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Agroecology Ecological understanding of farming systems

Ben-Gurion University of the Negev

Prof. Bertrand Boeken The Wyler Dept. of Dryland Agriculture Jacob Blaustein Institute for Desert Research Ben-Gurion University of the Negev Sede Boqer Campus 84990 Israel Office 08-659 6893 Mobile 052-3847603

1. Introduction • Definitions

• Contexts

• Perspectives

• History of agriculture

bboeken@bgu.ac.ilhttp://www.bgu.ac.il/desert_agriculture/Agroecology/© BBoeken 2005-18

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Agroecology - definitions

Gliessman 2000: “The application of ecological

concepts and principles to the design and management of sustainable farming systems”

Understanding (Science)

Practice (Technology)

Object

Goal and Motivation Limited to a subset of farming systems (i.e., not the unsustainable ones) What is sustainability?

How does sustainability vary?

What makes a farming system sustainable?

Is sustainability always attainable?

→ Agroecology as agricultural practice

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Agroecology - definitions B. Boeken, this course: The application of ecological concepts

and principles to farming systems

All agro-systems Ecological processes associated with farming

•  Trophic structure

•  Flows of energy and materials (water, nutrients, carbon)

•  Landscape and scale

•  Population dynamics of organisms

•  Natural selection and co-evolution

•  Biodiversity of biotic communities

•  Conventional, traditional and alternative agriculture

•  Crop and animal production

•  Development through time

Understanding (Science)

→ Agroecology as a scientific discipline Wezel A. et al. 2009. Agron. Sustain. Dev. 29 (2009)

503–515 (www.agronomy-journal.org) Bensin B.M.1930. Int. Rev. Agr. Mo. Bull. Agr. Sci.

Pract. (Rome) 21, 277–284.

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Agroecosystems - context

Human activities for food production •  Hunting •  Gathering •  Fishing •  Grazing •  Farming •  Bio-industry

Human land-use •  Cropland •  Rangeland •  Woodland •  Urban/industrial •  Nature

Material human requirements •  Water, air •  Food •  Fiber •  Fodder •  Fuel •  Shelter •  Space •  Goods

www.worldfuturefund.org

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www.worldfuturefund.org

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Agroecosystems: perspectives

•  Social

•  Ecological

•  Biological

•  Technical

•  Historical http://www.worldisround.com

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Social perspectives

•  Sociology •  Economy •  Politics •  Culture •  Religion •  Heritage •  Education

www.whitehouse.gov

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Ecological perspectives •  Energy and resource flows •  Trophic structure •  Biodiversity •  Population dynamics •  Natural selection •  Animal behaviour •  Landscape dynamics •  Spatial relationships:

Relationships with surrounding ecosystems

•  Resource flows from outside •  Predators, pests and weed invasion •  Export of plant and animal products •  Leakage of water, nutrients, agro-chemicals

Processes within agro-ecosystems •  Energy, resource flows •  Crop plant performance •  Biotic community dynamics •  Soil processes

Natural ecosystems

Agro-ecosystems

Relationships between agro-ecosystems and the ‘rest of the world’

•  Resource subsidies •  Introduction of invasive species •  Export of plant and animal products •  Pollution •  Global climate change

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Biological perspectives

•  Physiology and biochemistry •  Genetics, genomics •  Phytopathology •  Soil microbiology

www.soils.agri.umn.edu

www.ncgbc.org

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Technical perspectives •  Irrigation •  Soil preparation •  Planting and sowing

www.opico.com

www.rec.udel.edu

•  Fertilizer application •  Pest control •  Harvesting

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Historical perspectives

Increasing trends •  Global and local human population size •  Control over food production

•  Dependence on technology, transport

Time-line (yrs) Archaic Homo sapiens -250,000 hunting-gathering, nomadic

Prehistoric -15,000 domesticated plants and grazers

Ancient -5,000 soil cultivation, irrigation

Medieval -1,500 deep plowing, manure, selection, profit

Modern -200 scientific approach

Contemporary -60 industrialization, alternative approaches, ecological sustainability (?)

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Early human foraging

250,000 years ago •  Nomadic hunter-gatherers

•  Small communities in open landscapes

•  Human evolution and early cultural development

http://www.archaeologyinfo.com/homosapiens.htm

Social structure: clan/family groups Food: grains, nuts, berries, tubers, vertebrates, insects Problems: predators, resource depletion, adverse selection, rival clans Innovations: clothing, domestication of dogs

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Adverse selection Gathering of wild cereal grain

•  Normal retention frequency distribution

•  People collect seeds remaining on the plants •  Moves population mean to genotypes with

lower retention

•  In short time local populations become costlier to collect

Seed retention

Freq

uenc

y

Seed retention

Freq

uenc

y

Harvested

www.flickr.com

Assumptions •  Essential or important food source •  Abundant population •  No overharvesting by reducing

abundance (no seed limitation of recruitment)

Consequences (Based on optimal foraging decisions by humans) •  Diversity of food sources (“prey switching”) •  Migration (nomadism)

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Prehistoric agriculture

www.sanford-artedventures.com

Social structure: larger clan/family groups Food: wild animals and plants, local produce Problems: predators, resource depletion, rival clans Innovations: tools, domestication of grains, herbivores

Started 15,000 years ago •  Small semi-sedentary

communities

•  Stone tools

•  Early agriculture

•  Early art

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Domestication Cultivation of cereal grain

•  Wild populations have normal retention frequency distribution

•  Planting of grains remaining in ears •  Crop population mean with higher retention

•  Crop populations become more profitable to collect www.geog.ucsb.edu

Seed retention Fr

eque

ncy

Consequences •  More control over food supply and quality •  Larger, sedentary human populations •  Reliance on resources, technology and knowledge •  Danger of resource depletion (and over-harvesting in non-seed crops)

Seed retention

Freq

uenc

y

Harvested

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Ancient agriculture

Started 5,000 years ago •  Larger villages, cities

•  Large-scale agriculture

•  Metal tools

•  Soil cultivation, irrigation

•  Food storage

•  Burocracy www.touregypt.net

Social structure: large non-family groups Food: local produce, storage Problems: predators, resource depletion, rival clans Innovations: domestication of vegetables, fruit trees, cats

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Medieval agriculture

http://medieval.ucdavis.edu

Started 1,500 years ago •  Feudal relations

•  Large cities, manors

•  Large-scale agriculture

•  Sustenance and profit

•  Plowing, fertilization

Social structure: feudal (serfdom) Food: local produce, storage, import Problems: food shortage, desease Innovations: selection, work

differentiation

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Modern agriculture

www.stolaf.edu

Started 200 years ago •  Population increase

•  Land development

•  Production maximization

•  Mechanization

•  Profit

Social structure: family business Food: local produce, storage, import, industrial processing Problems: pests, pollution, subsidies, capital investment, scale enlargement, uniformity Innovations: science-based, hybrid crops

Crop trait selection

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http://www.doctortee.com/

Genotype-environment interactions (G×E)

•  Reaction norms for 2 phenotypic traits (a,b)

•  Trade-off between the traits (c) •  Physical/physiological trade-offs:

Limitation of selection (d)

Selection for desired phenotypic traits •  Crop diversity •  Market value •  Genotypes adapted to different

conditions (temperature, resource availability, seasonality, etc.)

Soil moisture

Gro

wth

Gen

otyp

es

Wet Dry

(d)

A

B

1 2

A

B

Environment

Trai

t 1

Trai

t 2

Trai

t 2

1 2 Environment

A

B

Trait 1

A

B

(a) (b) (c)

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Contemporary agriculture Started ca. 60 years ago •  Population increase

•  Reduced natural area

•  Production maximization

•  Globalization

•  Profit, monopoly

Social structure: private and corporate business Food: import/export, industrial processing Problems: pests, pollution, subsidies, capital investment,

encroachment on nature, global warming Innovations: bio-industry, precision agriculture, genetic engineering,

alternative life-styles

encarta.msn.com