Does the presence of glomalin relate to reduced water infiltration through hydrophobicity?

Abstract

I. M. 2004. Does the presence of glomalin relate to reduced water infiltration through hydrophobicity? Can. J. Soil Sci. 84: 365-372. The resilience and stability of the physical structure of soil impacts directly on all soil processes, mediating microbial activity and defining the flow pathways between the soil ecosystem, waterways and the atmosphere. The effect of the presence of the glycoprotein glomalin exuded from Arbuscular Mycorrhzal (AM) fungi, on soil hydrophobicity is presented. A possible role for glomalin as improving soil structural stability is important in the context of soil protection. Using total glomalin, together with measurements of soil hydrophobicity, we investigate the spatial correlations between the two measurements in the presence and absence of pea roots. Whilst AM fungi were visible within roots (up to 52% root length colonization), no differences in glomalin concentration between planted and unplanted controls were observed. The presence and amount of glomalin did not correspond to the presence or level of hydrophobicity in soil. We discuss these results in relation to AM fungal-glomalin interactions, soil structure and root exudation.Key words: Glomalin, water infiltration, mycorrhizae, soil structure, hydrophobic Feeney, D. S., Daniell, T., Hallett, P. D., Illian, J., Ritz, K. et Young, I. M. 2004. La glomaline explique-t-elle la baisse de l'infiltration d'eau attribuable à l'hydrophobicité? Can. J. Soil Sci. 84: 365-372. La résilience et la stabilité de la structure physique du sol influent directement sur les mécanismes pédologiques en favorisant l'activité de la microflore et en régissant les flux entre l'écosystème tellurique, les cours d'eau et l'atmosphère. Les auteurs ont examiné l'incidence de la glomaline, une glycoprotéine extraite des mycorhizes à arbuscules (MA), sur l'hydrophobicité du sol. La glomaline pourrait stabiliser la structure du sol davantage, ce qui en accroîtrait l'importance pour la protection des sols. Les auteurs ont étudié les corrélations spatiales entre la concentration totale de glomaline et l'hydrophobicité du sol avec et sans racines de pois. Si les MA sont visibles sur les racines (colonisation de jusqu'à 52 % du système racinaire), on n'observe aucune variation de la concentration de glomaline entre les parcelles cultivées et les parcelles témoins qui ne l'étaient pas. La présence et la quantité de glomaline ne présentent aucune correspondance avec l'hydrophobicité du sol et son importance. Les auteurs analysent leurs résultats en fonction des interactions entre les MA et la glomaline, la structure du sol et l'exsudation des racines.

Biological and chemical factors controlling the patchy distribution of soil water repellency among plant species in a Mediterranean semiarid forest

“…Similar relationships for GRSP and ergosterol were obtained by Young et al (2012) in two different ecosystems: grassland and an arable soil. On the other hand, under controlled laboratory conditions in which a specific AM fungus was introduced, Feeney et al (2004) and Hallett et al (2009) did not find that link with glomalin and ergosterol respectively. The reason might lie in our analytical method (Bradford protein assay).…”

“…On the other hand, research highlights the point that the relationship between WR and plants may not always be direct: a group of fungi and microorganisms, which might be associated with specific plants, could also contribute to soil hydrophobicity through their products or by processing organic material (Feeney et al, 2004;Hallett and Young, 1999;Morales et al, 2010;White et al, 2000). In concrete, fungal hyphae, glomalin related soil protein and more recently ergosterol are being studied to understand their influence on the development of soil WR (Rillig, 2005;Rillig et al, 2010;Young et al, 2012).…”

“…The importance of the presence of GRSP relates to its supposed hydrophobic properties. Results on the influence of GRSP differ, so that the question is still unclear (Feeney et al, 2004;Young et al, 2012). Ergosterol is a specific component of fungal membranes and the major sterol in most filamentous fungi (Van den Bossche, 1990).…”

A brief overview of the causes, impacts and amelioration of soil water repellency - a review

“…There is growing interest in the compound glomalin in soil science as its highly adhesive and hydrophobic properties are hypothesised to be a major driver in pore structure stability (Wright & Upadhyaya 1998). However, work by Feeney et al (2004) showed that it was poorly related to water repellency. Capriel (1997) suggested using Diffuse-Reflectance Infrared Fourier Transform (DRIFT) Spectroscopy to detect hydrophobic compounds in soil.…”

Rise in CO2 affects soil water transport through repellency

“…Several studies have found microbial and plant biomass influences the development of water repellency in soil (Feeney et al 2004;Feeney et al 2006;Hallett et al 2003). Under elevated atmospheric CO 2 , we hypothesise that an increase in plant biomass will drive an increase in water repellency, either directly or through secondary microbial processes.…”