TEMPERATURE AND CHEMICAL-CHANGES DURING COMPOSTING OF BROILER LITTER

Composting broiler litter (a mixture of manure, bedding material, and wasted feed) with commonly available high-C substrates maybe a viable alternative to reduce current land disposal practices for litter. Broi ler litter with wood shavings as a bedding material and broiler litter with peanut hulls as a bedding material were composted with wheat str aw, peanut hulls, pine bark and paper mill sludge in 0.33 m(3) batch r eactors. Litters and C substrates were mixed to achieve C:N ratios of approximately 30:1. Dry weight, total N, total C, temperature, electri cal conductivity and pH were determined at regular intervals. Maximum temperatures peaked near 70 degrees C within 2.25 d after mixing peanu t hulls with litter and within 2.58 d for pine bark and Litter. Compos ts made from paper mill sludge approached 50 degrees C within 3.71 d. Wheat straw composts never exceeded 40 degrees C which could present p otential health problems associated with pathogenic microorganisms. Ma ss loss and C:N ratio gradually declined and stabilized approximately 84 d after mixing. Mass loss averaged 73 percent for wheat straw compo st, 33 percent for peanut hull composts, and 16 percent for the other mixes. Wheat straw compost C:N ratios stabilized near 14:1 and other m ixes remained above 20:1, indicating N limited conditions for complete composting. Compost pH was 5.8 after 84 d from pine bark composted wi th wood shaving litter and was significantly lower than pH from paper mill sludge compost with an average pH of 6.9 but similar to all other compost mixes (pH 6.7). Electrical conductivity ranged from 0.35 S m( -1) for paper mill sludge composted with wood shaving litter to 0.91 S m(-1) from wheat straw composted with peanut hull litter. Composting temperature varied considerably among C sources and all required at le ast 72 d of curing to stabilize the C:N ratio. Composts made from whea t straw were most effective for waste reduction but temperatures were below the 50 degrees C level generally considered necessary to kill pa thogens.