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Compost analysis,
recycling of Spent
Mushroom Substrate (SMS)
B.L.Attri
ICAR-Directorate of Mushroom
Research
Chambaghat, Solan (H.P.)- 173 213
Compost is considered "spent" when one full crop of
mushroom, has been taken or when further extension of
cropping becomes unremunerative.
Mushroom growing is an eco-friendly activity as it utilizes
the wastes from agriculture, poultry, brewery etc. and in
turn produces mushrooms with excellent and unique
nutritional and medicinal attributes.
If not handled properly it creates various environmental
problems including ground water contamination and
nuisance.
Spent Mushroom substrate
Rationale
1.9-0.4-2.4% (N-P-K) before weathering and 1.9-0.6-1.0 (N.P.K) after weathering
for 8-16 months.
SMS contains much less heavy metals than sewerage sludge, which precludes
its classification as a hazardous substance.
SMS obtained from various sources usually have conductance in the range of
1.9 to 8.3 memos/cm.
Chloride used to be one of the major inorganic anions in SMS and it varies
from 1.5 to 7.5kg/1000 kg in fresh SMS, while 0.3kg/1000kg in well rotten SMS.
SMS has an initial pH of 7.28 which increases during weathering.
The volume of SMS also decreases (shrinkage) over the time.
The fresh SMS obtained from various sources varies in its density : 0.198
g/cm3 with a range of 0.15 to 0.24 g/cm3 in U.K., 0.475 g/cm3 in Ireland and
0.24 to 0.62 g/cm3 in USA.
Traits of spent Mushroom substrate
Industrial
waste
Agro waste Poultry waste
Organic waste
collection
Mushroom
Cultivation
Residue after
cultivation
Microbial Protein
Food
Soil health
improverFodder Bioremediation Organic
farming
Vermiculture and
Vermicomposting
Biogas Disease
control
Mushroom
cultivation
Fuel
Sludge
Soil
Excreta
Animal feed
Recycling of Spent Mushroom Substrate
It leads to an improvement in soil texture, water
holding capacity and nutrient status of soil.
It does not have any adverse effect on soil
alkalinity while, its amendment in soil leads to
an increase in the organic carbon content.
The phosphorus and potassium requirements
of the crop plants can be fulfilled by
incorporating 5% of SMS by volume, while
nitrogen requirement can be fully met by 25% of
SMS by volume.
1. Reclamation of soil
Table 1. Response of tomato seedlings (g/plant) to rate of
SMC in a peat based substrate used as a single nutrient source
SMC% by
volume
Nutrient supplied by SMC
N P K
5 6.6 22.6 18.3
10 8.2 23.1 19.2
15 10.9 24.7 20.7
20 12.0 22.0 20.0
25 13.4 21.1 19.9
30 13.6 17.3 18.6
F-test -- -- --
SE (df=54) 0.4 0.9 0.6
Table 2. Silage yield (Dry t/A and % N) from fields where
spent mushroom compost was applied annually
Treatment
t/Acre
1988b 1989 %N 1990 %N
Control 1.13 2.42 0.80 4.67 1.09
100 1.87 4.27 1.39 14.34 1.37
200 1.97 3.60 1.50 16.08 1.39
400 Nc 3.98 3.58 15.78 1.37
Nc: No harvest due to death of plants
Table 3. Corn grain yields (t/A at 15.5% H2O) from
research plots where spent mushroom was tilled
in prior to planting
Treatment
t/Acre
1988b 1989 %N 1990 %N
Control 18.8 33.1 0.80 16.7 1.09
100 21.9 66.8 1.39 268.1 1.37
200 24.1 59.1 1.50 252.5 1.39
400 Nc 74.9 1.58 300.9 1.37
Data represent average of 3 replications
Nc: No harvest due to death of plants
Suitable treatments
Rapid salt leaching
Weathering in open for two to three years
Use as manure for
Flowers
Vegetables
Fruits
Saplings
Ornamental shrubs
Horticulture plants of economic importance
Common vegetables:
Cucumber, tomato, broccoli, tulip, cauliflower, peppers, spinach
etc. but the response of the plants vary at different levels of SMS
incorporation
2. Organic manure
The actinomycetes, bacteria and fungi inhabiting the compost
exert antagonism to the normal pathogens surviving and
multiplying in the soil eco-system.
It restricts the root knot infestation of tomato plant by
Meloidogne incognita.
The extract from SMS inhibits the conidial germination of
Venturia inaequalis, causal agent of apple scab; Cochliobolus
carborum, causing disease on maize and Sphaeropsis sapinea
causing disease on red pine.
The weekly/biweekly application of spreader/sticker amended
SMS extract, starting from green tip to petal fall of apple tree
reduces the scab- affected leaf area.
3. Disease management
Mechanism
• Chemical adsorption of organic and inorganic
pollutants
• SMS harbors diverse category of microbes
Actinomycetes (Streptomyces sp. and
Thermomonospora sp.) responsible for having
strong Pentachlorophenol (PCP) catabolizing
capabilities.
4. SMS for bioremediation
• 44.4-60.5% disappearance of PCP in 21 days with spent sawdust of shiitake
mushroom, supplemented with nutrient solution of glucose, thiamine and mineral
salt.
• Faster degradation of 3 and 4 ring compounds with oyster mushroom SMS.
• Near 80-100% decolourization of different dyes with SMS of different mushrooms
under ideal cultural conditions.
• Faster degradation of different pesticides and fungicides in presences of SMS based
manure under field conditions.
• Decontamination potential of land sites used for disposal of hazardous wastes.
• Enhanced alachlor disappearance and protection from root injury in garden pea cv.
Taichung.
• An ideal choice for passive treatment of coal mine drainage.
• Use in construction of artificial wet land.
• Stabilization of abandoned mine sites, pipeline construction sites and
commercial/industrial sites.
Examples
The respawning of Agaricus spent compost together with the
addition of Spawn mate (delayed-release nutrient) and Bonaparte
peat (adsorbant material) resulted in good yield of second Agaricus
crop.
Shiitake spent mushroom compost supplemented with 10% wheat
bran and 10% millet could be utilized for Pleurotus sajor-caju
cultivation but it required air-drying, grinding, supplementation,
pasteurization and spawning steps.
P. sajor-caju cultivation on spent shiitake base medium with 12%
soyabean and 1.0% calcium carbonate with increased biological
efficiency and mushroom size.
An-aerobically fermented spent mushroom substrate as casing
material for button mushroom cultivation with additional advantage
of less bacterial blotch infection.
5. Re-growing of mushrooms
Table 4. Percentage biological efficiency (% B.E.) and
mushroom size of Pleurotus sajor-caju produced (21 days) on
spent shiitake substrate, supplemented with precipitated
calcium carbonate (CaCo3) and whole, ground soybean
Supplement rate % B.E. (%) Size (g)
Soybean CaCO3
12 1 62.4 11.6
24 2 60.2 8.7
24 0 56.3 8.7
12 2 56.0 9.5
24 1 55.9 9.4
0 2 54.3 11.1
12 0 41.8 8.0
0 1 29.3 8.4
0 0 28.2 7.8
Oyster mushroom SMS makes available the feed
with higher protein value and digestibility than
ordinary feed
The Pleurotus SMS can substitute about 30% of the
total feed without affecting the growth of animals
The protein content in P. ostreatus and Lentinula
edodes SMS increased from 24.1 to 32.3% and
28.4% to 36.7% respectively after Solid State
Fermentation (SSF)
It also increased the in vitro digestibility of total
crude protein by 70%
6. Animal feed
Table 5. Effect of pilot-scale SSF fermentation on the
contents of spent compost medium
Media with 35% spent compost of
P. ostreatus L. edodes
Control Fermented Control Fermented
Crude Protein
(%DW)
24.1 32.3 28.4 36.7
Crude Fibre (%DW) 14.8 10.2 13.3 9.8
Crude ash (%DW) 6.5 9.0 6.5 9.3
In vitro crude
protein
digestibility (%DW)
64.2 67.8 68.7 70.1
DW - dry weight
Table 6. In situ dry matter digestibility (DMD) of
untreated and Pleurotus treated paddy straw (10 days
after first flush)
Substrate DMD % increase/decrease
in digestibility
Untreated paddy straw 40.68 --
Unfermented PS
treated with P. florida
54.20 +33.23
Unfermented PS
treated with P.sajor-
caju
59.20 +45.53
Semi-fermented PS
treated with P. florida
49.57 +21.85
Semi-fermented PS
treated with P. sajor-
caju
52.72 +29.66
SMS from oyster mushroom can be utilized further as
cattle feed and the waste of cattle, i.e., manure can be
used for producing biogas and the solid residue such
obtained again can act as good casing material
Again the SMS thus generated can again be used for
raising crops
The increased susceptibility and increased nitrogen
contents of the spent residues are the main reasons
behind high % of gas yield
Solids from the digester act as very good fertilizer for
nursery raising as well as for the vegetable crops
7. Biogas production (Fuel)
Table 7. Recycling mushroom substrates and
wastes
Recycling Course Product Waste
Cultivation cotton Fibres Plant residue cotton
straw
Cultivation of oyster
mushroom on straw
Oyster mushrooms Spent substrate
(SMS)
SMS used as cattle
feed
Meat and milk Manure
Manure fermented to
produce biogas
Methane energy Residue ("Cabutz")
Cabutz used as casing
soil for champignons
Champignons SMS
SMS composted for
organic farming
Organic food crops No further waste
Major concern are:
Increase in 10 to 100 time salt concentration in soil water
Elevation in the concentration of ammonium, nitrate,
chloride, sulphate, calcium, magnesium, sodium and
potassium in the ground water
More dissolved organic carbon, dissolved organic nitrogen
and nitrate with no pesticide residue in soil and ground
water
Variation in pH (8.2-7.3), conductivity (2380-1410 memos/
cm3), carbon:nitrogen ratio (9-15:1), nitrogen availability
(organic and inorganic) and in the ratio of nitrate N to
ammonia N
Conclusion
SMS requires some early treatments like
desalting/prolonged leaching and recomposting because
the desalted or recomposted material have shown
several advantages over fresh.
The spent mushroom substrate quality parameters like
its conductivity, load of heavy metals and phosphate
should be given due consideration before using in the
field.
So in the era of growing environment awareness and
strict legislations, the exploitation of SMS for the
management of environment, agriculture and production
of recyclable energy should be encouraged.