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 labora tory. The effect of density and water tension on the oxygen diffusion coefficient in different growing media and the dependence on air content w ere investigated. The results show that both water tension and density have a major influ ence 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 depend ence 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.
P. Moldrup, T. Olesen, D. E. Rolston and T. Yamaguchi, “Modeling Diffusion and Reaction in Soils: Vii. Predicting Gas and Ion Diffusivity in Undisturbed and Sieved Soils,” Soil Science, Vol. 162, No. 9, 1997, pp. 632-640. doi:10.1097/00010694-199709000-00004
M. De Boodt and O. Verdonck, “The Physical Properties of the Substrates in Horticulture,” Acta Horticulturae, Vol. 26, 1972, pp. 37-44. http://www.actahort.org/books/26/26_5.htm
F. Göhler and H. D. Molitor, “Erdelose Kulturverfahren im Gartenbau,” Eugen Ulmer Verlag, Stuttgart, 2002.
M. Raviv and J. H. Lieth, “Soilless Culture-Theory and Practice,” Elsevier, Amsterdam, 2008.
R. Baas and M. G. Warmenhoven, “Alcohol Dehydrogenase Indicating Oxygen Deficiency in Chrysanthemum Grown in Mineral Media,” Acta Horticulturae, Vol. 401, 1995, pp. 273-282. http://www.actahort.org/books/401/401_33.htm
R. Anlauf, P. Rehrmann and H. Schacht, “Simulation of Water Uptake and Redistribution in Growing Media during Ebb-and-Flow Irrigation,” Journal of Horticulture and Forestry, Vol. 4, No. 1, 2012, pp. 8-21.
J. Caron and N. V. Nkongolo, “Aeration in Growing Media: Recent Developments,” Acta Horticulturae, Vol. 481, 1999, pp. 545-551. http://www.actahort.org/books/481/481_64.htm
J. Caron, P. Morel, L. M. Riviére and G. Guillemain, “Identifying Appropriate Methodology to Diagnose Aeration Limitations with Large Peat and Bark Particles in Growing Media,” Canadian Journal of Soil Science, Vol. 90, No. 3, 2010, pp. 481-494. doi:10.4141/CJSS09015
A. Wrede, “Untersuchungen zur Ermittlung der Kennwerte des Luftund Wasserhaushalts von Kultursubstraten,” Ph.D. Thesis, Hannover University, Hannover, 2010. http://edok01.tib.uni-hannover.de/edoks/e01dh01/331191490.pdf
H. G. Frede, “Der Gasaustausch des Bodens,” Göttinger Bodenkundliche Berichte, Vol. 87, 1986.
S. E. Allaire, J. Caron, J. Duchesne, L. E. Parent and J. A. Rioux, “Air-Filled Porosity, Gas Relative Diffusivity, and Tortuosity: Indices of Prunus x Cistena sp. Growth in Peat Substrates,” Journal of the American Society for Horticultural Science, Vol. 121, 1996, pp. 236-242. http://journal.ashspublications.org/content/121/2/236.full.pdf
M. Raviv, R. Wallach and T. J. Blom, “The Effect of Physical Properties of Soilless Media on Plant Performance: A Review,” Acta Horticulturae, Vol. 644, 2004, pp. 251-259. http://www.actahort.org/books/644/644_34.htm
L. M. Riviere and J. Caron, “Research on Substrates-State of the Art and Need for the Coming 10 Years,” Acta Horticulturae, Vol. 548, 2001, pp. 29-41. http://www.actahort.org/books/548/548_1.htm
N. C. Brady and R. R. Weil, “Elements of the Nature and Properties of Soils,” Prentice-Hall, London, 1999.
W. A. Jury and R. Horton, “Soil Physics,” John Wiley, Hoboeken, 2004.
J. Caron, L. M. Riviére and G. Guillemain, “Gas Diffusion and Air-Filled Porosity: Effect of Some Oversize Fragments in Growing Media,” Canadian Journal of Soil Science, Vol. 85, No. 1, 2005, pp. 57-65. doi:10.4141/S03-086
P. Moldrup, T. Olesen, S. Yoshikawa, T. Komatsu and D. E. Rolston, “Three-Porosity Model for Predicting the Gas Diffusion Coefficient in Undisturbed Soil,” Soil Science Society of America, Vol. 68, No. 3, 2004, pp. 750-759.
D. Hillel, “Environmental Soil Physics,” Academic Press, London, 1998.
K. Handreck and N. Black, “Growing Media for Ornamental Plants and Turf,” University of New South Wales Press, Sydney, 2002.
O. Verdonck and P. Demeyer, “The Influence of the Particle Sizes on the Physical Properties of Growing Media,” Acta Horticulturae, Vol. 644, 2004, pp. 99-101. http://www.actahort.org/books/644/644_10.htm
R. E. Sojka and H. D. Scott, “Aeration Measurement,” In: In: R. Lal, Ed., Encyclopedia of Soil Science, 2nd Edition, CRC Press, Rattan Lal, 2005. doi:10.1201/NOE0849338304.ch8
N. Gruda, T. Rocksch and U. Schmidt, “CO2-Concentration in Root Zone of Vegetables, Cultivated in Organic Substrates,” Acta Horticulturae, Vol. 801, 2005, pp. 1063-1068. http://www.actahort.org/books/779/779_64.htm
N. V. Nkongolo and J. Caron, “Bark Particle Size and Modification of the Physical Properties of Peat Substrate,” Canadian Journal of Soil Science, Vol. 79, No. 1, 1999, pp. 111-116. doi:10.4141/S96-084
J. Gliński and W. Stepniewski, “Soil Aeration and Its Role for Plants,” CRC Press, Boca Raton, 1985.
R. Lal and M. K. Shukla, “Principles of Soil Physics,” Marcel Dekker, Inc., New York/Basel, 2004.
P. Moldrup, T. Olesen, J. Gamst, P. Schjoenning, D. E. Rolston and T. Yamaguchi, “Predicting the Gas Diffusion Coefficient in Repacked Soil: Water-Induced Linear Reduction Model,” Soil Science Society of America, Vol. 64, No. 5, 2000, pp. 1588-1594. doi:10.2136/sssaj2000.6451588x
M. A. Mostafid, C. Shanka, P. T. Imhoff and R. Yazdani, “Gas Transport Properties of Compost-Woodchip and Green Waste for Landfill Biocovers and Biofilters,” Chemical Engineering Journal, Vol. 191, 2012, pp. 314-325. doi:10.1016/j.cej.2012.03.022
VDLUFA, “Bestimmung der Rohdichte (Volumengewicht) von gärtnerischen Erden und Substraten ohne Sperrige Komponenten. VDLUFA Methodenbuch, Band I, Die Untersuchung von Böden,” VDLUFA Verlag, Darmstadt, 1991.
DIN EN 13041, “Soil Improvers and Growing Media- Determination of Physical Properties-Dry Bulk Density, Air Volume, Water Volume, Shrinkage Value and Total Pore Space,” German Version EN 13041:2010, Deutsches Institut für Normung e.V., Beuth Verlag, 2010.
R. Gabriels and O. Verdonck, “Physical and Chemical Characterization of Plant Substrates: Towards a European Standardization,” Acta Horticulturae, Vol. 294, 1991, pp. 249-259. http://www.actahort.org/books/294/294_27.htm
DIN 11540, “Peats and Peat Products for Horticulture and Landscape Gardening-Test Methods, Properties, Specifications,” Deutsches Institut für Normung e.V., Beuth Verlag, 2005.
W. D. Kemper and R. C. Rosenau, “Aggregate Stability and Size Distribution,” In: A. Klute, Ed., Methods of Soil Analysis, Part 1 (2nd Edition), Agrononomy Monograph Nr. 9, American Dairy Science Association und Soil Science Society of America, Madison, 1986, pp. 425-441.
D. E. Rolston and P. Moldrup, “Gas Diffusivity,” In: A. Klute, Ed., Methods of Soil Analysis, Part 4, Soil Science Society of America, Madison, 2002, pp. 1089-1102.
R. Baas, G. Wever, A. J. Koolen, E. Tariku and K. J. Stol, “Oxygen Supply and Consumption in Soilless Culture: Evaluation OD an Oxygen Simulation Model for Cucumber,” Acta Horticulturae, Vol. 554, 2001, pp. 157-164. http://www.actahort.org/books/554/554_16.htm
J. Caron and N. V. Nkongolo, “Assessing Gas Diffusion Coefficients in Growing Media from in Situ Water Flow and Storage Measurements,” Vadose Zone Journal, Vol. 3, 2004, pp. 300-311. doi:10.2113/3.1.300
G. W. Snedecor and W. G. Cochran, “Statistical Methods,” Iowa State University Press, Ames, 1980.
Y. Rondot, “Effect of Water Content and Bulk Density on the Oxygen Diffusion in Horticultural Substrates (in German),” Diploma Thesis, Osnabrueck University of Applied Sciences, Osnabrueck, 2009.
D. Schmitz, “Effect of Bulk Density and Water Content of Different Growing Media on Oxygen Diffusion Coefficients (in German),” B.Sc. Thesis, Osnabrueck University of Applied Sciences, Osnabrueck, 2011.
P. Cannavo and J. C. Michel, “Peat Particle Size Effects on Spatial Root Distribution, and Changes on Hydraulic and Aeration Properties,” Scientia Horticulturae, Vol. 151, 2013, pp. 11-21. doi:10.1016/j.scienta.2012.12.021
J. A. King and K. A. Smith, “Gaseous Diffusion through Peat,” Journal of Soil Science, Vol. 38, No. 2, 1987, pp. 173-177. doi:10.1111/j.1365-2389.1987.tb02134.x
J. Caron, P. Morel and L. M. Riviére, “Aeration in Growing Media Containing Large Particle Size,” Acta Horticulturae, Vol. 548, 2001, pp. 229-234. http://www.actahort.org/books/548/548_25.htm