Mitigating Global Warming Through Alternative Disposal of Used Mushroom Substrates Case Study Session Prof Etela Ibisime, RCE Port Harcourt 9th African Regional RCE Meeting 5-7 August, 2019, Luyengo, Eswatini

1. Mitigating Global Warming Through Alternative
Disposal of Used Mushroom Substrates
by
I. Etela
1
, J.N. Ingweye
2
and O. Akaranta
3
(RCE Port Harcourt)
www.rceportharcourt.org; info@rceportharcourt.org
Participating Organisations:
1
Institute of Agricultural Research and Development, University of Port Harcourt, Nigeria
ibisime.etela@uniport.edu.ng
2
Foundation for Agric and Social Transformation, Port Harcourt, Nigeria
jiningweye@gmail.com, info@fastng.org
3
Science Institute, University of Port Harcourt, Nigeria
onyewuchi.akaranta@uniport.edu.ng
Paper presented at the 9th African RCE Meeting on “Accelerating Progress Towards the Achievement
of Sustainable Development Goals in Africa” held at Luyengo, Estiwani from 5th-7th August 2019

2. Presentation Outline
• Overview of RCE Port Harcourt
• Introduction
• Project Goal and Objectives
• Project Area and People
• Conceptual Framework
• Methodology
• Results
• Major Findings
• Key Next Steps
• Acknowledgements
∼ ∼2

3. RCE Port Harcourt
(3 Core Projects)
Ecosystem Conservation
and Restoration for
Sustainable
Poverty
Reduction and
Human Capital
Development
Green Science Education
- Science on Wheels
Flagship Project
• Economic empowerment
(capacity building / skills
transfer)
• Waste-to-wealth
• Bioremediation of degraded
environment due to mineral
exploration & exploitation (solid &
liquid minerals)
• Greening environment for mitigating
climate change
• Capacity building of science
teachers (train-the-trainers)
• Encourage science teaching &
learning at primary & secondary
schools
∼ ∼3

4. Introduction
• Increased awareness about the nutritional value of mushroom is
leading to more production and consumption in Nigeria
• Different agricultural wastes used as substrates for cultivating
mushrooms in Nigeria
• Resulting to large tons of spent mushroom substrates produced
• Spent substrates either left unused leading to greenhouse gas
emission during decay or partly as mulch for cropping
• Project focused on converting spent mushroom substrates to
farm animal feed (Belewu & Belewu, 2005; Kinfemi et al., 2009;
Etela et al., 2018)
∼ ∼4

5. Photos of a complete mushroom (a) and spent mushroom substrates (b-e)
Plate bPlate a
Plate c Plate d Plate e
∼ ∼5

6. Project Goal and Objectives
Goal
To reduce greenhouse gas emissions and mitigate global warming
Objectives
• To determine chemical composition of used substrates from three
mushroom species
• To estimate methane gas production from the used mushroom
substates from three species
• To evaluate in vitro dry matter digestibility of three mushroom
species grown on sawdust
∼ ∼6

7. Project Area and People
• Choba Community in Niger Delta, south-south geopolitical zone of Nigeria
• Oil and gas hub in Nigeria and the Gulf of Guinea
• Inhabitants fisherfolks and farmers livelihoods threatened by non-farm
businesses (social; economic; environmental)
• Motivated to make agriculture more responsive to global 17 SDGs
∼ ∼7

8. Conceptual Framework
• Edible mushrooms are fungus capable of degrading cell
wall making them more digestible (Pleurotus tuber-regium;
Pleurotus ostreatus; Volvariella volvacea)
• Animal welfare: conscious of the 3Rs (Reduction;
Refinement; Replacement)
• Duration: March 2014-October 2018
• Spent mushroom substrates obtained from Mushroom
Unit, Demonstration Farm, University of Port Harcourt
and Bazaleel Mushroom Farm, Rivers State
∼ ∼8

9. Methodology
• Samples from three spent mushroom substrates (SMS)
dried 60ºC for 72 hours
• Chemical composition determined on the three SMS
(AOAC, 2002)
• In vitro gas production technique was used (Menke and
Steingass, 1988)
• Estimated total and methane gas production, and dry
matter digestibility
• Data obtained were analysed using statistical software
(SAS, 2002).
• Results presented in tables and charts
∼ ∼9

10. Table 1. Chemical composition (g/100g DM) of spent sawdust
and cotton substrates from three mushroom species
Results
Spent Mushroom Substrate Dry matter
Organic
matter
Crude
protein
Neutral
detergent
fibre
Pleurotus tuber-regium on sawdust 70.6c
98.2b
14.9a
67.0b
Pleurotus oestratus on sawdust 74.4b
96.8a
5.3b
84.5a
Volvariella volvacea on cotton waste 87.4a
97.3ab
88.8b
84.3a
Mean 77.5 97.4 9.6 78.6
s.e (df = 3) 0.98 0.31 2.65 8.50
∼ ∼10

11. Table 2. Gas production rate and in vitro dry matter (DM) digestibility
of spent sawdust and cotton substrates from three mushroom species
Results (cont’d)
Spent Mushroom Substrate
Gas production
(L/h/ton)
In vitro DM Digestibility
(g/100 gDM)
Pleurotus tuber-regium on sawdust 0.48 90.1
Pleurotus oestratus on sawdust 0.27 96.5
Volvariella volvacea on cotton waste 0.87 97.3
Mean ± s.e (df = 3) 0.55 ± 0.110 90.0 ± 12.93
∼ ∼11

12. Figure 1. In vitro gas production ((mL/200mg)) by spent sawdust
and cotton waste substrates from three mushroom species
0.0
3.0
6.0
9.0
3 h 6 h 9 h 12 h 15 h 18 h 21 h 24 h
Pleurotus tuber-regium on sawdust
Volvariella volvacea on cotton waste
Pleurotus oestratus on sawdust
Results (cont’d)
∼ ∼12

13. Figure 2. Methane gas output (mL/200mg) by spent sawdust
and cotton substrates from three mushroom species
Results (cont’d)
0.0
3.0
6.0
9.0
Pleurotus tuber-regium on sawdust Pleurotus oestratus on sawdust Volvariella volvacea on cotton waste
6.5
2.0
3.0
∼ ∼13

14. Major Findings
• Edible mushrooms are fungus capable of degrading cell
wall making them more digestible as animal feed
• Spent mushroom substrates could be converted to
beneficial products like meat without causing
environmental nuisance when left to open-air decay
• Mushroom species differ in level of fibre utilisation and
methane (greenhouse) gas emission
• Pleurotus ostreatus species on sawdust appear most
suitable for use to minimise methane emission
• Contributes to SDG 13 (Climate Change) and SDG 15 (Life
on Land)
∼ ∼14

15. Next Key Steps
• Conduct on-farm studies using action research with
farmers as key researchers
• Working with farmers to identify locally used plants
with anti-methanogenic properties as feed supplements
• Promote use of Pleurotus ostreatus mushroom species
cultivated on sawdust in the project area
• Reached out to about 100 direct target farmers
• Enlighten about 15,000 indirect target beneficiaries via
formal (published) and non-formal channels (person-to-
person contacts)
∼ ∼15

16. Acknowledgements
The authors, sincerely, appreciate the:
• United Nations University - Institute for the
Advanced Study of Sustainability (UNU-IAS) for
funding the trip to attend the conference and
present the paper
• The Local Organising Committee, RCE Eswatini,
Kingdom of Eswatini for accepting the paper for
presentation at the 9th African RCE Meeting
∼ ∼16

17. Thank you, for listening
∼ ∼17