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www.cityfarmer.info
Objectives
• Agriculture as built environment• Flaws in conventional agriculture• Characteristics of
sustainable agriculture• Examples• Advantages• Drawbacks
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
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
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
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 - Labor Intensive
• Difficult work• Rise of robots may require
return to agriculture
cronkitenews.asu.edu
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