Gas diffusion and air-filled porosity: Effect of some oversize fragments in growing media

Caron, Jean; Rivière, L.M.; Guillemain, Gilles

doi:10.4141/s03-086

Cited by 37 publications

(27 citation statements)

References 19 publications

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“…Most D s / D o values in this study (Tables 2–4) were in agreement with those reported in other studies for sandy soils and for similar θ a (Lai et al ., 1976; Jellick & Schnabel, 1986; Shimamura, 1992; Ball et al ., 1994; van Bochove et al ., 1998) and for organic soils (King & Smith, 1987; Caron et al ., 2005). A few values were larger than in other studies.…”

Section: Resultsmentioning

confidence: 99%

Soil‐gas diffusivity in large soil monoliths

Lange

Allaire

Rolston

2009

European J Soil Science

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The variability of gas diffusion in soil is not well known, but is important for assessing greenhouse gas emissions, soil decontamination, oxidation in soil and plant and root respiration. The goal of this study was to assess small-scale variability of the relative soil-gas diffusivity (D s / D o , m soil air m −1 soil ) using large intact soil monoliths and to compare D s / D o calculation methods. Neon (Ne) was maintained constant at the lower boundary of three monoliths of two soils (a sand and an organic soil). Ne concentration was measured at large spatial and temporal frequencies. Calculation methods included the use of average concentration, and average D s / D o per horizon, per section, or for the entire soil profile. Considering all sections of the monoliths, D s / D o varied from 3.5 × 10 −3 to 1.2 × 10 −1 for the A p horizon and from 4.8 × 10 −3 to 8.3 × 10 −1 for the B f horizon in the sand and from 1.0 × 10 −3 to 7.9 × 10 −3 for the O hp horizon and from 2.4 × 10 −4 to 7.7 × 10 −2 for the O f horizon in the organic soil. For the entire soil profile, variations in D s / D o between monoliths reached 125% in the sand and 56% in the organic soil. The D s / D o calculation method influenced the apparent variability (CV) of D s / D o and, to a lesser extent, D s / D o values of the overall soil profile. Differences in D s / D o between monoliths could not be explained solely by the variability of total soil porosity and air-filled porosity. Soil macroporosity (cracks and earthworm burrows) and layering greatly influenced variability of gas movement. Thus, the choice of sampling procedure, calculation method and modelling must be governed by the scale of the processes of interest and soil variability attributes.

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Section: Resultsmentioning

confidence: 99%

Soil‐gas diffusivity in large soil monoliths

Lange

Allaire

Rolston

2009

European J Soil Science

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“…Research on growing media has long neglected to consider D s /D o in substrates, relying only on u a , and assuming g to be constant. However, Allaire et al (1996), Caron and Nkongolo (2004), and Caron et al (2005b) showed that g appears to vary considerably at a same u a between different susbtrates . The reason for this is that although large particles improve u a by interacting with adjacent smaller particles to create macropores, they may also create barriers if they are impermeable to gaseous diffusion (Nkongolo and Caron 1999).…”

Section: Methodological Approach Used Tomentioning

confidence: 99%

Identifying appropriate methodology to diagnose aeration limitations with large peat and bark particles in growing media

Caron¹,

Morel²,

Rivière³

et al. 2010

Can. J. Soil. Sci.

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Caron, J., Morel, P., Rivie`re, L.-M. and Guillemain, G. 2010. Identifying appropriate methodology to diagnose aeration limitations with large peat and bark particles in growing media. Can. J. Soil Sci. 90: 481Á494. Large-sized particles (coarse peat, bark or sawdust) are often added to growing media to improve substrate aeration properties (gas storage and exchange). Recent studies have shown that large fragments mixed with fines may create barriers that restrict gas diffusion or create competition for oxygen even if they improve air storage. An experiment was carried out to compare the growth performances of growing media containing large fragments and to assess their aeration status using different methods. Different mixes were made of a fine sphagnum peat (average size 2.4 mm) and a coarse (1Á2, 2Á4, 4Á6, 6Á10, and 10Á20 mm particles) sphagnum peat or bark (2Á4 and 10Á20 mm). These substrates had different aeration properties and were used to grow Poinsettia and Impatiens 'New Guinea' in a greenhouse, resulting in differences in plant growth. The results show that air-filled porosity remained relatively unaffected by fragment size. Gas relative diffusivity differed significantly between treatments and was highest in the mix with the 2Á4 mm particles and diminished rapidly as fragment size increased from 4 to 20 mm or decreased to 1Á2 mm. Diffusivity was clearly lower in the bark/peat mixes but showed the same trend with coarse fragments. Root and shoot growth parameters were significantly and positively correlated to gas relative diffusivity. Moreover, the growth reduction observed in the bark/peat mixes relative to pure peat was most likely linked to limited gas exchange. Air-filled porosity assessments performed in situ (in the pot itself) or prior to potting, in cylinders, gave inconsistent results or were not significantly correlated to plant growth, indicating that aeration limitations are better diagnosed with gas diffusivity in growing media.Key words: Air-filled porosity, gas relative diffusivity, gas diffusion, peat substrates, bark, Euphorbia pulcherima, Impatiens ()novae-guinea)Caron, J., Morel, P., Rivie`re, L.-M. et Guillemain, G. 2010. Identifying appropriate methodology to diagnose aeration limitations with large peat and bark particles in growing media. Can. J. Soil Sci. 90: 481Á494. Des fragments de fortes tailles (tourbe, e´corce ou sciure brute) sont souvent ajoute´s aux substrats de culture de serres ou de pe´pinie`res pour ame´liorer leurs proprie´te´s d'ae´ration (stockage et e´change de gaz). Les e´tudes re´centes ont prouve´que les larges fragments me´lange´s aux fins peuvent cre´er des barrie`res qui limitent la diffusion de gaz ou cre´ent une compe´tition pour l'oxyge`ne meˆme s'ils ame´liorent le stockage d'air. Deux expe´riences ont e´te´effectue´es pour comparer les performances en serre de diffe´rents milieux de culture contenant des fragments larges et pour e´valuer leur statut d'ae´ration selon diffe´rentes me´thodes. Ces substrats ont e´te´faits d'un me´lange d'un volume de t...

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“…The determination of the oxygen diffusion coefficient played no major role in the analysis of growing media yet [16]. Investigations described in the literature are usually based on mineral soils [4,17].…”

Section: Introductionmentioning

confidence: 99%

Effect of Air Content on the Oxygen Diffusion Coefficient of Growing Media

Schmitz¹,

Anlauf²,

Rehrmann³

2013

AJPS

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An important parameter for describing oxygen availability in growing media is the air capacity, but this parameter does not include any information about the gas exchange with the surrounding atmosphere. The oxygen diffusion coefficient fulfills this requirement and may be better suited as a characteristic parameter to describe the oxygen regime. The measurement of the gas diffusion coefficient is a common method to describe the oxygenation in mineral soils, but this method has not been studied well on growing media yet. In this investigation four different growing media were used to measure the oxygen diffusion coefficient at two different bulk densities and four different water tensions in the laboratory. The effect of density and water tension on the oxygen diffusion coefficient in different growing media and the dependence on air content were investigated. The results show that both water tension and density have a major influence on oxygen diffusion. With increasing density and moisture content, a decrease of the oxygen diffusion coefficient can be observed. Between the substrates there are no significant differences regarding the oxygen diffusion coefficient at the same air content. Based on the oxygen diffusion coefficients of the substrates, the models describing the dependence of gas diffusion coefficients to air content in the literature were tested for the transferability to growing media. The Moldrup model [1] shows the best fit. The fit can be slightly further improved by modifying the tortuosity parameter.

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Gas diffusion and air-filled porosity: Effect of some oversize fragments in growing media

Cited by 37 publications

References 19 publications

Soil‐gas diffusivity in large soil monoliths

Soil‐gas diffusivity in large soil monoliths

Identifying appropriate methodology to diagnose aeration limitations with large peat and bark particles in growing media

Effect of Air Content on the Oxygen Diffusion Coefficient of Growing Media

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