ARS | Publication request: ASSESSMENT OF FUNGAL AND BACTERIAL CONTRIBUTIONS TO SOIL C CYCLING

Submitted to: Microbial Ecology International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: February 6, 2001
Publication Date: N/A

Technical Abstract: Fungi and bacteria govern much of the C cycling in soil. The two groups of organisms differ in the ways through which they transform C, the forms in which C are stored, and in the longevity of the newly stored soil C. We hypothesized that increased fungal to bacterial ratios would enhance the longevity of C in soil. To measure these ratios in soil we used the selective inhibition technique using captan and oxytetracycline hydrochloride as the fungicide and bactericide. The procedure was applied to two contrasting soils from each of five different ecotypes. We observed, in some soils, evidence of non-target inhibition. For example, in one prairie soil, the non-target inhibition was 42% of the total soil respiration. In such cases, a potential range of ratios can be determined, within which the true value lies; however, reducing non-target inhibition will give closer estimates of the actual ratios. The procedure was refined by: 1) surveying novel antibiotics, 2) determining which pairs of antibiotics were most effective, and 3) choosing the best concentration of each antibiotic for a soil. We report here on these findings and discuss the relative metabolic capabilities of the two groups of organisms.