Comparative effects of propylene oxide, sodium azide, and autoclaving on selected soil properties

• Published in: Soil biology & biochemistry Vol. 5; no. 4; pp. 409 - 414
• Main Authors: Skipper, Horace D., Westermann, Dale T.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1973
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/0038-0717(73)90067-9

Samples of soil (25 g) were treated with 1 or 2 ml of propylene oxide, 400 or 800 parts/10 6 of sodium azide, or autoclaved for 1.5 or 3.0 h. Soil sterilization was achieved by the propylene oxide and autoclaving treatments. Sodium azide inhibited the bacteria and actinomycetes and drastically reduced the fungal population. The autoclaving treatment decreased the soil pH 0.2 unit, while propylene oxide and sodium azide treatments increased it 0.5–1.1 units. Extractable manganous—Mn was increased 2- to 3-fold by all treatments except for a 90- to 120-fold increase in an autoclaved soil; extractable Ca was not affected; and the extractable K changes were slight. Total extractable N was increased 10–20 parts/10 6, and available P was generally increased by the treatments. Propylene oxide induced the least chemical alterations upon sterilization and is considered an appropriate sterilant to study chemical transformations in soils; but, germination and growth of wheat and alfalfa were retarded in propylene oxide treated soil.