REPORT ON MUSHROOMS (September-October
George Chan - Consultant to ZERI-BAG Pilot Projects
During my recent trip to China for an Integrated Sewage Farm project for the
Hamburg Environment Institute (HUI), I spent an aggregate of 7 days to look at
Mushroom Culture, using alternative methods to what are usually practised in
other countries. I saw mushroom installations and cultures in Guangdong,
Hangzhou and Fujian.
Mushroom culture in China emphasizes the utilisation of crop residues to produce
a high-value product (price- and protein-wise), with the compost used as more
digestible and enriched feed or fertilizer. Not only are all the crop and
processing residues (rice & wheat straw, rice & wheat bran, cottonseed meal,
corncob, bagasse, molasses, sawdust, etc.) and even newspapers utilized, but
more than a dozen varieties of special JUN grass are now planted for this
purpose because they can replace the sawdust and rice or wheat bran which can
then be used for other purposes.
The biggest breakthrough, which distinguishes the Chinese technologies from the
rest of the world, is the culture of button mushroom (Agaricus bisporus) which
usually requires big investment in costly buildings with controlled environment,
and complex processes. In China, the farmers do it in bamboo & mud buildings,
without artificial ventilation or lighting in a variety of substrates which
require NO external input. Some potash and phosphate, used in the past, are now
being replaced with digester sludge. Experiments are being carried out with
digester effluent for the same purpose; and with brewery and distillery solid
wastes to replace the soil used for the casing so that the residual compost can
be used as livestock feed, presently inadequate on integrated farms, rather than
fertilizer which is in abundance.
Mushroom is grown by individual or extended family farms in the suburbs in brick
& tile buildings covering 200-400m2. The spawns are bought in bottles from a
government station, and the strains are chosen for their high yield and disease
resistance. There is a shortage of rice straw in the province, so it is mixed
with the more available sawdust, cottonseed meal and newspaper. The mixture is
sterilized by steaming, which is labour-intensive. Rice bran, sugar, manure
(when available) and/or some agrochemicals are added to enrich the substrate
which is then put in plastic bags with each end gathered together in a special
ring to leave an area of 3cm diameter open. The spawns are put in these
openings where the mushrooms grow. The plastic bags are stacked in 5-6 layers,
one perpendicular to the other, but usually reduced to three which is considerd
to be more effective. Enough space is left between the stacks to allow the
workers to walk. The mushrooms grown are usually 2-3 kinds of oyster (Pleurotus
spp) in the cold season and straw (Volvariella volvaceae) when it is warmer.
Sometimes shitake (Lentinus edodes) is also grown, depending on the spawns being
The farm I visited had 400m2 of buildings, using 10,000 bags yearly with each
bag producing 1 kg of mushrooms within 30 days of fruiting, which is equivalent
to 10 Tons valued at US$8,000 -- a very good income for a family in China. The
substrate is only used once, and the compost is sold to a nearby farmer growing
In Hangzhou, Capital of Zhejiang province, where I went for HUI to look at
sewage and livestock waste treatment and nutrient recycling, and aquaponic
culture on fish ponds, I also discussed the culture of various kinds of mushroom
with the Director of the Hangzhou Research Institute of Energy & Environment.
He has been involved with mushroom culture before he became Director of the
Waste Recycling programme in towns, on farms and in agroindustries.
His biggest breakthrough is to grow button mushroom (Agaricus bisporus) on the
traditional substrate of crop residues, BUT with the digester sludge to replace
raw or composted manure and agrochemicals, and without the capital intensive and
modern infrastructure requiring controlled environment and complicated processes
of other countries. Unfortunately, I could only see the photos which I could not
copy because my automatic camera got stuck at that crucial moment!
This mushroom is usually cultured in autumn for 3 months and between winter and
spring for another 3 months. There was also not enough time for me to see the
installations because I had to visit various farm and sewage treatment plants.
I was also told that in Jiangxi, which is next to Guangdong province but inland,
shitake is grown year-round under rudimentary conditions, and their "flower"
variety is the most famous in China and as good, if not better, than the best
Japanese ones but are much much cheaper. I will certainly visit it during my
next trip to China.
Fujian is the Mushroom Province of China, with 25% of China's production and 10%
of the world's total. Half the mushrooms is button and some shitake, and the
other half is made up of straw, oyster and wood's ear. The mushroom industry
started 20 years ago with a fully equipped research institute to look for the
proper strains of disease resistant mushrooms to be grown by peasants with the
simplest methods possible. Among other things they have succeeded in finding
the right strains of buttom mushroom which can grow during 2 periods of 3 months
each per year in simple buildings made of bamboo, clay and straw, with no air
conditioning, heating or lighting. As mentioned above, they use the strains to
suit the climatic conditions, and grow them on 5 to 6 shelves in a high
building. They are grown on the shelves with 20cm of compost made of 2 parts
rice straw and 1 part cow manure, mixed with some potash and phosphate and
covered with a casing of soil, to produce 1 part mushroom. The growing seasons
are October-December and March-May, with the harvesting period of 45 days every
time. The residual compost can only be used as fertilizer because it is
difficult to separate the soil from the rest.
The oyster mushrooms have many varieties, producing the same quantity as the
buttom mushroom: 30-40% of the weight of the substrate, but there are 3 of them
which produce 200-300%, with the best one being Pleurotus ostreatus. They are
produced in plastic bag too, but somewhat different from that used in Guangdong.
The spawns are mixed with the substrate, and the ends of the plastic bag are
tied up completely, making the work much easier than with the rings. When the
fruiting starts, the young plants pierce the plastic, and the ends are then cut
off. Sometimes, even other parts of the plastic are pierced, but the mushrooms
are just left to grow.
The button mushroom farm I visited is in Zuqi town, Minhou county, and the
growing area is 7,000m2, producing 70 tons half-yearly which are sold to a local
cannery. This farm can grow other kinds of mushroom during the other 6 months
but prefer to concentrate on the button ones, and leave its personnel to do
other things during that period. Fujian has 50 canneries in all to deal with
the whole production of button mushrooms and asparagus in the
The smaller farms grow mushrooms during the whole year, and the total area for
the province is 300,000m2. Some of them are growing special JUN grass for use
as substrate as more farmers are shifting from rice to other crops for higher
income per unit surface, particularly on the increasing number of integrated
farms. It is claimed that the JUN grass ia a richer substrate, so the quantity
can be reduced, and the mushrooms grown on it are more nutritious.
I would like to suggest the following modifications to the Chinese institutions,
and I would certainly try them in the ZERI pilot
1. Have the plastic bags, used for oyster mushrooms, on shelves made of
bamboo to increase the growing areas instead of stacking them on the
2. Have a system of stands made with bamboo on the shelves to allow the
mushroom to grow on a larger area on every bag.
3. Put the cow manure in a digester instead of leaving it to dry in open
air, losing some ammonia, before mixing it with the straw. Then use the
digester sludge and effluent to treat the straw as shown below.
4. Let the straw soak in the digester effluent for a few days and leave it
to ferment for a while before using it for mushroom culture.
5. Mix the straw in 4 (above) with the digester sludge instead of
purchasing chemical potash and phosphate.
6. Replace the soil used for casing with solid wastes from breweries and
distilleries, containing valuable spent grains, so that the residual compost
can be used as high-value livestock feeds.
There is no doubt that mushroom culture can be a very important process of the
ZERI-BAG concept, especially NOW that we know it can all be done without the
constraints which have been put forward by many of our experts.
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