Volume 12 Part 1 Article 50: Controlled Environment Composting in Bulk Chambers and Deep Troughs

Volume 12 Part 1 Article 50
Year 1989
Title: Controlled Environment Composting in Bulk Chambers and Deep Troughs
Authors: P. Perrin and R. Gaze

Abstract:

The preparation of mushroom compost has for many years been divided into two distinct phases: phase I, during which raw materials are mixed, wetted and stacked with considerable dry matter loss: phase II the familiar pasteurisation and conditioning treatment (s) which produces a selective and pathogen free substrate.

Phase I usually involves a prewetting/mixing phase followed by varying lengths of time spent in conventional compost stacks. During this phase fungal and bacterial activity produce large quantities of heat. Temperature ranges between ambient and 80°C in distinct zones within a cross section of the compost stack.

However, it was proved as long ago as 1941 by Lambert that the most productive areas within the then current low wide stacks were the regions of the compost within a temperature range of 45 to 55°C.

Ross and Harris (1982) found that ammonia disappeared most rapidly in the range of 40 to 45°C although disappearance was still fairly rapid over the range of 35 to 50°C. Temperatures above 50° C, however, prolonged the disappearance of ammonia. At these higher temperatures and also at 40°C and below non selective composts were produced.

Several workers have employed a form of controlled composting with material conservation in mind, e.g. Randle and Hayes (1972), Smith (1983) or as an attempt to simplify the composting process, Laborde and Delmas (1969).

The results usually gave a lower yield in terms of kilograms of mushrooms per tonne of compost filled although dry matter losses during preparation were reduced from about the 60 % expected from conventional composts to about 25 %.

Bech (1979) managed to reduce the total fermentation time by having a 2 day phase I followed by a 3 day phase II, Flegg and Randle (1980) reduced phase I and II of a GCRI formula 2 compost from 8 days to 4 days and from 10 days to 6 days without reducing the yield per tonne of prepared compost.

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