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Contribution of Lolium perenne rhizodeposition to carbon turnover of pasture soil (1999)

Kuzyakov, Y. ; Kretzschmar, A. ; Stahr, K.

Springer

Plant and soil 213 (1999), S. 127-136

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ISSN: 1573-5036

Keywords: Carbon turnover ; Lolium perenne ; rhizodeposition ; rhizosphere ; root respiration ; 14C pulse labelling

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Carbon rhizodeposition and root respiration during eight development stages of Lolium perenne were studied on a loamy Gleyic Cambisol by 14CO2 pulse labelling of shoots in a two compartment chamber under controlled laboratory conditions. Total 14CO2 efflux from the soil (root respiration, microbial respiration of exudates and dead roots) in the first 8 days after 14C pulse labelling decreased during plant development from 14 to 6.5% of the total 14C input. Root respiration accounted for was between 1.5 and 6.5% while microbial respiration of easily available rhizodeposits and dead root remains were between 2 and 8% of the 14C input. Both respiration processes were found to decline during plant development, but only the decrease in root respiration was significant. The average contribution of root respiration to total 14CO2 efflux from the soil was approximately 41%. Close correlation was found between cumulative 14CO2 efflux from the soil and the time when maximum 14CO2 efflux occurred (r=0.97). The average total of CO2 Defflux from the soil with Lolium perenne was approximately 21 μg C-CO2 d−1 g−1. It increased slightly during plant development. The contribution of plant roots to total CO2 efflux from the soil, calculated as the remainder from respiration of bare soil, was about 51%. The total 14C content after 8 days in the soil with roots ranged from 8.2 to 27.7% of assimilated carbon. This corresponds to an underground carbon transfer by Lolium perenne of 6–10 g C m−2 at the beginning of the growth period and 50–65 g C m−2 towards the end of the growth period. The conventional root washing procedure was found to be inadequate for the determination of total carbon input in the soil because 90% of the young fine roots can be lost.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1004566027237

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Permeationsuntersuchungen an stabilisierten Schaumlamellen (1979)

Wolf, F. ; Kretzschmar, A. ; Reichel, H.

Weinheim : Wiley-Blackwell

Acta Polymerica 30 (1979), S. 426-431

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ISSN: 0323-7648

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Description / Table of Contents: The time-dependence of the permeation of methanol vapour through tenside-alginate foam lamels was determined by measuring the permeation, diffusion and solubility coefficients. Steady-state transport was found to occur only within narrow time limits. The agreement of calculated and experimental relationships between the coefficients suggest solution diffusion as proposed by BARRER. The transport mechanism can be explained by the place exchange theory and by the cluster theory according to LUCK.

Notes: Für Tensid/Alginat-Schaumlamellen wurde der Durchtritt von Methanoldampf an Hand der Permeations-, Diffusions-und Löslichkeitskoeffizienten in Abhängigkeit von der Zeit ermittelt. Stationäre Transportzustände existieren nur in engen Zeitintervallen. Aus der Übereinstimmung zwischen den berechneten und experimentell ermittelten Koeffizienten-Beziehungen wird auf eine Lösungsdiffusion nach BARRER geschlossen. Der Transportmechanismus kann auf der Grundlage der Platzwechseltheorie sowie der Cluster-Theorie nach LUCK gedeutet wurden.

Additional Material: 7 Ill.