Sustainable AgricultureAdopted from a presentation given by Lewis Bivona, 2013

www.cityfarmer.info

Objectives

• Agriculture as built environment• Flaws in conventional agriculture• Characteristics of

sustainable agriculture• Examples• Advantages• Drawbacks

Green Revolution

sightedmoon.com

Current Production

•~2700 calories per person per day• Could get by on 2200 …• and feed 1.5 billion more

people•Still• ~900 million go undernourished• Hunger is major health concern• Economic incentives encourage exports• Production growth rates are dropping• Will Africa embrace green revolution?

www.bubblews.com

Fertilizers

•Macro• Nitrogen, phosphorus, potassium, calcium, magnesium,

and sulfur•Micro• Boron, chlorine, copper, iron, manganese, molybdenum,

zinc and nickel•Sources• Fossil fuels – nitrogen fertilizers• Need to switch to renewable sources

•Mineral deposits• Organic material – animal waste, compost, bones

(phosphorous)

Pesticides

•Problems began environmentalist movement•3 million cases of acute

poisoning•Affect other species, reduce

biodiversity•Disrupt natural ecology

Monocropping•All crops are removed at once• Erosion during non-growing season

• Loss of diversity•Can result in increased pest action

Source: Blogs.discovermagazine.com

Genetically Modified Plants

•Banned in Europe•Embraced in US

•Some plants engineered to withstand pesticides (www.globalresearch.ca)• Allows more pesticide application• Pesticides increasing in food & water?• Health effects of pesticides, especially “Roundup”

www.stuartwilde.com

Sustainable Agriculture

•Takes advantage of relationships between organisms and their environment (ECOLOGY!)• Uses Renewable Energy• Conserves Energy• Recycles and reuses materials•Minimizes Waste•Maximizes Biodiversity•Models Natural Ecosystems

Examples of Sustainable Agriculture•Agroforestry•Hugelkultur•Permaculture•Soil Health

Management•Community Supported

Agriculture•Urban Gardening

•Crop Rotation• Intercropping•Conservation Tilling•Composting•Animal Integration•Organic farming• Integrated Farming

Advantages: Synergy•Agroforestry •Trees break the wind•Wind breaks & root structure reduce erosion• Legume trees fix nitrogen•Fruit is fodder for animals & humans or compost•Shade for farmers

www.siani.se

Hugelkultur Raised garden beds filled with rotten wood

www.permaculture.co.uk

Permaculture

•Self-maintaining agricultural systems based on natural ecosystems

pickardsmountain.org

Advantages: Biodiversity

•UN Convention on Biodiversity Definition• “the variability among living organisms from all sources,

including, 'inter alia', terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems"

•Sustainable Agriculture•On average biodiversity increases greatly• Can serve as nature corridors

Soil Health Management•Embraced by USDA Natural Resources Conservation

Service•Manage More by Disturbing Soil Less• Preserve natural soil microbes

• Diversify Soil Biota with Plant Diversity• Different plants release different carbohydrates, supporting wider range

of microbes• Keep a Living Root Growing Throughout the Year• Rhizosphere most active part of soil ecosystem

• Keep the Soil Covered as Much as Possible• Conserve moisture• Reduce temperature• Intercept raindrops (reduce destructive impact)• Suppress weed growth• Provide habitat

www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/mgnt/

Advantages: Ethical

•Small farmers see greater revenue•Kinder to animals •More likely to

preserve heirlooms•Greater focus on local

economy

www.jennyforlondon.org

Local Marketing

•Shortens supply chains•Money goes directly

to farmers•Builds relationships

between consumers and farmers•Energy efficiency

Commons.wikimedia.com

Community Supported Agriculture•Consumers

buy shares•Consumers

share risk with farmers

•Muth Family Farm

www.earthpartners.net

www.muthfamilyfarm.com

Urban Gardening

•Families support themselves•Use

underutilized space•Opportunities

for impoverished

assets.inhabitat.com

environment.nationalgeographic.com

3.bp.blogspot.com

Crop Rotation

•Minimize pests between seasons•Restore depleted

soil nutrients•Rest exhausted soil

3.bp.blogspot.com

Intercropping• Cooperative organisms planted together• Yields more food total•Mechanisms

• Chemical Repellent - plant odors confuse/repel pests• Parasitic Wasp Host Plant - provides food/shelter for

parasitic wasps that eat pests• Physical Interference – plant is physical barrier to

pest or creates life cycle interference• Predator Increase - plant acts as food source or

breeding ground for beneficial insects• Trap Crop - encourages pests to congregate; makes it

easier for beneficial insects to prey and for handpicking• Visual Masking - plants provide visual mask that

confuses the pest

www.organicgardeninfo.com/intercropping.html

permaculturesendaverde.blogspot.com

Land Equivalency Ratio

•Metric of Intercropping Benefit•Multiple of Yield/Area

•Example• Corn monoculture yields 35,000 MJ/hectare• Lettuce monoculture yields 10,000 MJ/ha• If two are intercropped:• corn yields 32,000 MJ/ha• lettuce yields 7,000 MJ/ha

• Determine land equivalency ratio of corn, lettuce, separate and combined

Land Equivalency Ratio Example cont.• LER = Ax/Mx, where• Ax = intercropping yield of crop x • Mx = monoculture yield of x

• LER of corn: Ax = 32,000 MJ/ha, Mx = 35,000 MJ/ha•

• LER of lettuce: Ax = 7,000 MJ/ha, Mx = 10,000 MJ/ha•

• Total LER = LER1 + LER2 + … + LERn

• Total LER = LERcorn + LERlettuce = •

Conservation Tilling• Leave 30% crop residue on soil surface• Less water runoff &

wind erosion•More carbon preserved • greenhouse gasses

•No Till• Plant residue left to decay• Try to avoid compaction • Freeze-thaw can help

•Strip Till• Thin strips cultivated• Just where seeds are planted

farmlandforecast.colvin-co.com

Composting•Sources• Animal &

vegetable waste• Important part

of organic agriculture•Almost entirely

replaces fertilizer

Animal Integration•Synergy from combining animals/crops• “Pig Tractors” plow

fields• Poultry clear orchids

and fertilize• Cattle clear cover

crops & provide manure compost

www.fao.org

Advantages: Energy Efficiency

•Organic farms emit fewer Greenhouse Gases•Organic farms

consume less energy

ecolocalizer.com

Organic Farming

• Combines many sustainable agriculture practices• Crop rotation• Compost• Biological pest control• Natural fertilizers & Pesticides• No GMOs• No antibiotics used in animals

http://www.scienceclarified.com/

Disadvantages - Yield?

• Recent research suggests that yield can be as high as conventional agriculture (www.misa.umn.edu)

www.un.org

Disadvantages - Land Use?

• If yields are similar, no difference with convention agriculture

Disadvantages - Labor Intensive

• Difficult work• Rise of robots may require

return to agriculture

cronkitenews.asu.edu

Integrated Farming (The Third Way)