Statistical analysis of reduction in tensile strength of cotton strips as a measure of soil microbial activity

Correll, Raymond L., Harch, Bronwyn, Kirkby, Clive A., O'Brien, K., & Pankhurst, Clive E. (1997) Statistical analysis of reduction in tensile strength of cotton strips as a measure of soil microbial activity. Journal of Microbiological Methods, 31(1-2), pp. 9-17.

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The cotton strip assay (CSA) is an established technique for measuring soil microbial activity. The technique involves burying cotton strips and measuring their tensile strength after a certain time. This gives a measure of the rotting rate, R, of the cotton strips. R is then a measure of soil microbial activity. This paper examines properties of the technique and indicates how the assay can be optimised. Humidity conditioning of the cotton strips before measuring their tensile strength reduced the within and between day variance and enabled the distribution of the tensile strength measurements to approximate normality. The test data came from a three-way factorial experiment (two soils, two temperatures, three moisture levels). The cotton strips were buried in the soil for intervals of time ranging up to 6 weeks. This enabled the rate of loss of cotton tensile strength with time to be studied under a range of conditions. An inverse cubic model accounted for greater than 90% of the total variation within each treatment combination. This offers support for summarising the decomposition process by a single parameter R. The approximate variance of the decomposition rate was estimated from a function incorporating the variance of tensile strength and the differential of the function for the rate of decomposition, R, with respect to tensile strength. This variance function has a minimum when the measured strength is approximately 2/3 that of the original strength. The estimates of R are almost unbiased and relatively robust against the cotton strips being left in the soil for more or less than the optimal time. We conclude that the rotting rate X should be measured using the inverse cubic equation, and that the cotton strips should be left in the soil until their strength has been reduced to about 2/3.

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12 citations in Scopus
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12 citations in Web of Science®

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ID Code: 72780
Item Type: Journal Article
Refereed: Yes
Additional Information: Cited By (since 1996):12 Export Date: 26 May 2014 Source: Scopus CODEN: JMIMD
Additional URLs:
Keywords: Cellulose decomposition, Cotton strip assay (CSA), Weibull distribution, cellulose, article, conditioning, controlled study, cotton, decomposition, humidity, measurement, microbiology, nonhuman, priority journal, quantitative assay, soil microflora, statistical analysis, tensile strength, Gossypium hirsutum
DOI: 10.1016/S0167-7012(97)00080-8
ISSN: 0167-7012
Divisions: Current > QUT Faculties and Divisions > Science & Engineering Faculty
Deposited On: 12 Jun 2014 23:22
Last Modified: 12 Jun 2014 23:22

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