Managing Spent Mushroom Compost

Abstract

This project addressed how to manage spent mushroom compost (SMC), an issue of critical importance to the continued development of the Irish mushroom industry. The most important aim of the project was to devise a feasible strategy for the management of this material on an industry wide basis. There were two main components of the project, which were conducted in parallel. One analysed the structure of the mushroom industry and the logistics of handling, transporting and processing SMC. The other studied the agronomic properties of SMC in an effort to develop improved guidelines on the best use of SMC in crop production. Our analysis of the SMC management problem led us to conclude that a centralised approach should be taken when developing the solution strategy. The model solution that was formulated is based on the establishment of centrally located depots for SMC collection, temporary storage and possible processing. This approach facilitates a variety of environmentally acceptable SMC end uses ranging from land application to incineration. We examined a variety of possible end uses for SMC, including its use as an alternative fuel. In the immediate future, we believe the predominant end use for SMC will be as an organic manure for field crop production and as a soil conditioner in the landscaping industry. Uses of this type are in line with both Irish and EU legislation regarding waste management. Our analysis suggests that tillage and horticulture offer the best promise for realising the beneficial properties of SMC. We have tested SMC on field crops such as winter and spring wheat and potatoes and on glasshouse crops such as tomatoes. These experiments have shown that SMC increases soil organic matter and improves soil structure. SMC is a very effective source of K and P and also provides trace elements. It makes a contribution to N nutrition but most of the N does not become available to the crop in the first year. For best results therefore, supplementary N must be applied. Overall, our results indicate that SMC can be used with beneficial effects in field crop production. The mushroom industry should move forward with establishing centralised SMC handling facilities to enable the efficient collection, temporary storage, further processing and transportation of SMC to end users. An education and awareness campaign should be conducted amongst farmers, in areas removed from mushroom production, to introduce them to the benefits of SMC and ways to effectively utilise this material.