Static pile, passive aeration composting of manure slurries using peat as a bulking agent

The feasibility of composting high-moisture manure slurries in combination with hydrophilic peat moss was examined. Horticultural grade peat, with or without lime (1% Ca in peat), was mixed with manure slurries from dairy cows, poultry, or sheep, in a feed-mixer. The mixtures were discharged on to a bed of peat (10 cm), overlain by horizontal perforated pipes open to the atmosphere, to construct small windrows which were then covered by a 5-cm layer of deodorizing and hygienic peat. The amphoteric peat of acidic pH adsorbed the NH₃ and any other malodorous compounds, and its fibrosity (bulk density 0·06 g cm⁻³) supported aerobic thermophilic decomposition in which neither malodorous amines nor sulphides were produced significantly. No detectable NH₃ or H₂S emanated from the compost piles. Temperatures greater than 45°C were reached in the composts within 1–3 days and maintained above 45°C for 2–5 weeks without further mixing of the composts, or any mechanical aeration. When the composts were remixed and reheaped, 7 weeks after initial formulation, no reheating occurred—suggesting that the composts were ‘biostable’, as is peat. Germination tests confirmed the ‘biostability’. The mature composts had water-holding capacities nearly equal to that of the original peat, suggesting that the air-dried peat-manure composts can be recharged with manure slurries. The properties of the composts suggested that they could be marketed and used as a substitute or supplement for the limed and fertilized peat generally used in gardening, landscaping and greenhouse culture.