Reduce / Reuse / Recycle

August 22, 2005


Oyster Shells Increase Nameko Mushroom Yield by 10 %

Keywords: Environmental Technology Food Manufacturing industry Reduce / Reuse / Recycle University / Research institute 

As of March, 2005, the Ishikawa Forest Experiment Station in Ishikawa Prefecture has demonstrated that adding oyster shell to the substrate medium used in 'nameko' mushroom cultivation results in about a 10 percent increase in yields. This method is expected to kill two birds with one stone by expanding use of the enormous amounts of oyster shells discarded on the Noto Peninsula in Ishikawa, a major oyster production area in Japan, while enhancing the productivity of nameko cultivation.

In artificial mushroom cultivation, mushrooms are grown on a culture medium, usually a mixture of sawdust, wheat bran and soybean residue. Daisuke Takahashi, a former engineer at the Forest Experiment Station, focused his studies on calcium-containing materials such as hydrated lime as culture medium additives for controlling pH. Raised on the Noto Peninsula, he knew about the huge amount of wasted oyster shells, which gave him the idea of using oyster shells as a pH adjuster.

His experiments showed that a culture medium containing 3 percent oyster shell powder increased the mushroom yield by about 10 percent. Increasing the percentage of powder to 10 percent allowed the mushrooms to be harvested four days earlier, though without an increase in yield. The calcium content of nameko mushrooms also increases when oyster shell powder is used, so the mushrooms are expected to have more health value.

Mushroom production facilities and growers' associations in Kanazawa and Hakusan Cities, Ishikawa Prefecture, conducted the tests. Some companies in Hakusan have already commercialized oyster shell powder and started selling the product. Oyster shells are partially recycled as a soil conditioner, but more than 2,000 tons of them are simply discarded every year. Although it is estimated that nameko mushroom growers in the prefecture will only consume about six tons a year, the Forest Experiment Station plans to promote oyster shell recycling among shiitake mushroom growers as well, and expects that total consumption by mushroom growers could rise to 18 tons annually.

Posted: 2005/08/22 02:05:57 PM
Japanese version