Improving Efficiency And Environmental Impact Of The Mushroom Composting Process.
Pulsed Fluorescence Sulphide Analyser
The mushroom composting industries in Ireland and Britain are facing similar challenges - increasing competition from countries where production costs are lower and continuous pressure to reduce odours created during the composting process.
Improving the overall efficiency of compost production and in particular reducing the time in expensive spawn-running facilities by increasing the rate at which compost is colonised by mushroom mycelium would result in substantial cost savings.
To achieve this, a group of commercial partners from Ireland and Britain are collaborating with scientists from the Department of Agriculture and Rural Development for N.Ireland, Horticulture Research International, Warwick and commercial research companies in the HortLINK project (HL0163) - Improving the efficiency and environmental impact of mushroom composting.
Research Aims The project aims to reduce compost processing time and improve consistency in compost quality by:
Identifying the physical and chemical properties of straw that relate to degradability in composting and subsequent mushroom growth and cropping
Identifying the factors in the substrate that influence spawn-running time. The project also aims to reduce offensive composting odours by:
Analysing the chemical and microbial properties of recycled water that result in odours and improving the treatment and application of recycled water during the composting process.
Significant Findings Variation in the rate of breakdown during composting between different types of wheat straw (cultivars, growth regulator application, site) have been detected. Further work will determine whether these differences are related to mechanical and chemical properties of the straw, and to the mycelial growth and cropping of the mushroom.
During spawn running, the mushroom mycelium produces an enzyme, laccase, which enables it to utilise the compost. By measuring the quantity of laccase, the amount of mushroom mycelium and therefore the extent of the spawn-run can be determined. A method based on an oxygen electrode has been developed for measuring the amount of laccase in compost extracts. The method is now being used to determine:
which factors affect the time taken for mycelial colonisation
whether the quality of the spawn-run of a compost is related to its mushroom cropping potential.
The Redox potential of recycled goody water can be used to indicate the oxygen demand. Water samples with a low Redox potential produced more volatile sulphides and were more odorous than samples with a less negative Redox potential. There was a wide range in the Redox potentials of recycled water from different commercial composting sites. The most effective methods of water treatment to increase the Redox potential to avoid anaerobic odours are now being identified.
Anticipated benefits for industry The results of the small-scale trials will be brought together in experiments on mushroom composting sites and farms so that the information gathered can be tested under commercial conditions.
Just a 3% increase in compost productivity due to better use of straw and recycled water would produce a benefit of �10m annually. Add to this savings from reduced spawn running time and the project is worth GBP10.5m a year to the mushroom industry.
There is the additional benefit of reducing the environmental pressure on mushroom composters and growers as a result of lower odour emissions from composting.
According to the project co-ordinator Martyn Dewhurst of Tunnel Tech Ltd "Increased efficiency of composting is a key way growers could improve their competitiveness".
Project partners The participating partners in this DEFRA and DARDNI sponsored project are: Agricultural Supply Co Ltd, Carbury Mushrooms Ltd, Casella Eti, Custom Compost Ltd, Drinkwater's Mushrooms Ltd, J.A Gooding Ltd, Greenhill Compost Ltd, Horticultural Development Council, Institute of Grassland and Environmental Research, Jeol (UK) Ltd, Monaghan Mushrooms Ltd, Mushroom Growers' Association, NIHPBS Loughgall, J Rothwell & Son Ltd, Shackleford Mushrooms Ltd, Tandragee Compost Ltd, Triton Technology Ltd, Tunnel Tech Ltd, Warwick HRI.
For further information contact:
Mairead Kilpatrick DARDNI N. Ireland Horticulture & Plant Breeding Station Loughgall, Co Armagh. BT60 8JB