Laboratory experiments were conducted to determine the rate of decomposition of wheat straw added to soil when continuous aeration was conducted with N2‐O2 gas mixtures containing 0, 0.5, 1.0, 2.5, 5.0, and 21% oxygen at flow rates of ⅛, ¼, ½, 1, and 2 liters per hour. Rates of decomposition and total decomposition were followed by determination of wheat straw carbon evolved as CO2.
Total decomposition at all oxygen levels varied directly with aeration flow rate, except for the 0% level where an inverse relationship was observed.
Microbial activity at the 21% oxygen level was greatly stimulated as flow rate increased from ⅛ through 2 liters per hour.
A rapid increase in microbial activity occurred for the 0.5, 1.0, 2.5, and 5.0% oxygen levels as flow rate increased from ⅛ through ½ liters per hour, however, little increase in CO2 production was observed at higher flow rates.
When
Rhizobium japonicum
strain 61A68 was added to surface-sterilized soybean (
Glycine max
) seed along with 12 different coating materials, a definite effect of temperature upon survival was observed both with and without coating materials. At a storage temperature of 15°C and 50 ± 5% relative humidity, from 0.9 to 14.1% of the original inoculum survived for 3 weeks. At 22.5°C, from 0.5 to 7.2% of the original inoculum survived. At 30°C, from 0.1 to 1.6% of the original inoculum survived. The data indicated that extremely large numbers of
R. japonicum
would have to be added to the seed to have numbers adequate for nodulation survive for 3 weeks of storage at ordinary temperatures.
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