Presented at Third Summit of Science Academies of South Asia and General
Assembly of Association of Academies and Societies of Sciences in Asia, 14-17
October 2014, New Delhi, India
Are we wrong in conventional
approach of agriculture?
Gamini Seneviratne
Research Professor
Microbial Biotechnology Unit (MBU)
Institute of Fundamental Studies (IFS)
Kandy
Sri Lanka
E-mail: gaminis@ifs.ac.lk
Introduction
• How does an ecosystem work?
- Ecosystem is a food web-based
network of interactions of organisms &
the environment
- Nutrients are conserved in
undisturbed ecosystems, leading to
sustainability, particularly due to their
cycling in the producers-consumersdecomposers loops
Producers-consumers-decomposers
loops
Food web-based network of
interactions of a forest ecosystem in
USA, using Pyrosequencing
http://jarrettbyrnes.info/networks.shtml
Flora & fauna
Microbes
In the food web-based network of
interactions
• Interaction lines are synergistic
(positive) or antagonistic (negative).
• As long as all the interactions are intact,
the ecosystem is equilibrated and
sustainable (Lupatini et al. (2014)
Frontiers in Environmental Science
(www.frontiersin.org)
In food web-based network of
interactions of forest ecosystems
• Some microbes and fauna (particularly insects)
contribute to structure or stratify plants, by consuming
(feeding on) seedlings of the same species growing at
high densities on the forest floor
• Thereby, they thin the seedlings, thus allowing the
other species too to emerge, leading to remarkable
diversity (Bagchi et al. (2014) Nature 506, 85-88).
• Thus, those microbes and insects play an extremely
important role in forest structuring and diversifying.
Remarkable diversity in forest ecosystems
In forest conversion to agriculture
• Stress factors like forest clearing, tillage and
chemical inputs reduce biodiversity of
functional flora, fauna and microbes.
• Most of the disappeared biodiversity enter
into an inactive or dormant phase to bypass
the stress factors, by forming ‘seeds’, which
are stored in soil seed bank.
Chemical inputs reduce biodiversity
of microbes
CF applied tea soil
Forest soil
In agroecosystems (i.e. forests
converted to agriculture)
• The natural food web is collapsed due to removal
of flora, fauna & suppression of microbes.
• Then, remnant forest structuring and diversifying
microbes and insects start feeding on our crops in
the absence of other plants for them to feed on.
• Then, we name them as pathogens and pests
attacking our crops. This is how pathogens and
pests originate in agroecosystems.
In agroecosystems
• The reduced biodiversity due to stress factors
leads to;
- reduced photosynthesis and carbon
accumulation due to removal of flora
- depletion of soil organic matter due to
reduced fungal diversity and fauna.
• These lead to retarded nutrient cycling, soil
moisture stress, yield decline etc., thus
collapsing sustainability of agroecosystems.
In conventional agriculture
• We address above issues by killing pests and
pathogens, by increasing chemical fertilizer
use with yield decline etc., which contribute to
further depletion of biodiversity.
• As one can understand, what we should have
done, was to reinstate the lost biodiversity for
re-establishing ecosystem functioning and
sustainability of agroecosystems.
• Thus, in this manner, we are wrong in the
conventional approach of agriculture.
With this understanding
• We developed biofilm biofertilisers (BFBFs) for
reinstating biodiversity of degraded
agroecosystems.
• Their major role after field application is to
increase soil biodiversity through breaking
dormancy of the soil seed bank that was
developed under the stress conditions.
• This increase of the biodiversity leads to improve
ecosystem functioning, which in turn reinstates
sustainability of degraded agroecosystems.
• In addition, the BFBFs application increases
endophytic colonization of microbes, which helps
improve environmental stress tolerance of plants.
BFBFs
Fungal-bacterial biofilm (FBB)
Seneviratne et al. (2008) World J.
Microbiol. Biotechnol. 24:739–743
- A method to direct
application of developed
microbial communities in
vitro, to the soil
- Beneficial communities of
microorganisms (bacteria,
fungi & cyanobacteria) in
surface-attached biofilm
mode
- Different from organic
fertilizers and conventional
biofertilizers
- More effective than
conventional biofertilizers
Some highlights of BFBFs
application in different crops &
other benefits
Effects of BFBFs on tea
In collaboration with TRI
Tea nursery at Ratnapura
Young tea field trial at Ratnapura
Causalities due to drought
BFBFs + 50% CF
100% CF
Biocontrol of pathogens by stimulating emergence of
microbes from soil microbial seed bank by BFBFs (no Fus. or Trich.)
Maize-BFBFs large-scale trials at MahiyanganaPlenty Foods (Pvt.) Ltd (30% yield increase over
100% recommended CF)
BFBF + 50% rec. CF
100% rec. CF
BFBFs for Potato
BFBFs for Anthurium
BFBF + 50% CF vs 50% CF
A 250 ml bottle of Biofilm biofertiliser for tea “Biofilm-T”.
Two of these bottles with 50% of recommended chemical
fertilizers are adequate for 1 acre of tea cultivation
A luxuriant growth of tea cultivation with Biofilm-T
application in the south of Sri Lanka (10-80% yield increase
depending on soil & climatic conditions)
Comparison of tea buds of crops treated with Biofilm-T +
50% of chemical fertilizers (left) and 100% of chemical
fertilizers alone (right)
Other crops studied
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Rubber – RRI
Coconut- KPL
Sugar cane- SRI
Strawberry- ARS, Seetha Eliya & Growers
Vegetables- SARD
Tree nurseries- OUSL, Popham Arboretum, Dambulla
Investigators & collaborators
• IFS- Prof. S.A. Kulasooriya, L. Herath, S. Ekanayake, U.V.A.
Buddhika & N. Weeraratne. Tec. Assist.- K. Karunaratne, A.
Pathirana, Kosala Kumara, Volunteers………………..
• TRI- A. Jayasekara & L. De Silva
• RRDI- S.N. Jayawardana & A. Subasinghe
• RRI- R. Hettiarachchi & S. Dharmakeerthi
• Plenty Foods (Pvt.) Ltd. & Univ. of Peradeniya – A.
Gunaratne, Preethi Viraj, M. Ariyaratne, H. Ariyawansa & K.
Manikdiwela
• NBG- C. Seneviratne
• SARD- L. Weerakoon, A. Indrajith
• Uva Wellassa Univ.- A. Priyashantha, D. Sinhalage
• Univ. of Colombo- S. Thirimanne, T. Perera
• Universities & Research Institutes……………..