"The mushroom industry continually faces new challenges, and Penn State is there to help. The work they're doing to find methods to deal with the compost odor issue is going to be very important to the viability of our industry, especially here in Southeastern Pennsylvania." Edward Leo Mushroom producer and managing partner, John C. Leo & Son, Chester County

Mushroom Production: Sweetening the Smell

Pennsylvania produces more mushrooms than any other state in the nation. The industry generates 35 percent of the nation's fresh mushrooms and 69 percent of those used in processing. More than 353 million pounds of button mushrooms are grown in Pennsylvania each year, with a cash value of nearly $255 million—the largest of any food or feed crop grown in the state. Specialty mushrooms, such as shiitake, portabella and oyster, add even more revenue. In addition, mushroom production generates an estimated $150 million in annual payroll. Pennsylvania's mushroom industry also has significance from an environmental standpoint as an important recycler of agricultural by-products. Each year, 210,000 tons of mulch hay, 115,000 tons of poultry manure, and 245,000 tons of other byproducts including straw bedding from race tracks and stables are composted at mushroom operations to make the growing medium, called substrate, for mushrooms. But mushroom growers face a number of production problems. One of increasing significance is the odors that result from composting manure and the other byproducts used to make substrate. As businesses and new homes encroach on mushroom-growing regions, complaints about these odors are increasing. To meet this challenge, growers have sought out expertise in Penn State's College of Agricultural Sciences. The industry has long provided funding for applied research and extension programs designed to find ways to address issues affecting mushroom production. By combining these funds with ongoing support from the Commonwealth of Pennsylvania and the U.S. Department of Agriculture, the College has been able to develop a five-year plan specifically to address the odor issue. At the end of the five-year period, which began in the fall of 1997, the College plans to recommend new management practices that will reduce the odors associated with composting.

Find out what "offensive" is. An important component of the program is to understand exactly what types and concentrations of odors people deem "offensive." A little mushroom compost, for example, may not be offensive, but a lot of it probably is. There are a number of established odor-sensing evaluation methods in existence. These are being studied to find a combination that provides a more holistic way to evaluate odor than currently exists. Then, guidelines of what constitutes "offensive" can be established and used in research projects that require odor assessment. This will help researchers to find odor control methods that truly meet public expectations.

Evaluate facilities. Penn State researchers and industry representatives will visit commercial mushroom production sites in the United States and abroad that are using odor-reducing methods. These visits will expose team members to a wide variety of ideas and facilities and help them to determine which methods might best meet Pennsylvania's needs and growing conditions.

Open communication. A key goal of the program is to increase the level of communication between growers and the public. Studies of both growers and their neighbors will be conducted to determine exactly what the complaints are, under what conditions they exist, and what factors contribute to them. Extension specialists will design educational programs to inform the public about how mushrooms are grown, why odors are associated with production, and what growers are doing to control the odors. The desired outcome is to increase understanding and create more give-and-take between growers and their neighbors.

Learn to better handle water runoff. Water is an essential ingredient in the composting process, but excess ultimately runs off. Growers are required to capture this runoff in "lagoons," but if the lagoons are not properly aerated, foul odors can develop. The National Resources Conservation Service (NRCS) has built several demonstration water-runoff handling sites, five of which are located at mushroom operations in Chester County. The Penn State Cooperative Extension office in Chester County, NRCS and Penn State faculty will provide educational meetings and materials to disseminate what is learned from the NRCS sites and from other agricultural enterprises that manage water runoff containing high levels of manure.

Study the substrate. Researchers will evaluate different ingredients and management techniques that can reduce the odors released during the composting process. These studies will focus on how using different materials, additives, water amounts and turning schedules can alter these odors. Researchers also will evaluate new types of covers for mushroom compost piles to find those that effectively reduce odors.

Tried and true for Pennsylvania. An important test facility will be built at Penn State to further evaluate, refine and adapt promising new techniques. In this facility, Penn State researchers will test new structural designs for composting facilities. Different ingredient combinations for compost will be evaluated to find those that produce less odor while maintaining acceptable crop yields under typical Pennsylvania growing conditions. Other new technologies and management techniques also will be thoroughly examined.