Gas pooling across chambers for a given sampling time, ( b ) gas sample mixing within the syringe, ( c ) transfer of the gas sample to a vial, ( d ) four vials for four sampling times and fi ve chambers, ( e ) air sample analysis via gas chromatography (for further details see Arias-Navarro et al 2013 ) turnover processes due to small-scale differences in soil properties, soil environmental conditions, and microbial activity and diversity. Overcoming spatial variability effects on GHG fl uxes is a major challenge, specifi cally for highly diverse smallholder systems.…”

Section: Chambers and Spatial Variability Of Ghg Fluxesmentioning

confidence: 99%

Methods for Measuring Greenhouse Gas Balances and Evaluating Mitigation Options in Smallholder Agriculture

Rosenstock¹,

Rufino²,

Butterbach‐Bahl³

et al. 2016

View full text Add to dashboard Cite

Gas pooling: A sampling technique to overcome spatial heterogeneity of soil carbon dioxide and nitrous oxide fluxes

Cited by 57 publications

References 19 publications

Spatial variability of soil N₂O and CO₂ fluxes in different topographic positions in a tropical montane forest in Kenya

Spatial variability of soil N₂O and CO₂ fluxes in different topographic positions in a tropical montane forest in Kenya

Management intensity controls soil N2O fluxes in an Afromontane ecosystem

Methods for Measuring Greenhouse Gas Balances and Evaluating Mitigation Options in Smallholder Agriculture

Contact Info

Product

Resources

About

Gas pooling: A sampling technique to overcome spatial heterogeneity of soil carbon dioxide and nitrous oxide fluxes

Cited by 57 publications

References 19 publications

Spatial variability of soil N2O and CO2 fluxes in different topographic positions in a tropical montane forest in Kenya

Spatial variability of soil N2O and CO2 fluxes in different topographic positions in a tropical montane forest in Kenya

Management intensity controls soil N2O fluxes in an Afromontane ecosystem

Methods for Measuring Greenhouse Gas Balances and Evaluating Mitigation Options in Smallholder Agriculture

Contact Info

Product

Resources

About

Spatial variability of soil N₂O and CO₂ fluxes in different topographic positions in a tropical montane forest in Kenya

Spatial variability of soil N₂O and CO₂ fluxes in different topographic positions in a tropical montane forest in Kenya