Volume 10 Part 2 Article 6: Conservation of Materials during Composting

Volume 10 Part 2 Article 6
Year 1979
Title: Conservation of Materials during Composting
Author: J.F. Smith

Abstract:

Materials for composting are getting more expensive and this, together with increased labour and machinery costs, has encouraged a search for more economic methods of composting. As 50 percent or more of the total dry matter at stacking is lost during the two-phase system of composting, it is worthwhile developing composting methods where considerable savings of raw materials can be made while maintaining the yield of mushrooms.

Sinden and Hauser (1950) found that the greatest loss of material during Phase I of composting on the yard occurred between 7 and 15 days, and that subsequent yield of mushrooms per unit area of compost reached its maximum after 11 days of composting. They therefore suggested that a short method of composting, properly performed, would result in a more efficient use of the then dwindling horse manure supplies. Later, Sinden and Hauser (1953), developed a system of composting in which Phase I was reduced from 14 or more days to 7 days whilst Phase II , completed in a purpose-built pasteurisation room, was reduced from about 7 days to 3 days. Besides saving time, material, space and labour by this method, they were the first workers to demonstrate that the process of composting could be controlled more efficiently than hitherto and therefore made a major step forward in the art of composting. Except for minor variations, their basic procedure is followed by the majority of mushroom growers today.

Hayes and Randle (1968a) demonstrated that the addition of soluble carbohydrates in the form of molasses to horse manure composts reduced dry matter losses from about 40 to 30 percent. The increased yields obtained from these composts were associated with a conservation of dry matter and the increased microbial populations. Hayes and Randle also showed (1968b) that there was considerably more dry matter loss, up to 60 percent, in a compost made from wheat straw and chicken manure (GCRI formula 2) than in one based on straw and horse manure. Nevertheless, formula 2 composts prepared in 14-21 days were less variable and gave mushroom yields per tonne of compost at spawning comparable to those obtained from horse manure composts. Formulations employing wheat straw, chicken manure, molassed brewers grain and gypsum RÄNDLE (1973) are currently used at GCRI and yields of 180-200 kilos of mushrooms per tonne of compost at spawning are regularly obtained over a 6 week cropping period.

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