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

Different methods of composting

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.