Comparison of composting process and quality between rubbed bamboo and sawdust used as bedding materials for Japanese black heifers

Abstract

To evaluate their composting characteristics, rubbed bamboo powder and sawdust, used as Japanese Black heifer bedding for 3 months, were tested. Both materials were piled to 1 m in a composting depot with concrete walls on three sides and a galvanized iron roof. During the 5-month composting period, the compost piles were turned periodically (every 2 weeks) and an equal amount of water was added to maintain adequate moisture levels. The raw bamboo powder contained significantly higher acid-detergent-soluble organic matter than the raw sawdust material. The inner temperature of both compost piles increased considerably after turning. The peak temperature (50 °C) after turning was obtained during the first 2 months of composting for both materials. Thereafter, the peak temperature lowered in the sawdust compost because of a decrease of easily decomposable organic matter. The bamboo compost maintained a significantly higher pH than the sawdust compost for the last 4 months of the composting period. The volatilization of NH3 was detected for 2 months in the sawdust compost and for 4 months in the bamboo compost after compost initiation. Inorganic nitrogen in the sawdust compost was mainly composed of NO3-N and in the bamboo compost was mainly composed of NH4-N. After composting, a germination test (radish, qing geng cai, spinach and potherb mustard) was conducted using both composts. The germination rate in the bamboo compost was significantly lower than in the sawdust compost for all vegetables. From these results, we suggest that rubbed bamboo powder needs a longer composting period than sawdust.