Author
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STAHL, PETER - IOWA STATE UNIVERSITY |
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Parkin, Timothy |
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Submitted to: Journal of Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/9/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Fungi are thread-like microorganisms that are important to the general quality of soil because they play a major role in the breakdown of plant residues and in the binding of soil particles into aggregates. However, accurate and reliable measurement of their presence is a problem. We conducted research to evaluate the use of a compound called ergosterol as an estimator of the amount of fungi in a soil. Ergosterol may be a particularly useful indicator of fungal growth because it is thought to be produced in soil only by fungi. Soil from seven sites in central Iowa was analyzed to determine ergosterol content and, for comparison, examined microscopically to estimate amounts of fungal hyphae. Statistical analysis of the data collected showed that the amount of ergosterol in the soils was significantly related to the amount of fungal hyphae present. Based on detailed analysis of the data we collected, we developed a method to estimate the amount of fungi in a soil based on the ergosterol content of that soil. A preliminary test of this technique, using data collected by other researchers, support the use of our method. This work is important because it provides a new means to estimate fungal presence in soil which will contribute to further understanding the role of fungi in soil quality and how agricultural management practices affect these important microorganisms. Technical Abstract: A study was conducted to add to our understanding of the relationship between amounts of fungi and ergosterol in soil and to further evaluate the use of ergosterol as an indicator of soil fungal biomass. Soils from seven sites in central Iowa were analyzed for ergosterol content, total fungal hyphal length (living and nonliving, using calcofluor as stain), and living fungal hyphal length (using fluorescein diacetate as stain) to: 1) Determine how soil ergosterol concentration correlates with total fungal hyphal length and living fungal hyphal length; and 2) Determine an approximate value for ergosterol concentration in living fungal biomass present in soil. Correlation significance tests and analysis of variance indicated highly significant positive correlation between soil ergosterol content and both measures of hyphal length but regression analysis demonstrated only a moderate degree of linear correlation between these variables (coefficients of linear correlation, r=0.638 to 0.874). Calculated values for ergosterol concentration in living fungal biomass present in the soils examined ranged from 5-31 mg ergosterol g**-1 living fungal biomass. Data indicate that the wide range in specific ergosterol content of living fungal biomass in soils is related to the total amount of fungal hyphae (living and nonliving) in a soil. We propose a method to estimate living fungal biomass from soil ergosterol content which compensates for the variability in fungal ergosterol concentrations by accounting for this relationship. A preliminary evaluation of this approach using independent data from the literature provide support for this method, in that a high correlation (r2=.999) between predicted and measured living fungal biomass was observed. |
