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 SeneviratneResearch 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-consumers-decomposers 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- 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 Fungal-bacterial biofilm (FBB)

Seneviratne et al. (2008) World J. Microbiol. Biotechnol. 24:739–743

Some highlights of BFBFs application in different crops &

other benefits

Effects of BFBFs on teaIn collaboration with TRI

Tea nursery at Ratnapura

Young tea field trial at RatnapuraCausalities 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 Mahiyangana- Plenty Foods (Pvt.) Ltd (30% yield increase over 100% recommended CF)

BFBF + 50% rec. CF 100% rec. CF

BFBFs for Potato

BFBFs for AnthuriumBFBF + 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• 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……………..