Journal of the Society of Agricultural Structures, Japan

Moisture content and C/N ratio become a dominant factor in stabilizing compost. Well matured compost can be obtained by the temperature in compost before curing process ranged fron 65 to 70°C or more, the moisture content of a cured compost as between 45 and 50 percent for screening of bulking agent and handling without difficulty, and the C/N ratio of it as 20 or less. In order to maintain the moisture of the fresh compost around 50 percent and C/N ratio of it as less than 30 for a higher degree of curing, it was apparently necessary to control the moisture and to measure the C/N ratio for the selection of compost bulking agents.

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The number of air changes per hour (AC/hr) in a typical calf hutch was measured under various conditions as a parameter of air purity. The sensible heat production from a calf was simulated by a model having a thin sheet heater on the surface of the model body. The measurement of air exchange was made using gas tracer method with carbon dioxide gas.
The following conclusions were made from this study:
1. The number of AC/hr under calm conditions was more than 80.
2. Effect of roof inclines, no incline and 1/8 compared to normal incline (1/24), was not significant under calm conditions.
3. Front covers having a 50×50cm opening and a 60×120cm opening, Figs. 2b and 2c, decreased the number of AC/hr drastically. Front quarter covers, 30×120cm, on the bottom, top and left, Figs. 2d, 2e and 2f, had no significant effect on air exchange.
4. With a wind velocity of 1m/sec toward the front opening the number of AC/hr was more than twice (182±26.3) that under calm conditions. With the same wind velocity toward the back wall the number of AC/hr was 61±3.0.

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