Sustainability final

Food system

• interconnected systems that influence nutrition, food, health, community, development, and agriculture

• all stages: growing, harvesting, processing, packaging, transporting, marketing, consumption, distribution, and disposal

Monoculture

• growing a single crop variety on a large area of land

• increases efficiency but depletes soil nutrients, encourages pests and weeds, increases dependance on fertilizers

Green revolution

• 20th cent to 1980s

• development of high yield crop varieties, use of chem fertilizers and pesticides, expansion of planned irrigation

Eutrophication

• excess nutrients accumulate in water, increased growth of microorganisms that deplete oxygen

• caused by fertilizer runoff, sewage, industrial wastewater

Harmful Algal Bloom (HAB)

• causes negative impacts on other organisms

• depletes oxygen, blocks sunlight, or producing toxins

Hypoxia

• depletion of dissolved oxygen

• caused by decomp of dead algae

• leads to envi degradation results in dead zone

Dead Zone

• area in water where oxygen levels are so low aquatic life cannot survive

• can be localized and seasonal (lakes) or massive and recurring (oceans)

Limiting nutrients

• nutrient in shortest supply relative to what organisms need to grow

• defined by Liebig’s Law of the Minimum

Liebig’s Law of the Minimum

• growth is limited by the scarcest essential nutrient even if all others are abundant

• phosphorus limits freshwater system; nitrogen limits marine systems

Nitrogen cycle

A biochemical cycle that circulates nitrogen between atmosphere and biosphere thru nitrogen fixation, ammonification, nitrification, assimilation, denitrification

• key supporting ecosystem service

Nitrogen fixation

• conversion of atmospheric dinitrogen into Ammonia by nitrogen fixing bacteria

• entry point for atmospheric nitrogen into biosphere

Ammonification

• decomp of dead organisms and waste into ammonia by bacteria

• also called mineralization

Nitrification

• conversion of ammonia into nitrates by nitrifying bacteria

• nitrates are the primary form of nitrogen absorbed by plants

Assimilation

• process which absorbs nitrates and ammonia from soil to incorporate them into bio molecules like proteins and nucleic acids

denitrification

• conversion of nitrates back into dinitrogen gas by dinitrifying bacteria returning nitrogen to the atmosphere and completing the cycle

Dinitrogen

• the inorganic unusbale form of nitrogen that makes up 80% of Earths atmosphere

• must be converted into ammonia or nitrates before it can be used by most living organisms

Haber Bosch process

• industrial chemical process that converts atmospheric dinitrogen and hydrogen into ammonia.

• 1909

• consumes 3-5% of the worlds natural gas and is responsible for producing fertilizers that feed half the world pop.

• produces -3% of global greenhouse gas emissions

Phosphorus cycle

• biogeochemical cycle with two sub cycles

  • fast biological cycle (plants)

  • slow geological cycle (rocks)

Fast Biological cycle phosphorus cycle

• plants, animals, decomp, assimilation

Slow geological cycle phosporus cycle

stored in rocks—weathering—runoff—bodies of water—sedimentation—rock uplift

True cost accounting TCA

accounting approach measures values of hidden envi, social, and health impacts of econ activities,

• costs not reflected in market price of goods. Applied to food systems to see full cost of life cycle

Crop rotation

• growing series of diff crops in same area across seasons.

• reduces dependance on fert, disrupts pests life cycles, manages weeds, improves soil fertility compared to monocropping

Integrated pest management (IPM)

• adding beneficial insects, growing resistant plants, pesticides

• manage pests with minimizing envi risk,

• not organic, but reduces pesticide use

Organic (food label)

• USDA certification indicating a food was produced in cycled resources, conserve bio, preserve eco balance

• requirements differ from produce, meat, dairy, and packaged goods

Fair trade certification

• ensures farmers receive fair price for commodities, meet minimum standards for working conditions, prohibit child labor, and have plans to improve bio and soil health

• only applicable to agricultural products

Modern food system

• characterizes econs of scale, global trade, industrialize, monoculture, heavy use of fertilizer and pesticides

• hunger is primarily a prob of unequal distribution, not total food production

Modern food system benefits

• decreased food prices (US spend <5% income on food)

• increased food variety and access, global food supply per capita up 30% since 1961

• 1 billion jobs globally

Modern food systems drawbacks

• envi degration (soil, water, climate, biodiverity)

• eutrophication, unhealthy food options

• food waste

Modern food systems history

• Agri Rev (10,000 BC): crop domestication, specialization Global trade (salt, spices)

• Indust Rev: mechanization, chemistry

• Green Rev (20th cent): high yeild crops, fertilizers, pesticides,

Nitrogen Cycle

• Nitro makes up 2.6% of living matter but 80% of atmosphere as unusable N2

• All steps driven by bacteria

• HBP bypasses natural fixation, increasing nitrogen input into biosphere

• 50% of nitrogen in human tissue originated from HBP

• world pop could not be sustained at current levels without synthetic nitrogen fertilizers

Nitrogen Cycle Steps

• Fixation- ammonification- nitrification- assimilation- denitrification

Phosphorus cycle

• essential for DNA, cell membranes (phospholipids) and bones (calcium phosphate

• Bio fast sub cycle

• Geo slow cycle

• no atmospheric reservoir (unlike nitrogen) once lost to ocean sediment, gone to human timescales

How phosphorus fertilizers are produced

• grinding phosphate rock

• reacting with sulfuric acid to make phosporic acid

• then combined with ammonia

Eutrophication

• Law of the Minimum explains which nutrient triggers bloom in each ecosystem

Mechanisms of Eutrophication

• Excess nutrients enter water (fert runnoff, sewage, wastewater)

• Algal bloom occurs (rapid growth of micro)

• Bloom died off when nutrients are exhausted

• bacteria decompose dead algae, consuming dissolved oxegyen

• oxygen depletion (hypoxia) occurs

• aquatic life suffocates- dead zones form

Sustainable food solutions

• true cost accounting

• crop rotation

• IPM

• Food lables guide consumers: Organic, fair trade, Food alliance, rainforest alliance, salmon safe, certified humane

• eating lower on food chain reduces grain use: beef requires 7x more grain per pound than bread

Methods/tech developed during green rev

• high yield variety cereal crops (dwarf wheat, HY rice) through selective breeding

• widespread into of synthetic chem fertilizers (nitrogen and phosph based)

• Exapnsion of controlled and planned irrigation systems

• Introduction of pesticides

Pros of modern food system

• Greater variety of foods available year round

• massive employment- makes 1 billion jobs

Cons of modern Food system

• envi degration: soil depletion, deforestation, water scarcity

• Unhealthy food options, heavily processed, high in fat/sugar, additives

HBP inputs

• Atmospheric dinitrogen (N2) + hydrogen gas( H2 sourced from natural gas, methane CH4)

• reaction: N2+3H2—> 2NH3 (ammonia)

HBP outputs

• Ammonia (Nh3) processed into urea or ammonium nitrate fertilizers

HBP benefits

• makes nitrogen fert available at massive scale

• supports food production for half global pop

• 50% of nitrogen in human body orginiated from HBP

Key differences in freshwater v saltwater eurphocation

• triggering nutrient differs: phosphorus limits fresh, nitrogen limits salt

• Bloom organisms differ: cyanobacteria in fresh, dinoflagelletes and diatoms in salt

• Stratification: purely thermal in lakes; thermal+ salinity based (halocline) in oceans

• Scale: lake dead zones are localized and seasonal; marine deadzones are large and recurring.

why lake erie dead zone is confined to bottom

• during summer lake stratifies thermally, warm upper layer sits above cold bottom layer (seperated by thermocline)

• Prevents mixing, oxegyn cannot reach bottom, algae blom at surface then die and sink

• bacteria decompose them at depth comsuming oxegyn

lake erie seasonal recovery

• in fall surface waters cool, density difference between layers disappears

• lake turns over, wind driven mixing, re-oxygenating bottom

• dead zone breaks down until strat returns in summer

How crop rotation reduces need for fert

• allows soil to recover as diff species take up diff nutrients and add diff organic matter

• disrupts pests and weed cycles, reducing need for pesticides

Role of Legumes

• symbiotic relationship with nitrogen fixing bacteria in root nodules

• bacteria converts atmospheric N2 into ammonia into the soil, replenishing nitrates

• planting legumes in rotation acts as a biological nitrogen fertilizer, reducing need for synthetic fertilizer

Is IMP organic?

no, organic farming prohibits synthetic pesticides entirely

Requirements for produce and grains to meet USDA organic labl

• natural fertalizers

• eco friendly pest control

• protect soil and water quality

meat dairy ad eggs Organic requirements

• animals raised on pasture

• humane treatment

• no growth hormones or antibiotics

Packaged goods organic requirements

• No GMOs

• Traceable from farm to store

• no artificial colors, flavors, or preservatives

What does fair trade cert not specify

• exact biodiversity or soil health practices to be used (plans required, not methods)

• only applies to agricultural products

What is Not a step in eutrophication

depletion of nitrogen in the body of water

What is true about fair trade

Only agricultural products can be certified

Eutrophication steps

Nutrient increase- algal bloom- decomp- oxygen depletion- dead zone

Why is lake eries dead zone bottom confined

• thermal stratification traps decomposing matter and depletes oxygen at depth

Gulf of Mex dead zone is driven by nitrogen runoff from which source

agricultural runoff carried by the Mississippi River

What is eutrophication

process in which nutrients accumulate in a body of water, leading to increase organism growth that may deplete oxygen

What is a HAB

an algal bloom that causes negative impacts to other organisms in the ecosystem

what does term Hypoxia mean in the context of aquatic ecosystems

• the depletion of dissolved oxygen in water, causing environmental degradation

Humans began to depend on monoculture starting during the

Agricultural revolution (10,000 BC)

The slow sub cycle of the phosphorus cycle contains all of the following expect

• rocks, bodies of water, runoff

• EXCEPT PLANTS