An Ecological Perspective (BIOL 346)

Talk Five:Sustainable Agriculture

Sustainable Agriculture• The practice of farming using principles of ecology, the

study of relationships between organisms and their environment. – It has been defined as "an integrated system of plant

and animal production practices having a site-specific application that will last over the long term:

• Satisfy human food and fiber needs• Enhance environmental quality and the natural resource

base upon which the agricultural economy depends• Make the most efficient use of non-renewable

resources and on-farm resources and integrate, where appropriate, natural biological cycles and controls

• Sustain the economic viability of farm operations• Enhance the quality of life for farmers and society as a

whole.

Sustainable agriculture integrates three main goals

• Environmental health

• Economic profitability

• Social and economic equity.

Environmental health• Sustainable

Agriculture refers to agricultural production that can be maintained without harming the environment.

• Environmentally Sustainable Agriculture should be:– Bearable– Equitable– viable for the farmer

• AND - produce the best produce the best quality food for the quality food for the consumer, nurture the consumer, nurture the environment & preserve environment & preserve energy. energy.

Economic profitability• Ecological economics is:

– the interdependence of ‘human economies and natural ecosystems’.

• It treats the economy and society as a subsystem of the ecosystem: – with emphasis on

preserving natural capital

• recognizes – That social and economic

systems cannot exist independently from the environment.

Social and economic equity• There is a natural market

premium

• If successful– Equity will be recognized

by the farmer as beneficial for this commitment to quality food output.

• In addition farmer may get– Government favorable

interest rate financial incentives and solution support.

Sustainable agriculture

• Sustainable agriculture in the United States was addressed by the 1990 farm bill.

• More recently, as consumer and retail demand for sustainable products has risen, organizations such as Food Alliance and Protected Harvest have started to provide measurement standards and certification programs for what constitutes a sustainable grown crop

What is Sustainable Agriculture?

• Agriculture has changed dramatically, especially since the end of World War II.

• Food and fiber productivity soared due to new technologies, mechanization, increased chemical use, specialization and government policies that favored maximizing production.

• These changes allowed fewer farmers with reduced labor demands to produce the majority of the food and fiber in the U.S.

What is Sustainable Agriculture?

• Has had major social and ecological impacts, which have drawn intense praise and equally intense criticism.

• In fact, many regions of the world peaked in food production in the period 1980 to 1995

• Are presently in decline, since desertification and critical water supplies have become limiting factors in a number of world regions.

What is Sustainable Agriculture?

• Although these changes have had many positive effects and reduced many risks in farming, there have also been significant costs.

Prominent among these are:• Topsoil depletion, • groundwater contamination • decline of family farms, • continued neglect of the living and working

conditions for farm laborers, • increasing costs of production• disintegration of economic and social conditions

in rural communities.

What is Sustainable Agriculture?

• A growing movement has emerged during the past two decades to question the role of the agricultural establishment in promoting practices that contribute to these social problems.

• Today this movement for sustainable agriculture is garnering increasing support and acceptance within mainstream agriculture.

• Not only does sustainable agriculture address many environmental and social concerns, but it offers innovative and economically viable opportunities for growers, laborers, consumers, policymakers and many others in the entire food system.

• The atmosphere sustains life and is sustained by life.

• The Gaia hypothesis– The entire planet is a

living breathing organism and will protect itself – homeostasis of the whole planet!!!

• The biosphere works in “cycles”

• Nitrogen• Carbon• Water

The Biosphere

• Some greenhouse emissions related to agriculture are embedded in other sectors

• fossil fuels to produce chemical fertilizers and pesticides

• Processing

• Packaging

• Refrigeration

• transport of food

• land conversion from biodiverse ecosystems to giant, monoculture food plantations

Rodale Institute study

• projects that the planet’s 3.5 billion tillable acres could sequester nearly 40 percent of current CO2 emissions if they were converted to “regenerative” organic agriculture practices

• Remember:• Via photosynthesis, over 100

billion metric tons of CO2 and H2O are converted into cellulose and other plant products

Many studies have drawn similar conclusions.

• India– organic farming research shows increases in

carbon absorption by up to 55 percent (even higher when agro-forestry is added into the mix), and water holding capacity is increased by 10 percent.

• California – study of 20 commercial farms found that organic

fields had 28 percent more carbon in the soil than industrial farms.

• The resulting water vapor mixes with the atmosphere

• At high altitudes where the air is cold enough it condenses to form rain and snow

• Falls back to Earth.

Water cycle

• Water evaporates from bodies of fresh water and the oceans

• Much water is lost from the leaves of plants via transpiration.

• Also from respiration of almost all living species

Water Cycle

Water• In some areas, sufficient

rainfall is available for crop growth, but many other areas require irrigation.

• For irrigation systems to be sustainable they require proper management (to avoid salinization) and must not use more water from their source than is naturally replenished taken from an article by Robert Service in Science

Magazine. “Energy demands on water resources”

Indicators for sustainable water resource development are:

• Internal renewable water resources. – This is the average annual flow of rivers and groundwater

generated from endogenous precipitation.

• Can be expressed in three different units: – in absolute terms (km3/yr), – a measure of the humidity of the country (mm/yr) – as a function of population (m3/person per yr).

• Global renewable water resources. – sum of internal renewable water resources and incoming flow

originating outside the country. – can vary with time if upstream development reduces water

availability at the border.

Indicators for sustainable water resource development

are:• Dependency ratio.

– This is the proportion of the global renewable water resources originating outside the country, expressed in percentage.

– It is an expression of the level to which the water resources of a country depend on neighboring countries.

• Water withdrawal. – When expressed in percentage of water resources, it shows the

degree of pressure on water resources.

– A rough estimate shows that if water withdrawal exceeds a quarter of global renewable water resources of a country, water can be considered a limiting factor to development.

– Therefore, the pressure on water resources can have a direct impact on all sectors, from agriculture to environment and fisheries.

The Soil• The biggest

ecosystem on Earth!

• Animals:– micro-organisms mix soils as they

form burrows and pores, allowing moisture and gases to move about. In the same way, plant roots open channels in soils.

• Plants: – deep taproots can penetrate

many meters through the different soil layers to bring up nutrients from deeper in the profile.

– fibrous roots that spread out near the soil surface have roots that are easily decomposed, adding organic matter.

The Soil• Micro-organisms:

– including fungi and bacteria, effect chemical exchanges between roots and soil and act as a reserve of nutrients.

•  Humans: – impact soil formation by

removing vegetation cover with erosion as the result.

– Also mix the different soil layers, restarting the soil formation process as less weathered material is mixed with the more developed upper layers.

Soil Erosion• Fast becoming one of the worlds greatest problems. It

is estimated that more than a thousand million tonnes of southern Africa's soil are eroded every year.– Experts predict that crop yields will be halved within

thirty to fifty years if erosion continues at present rates.

• Not unique to Africa but is occurring worldwide. – The phenomenon is being called Peak Soil as present large

scale factory farming techniques are jeopardizing humanity's ability to grow food in the present and in the future.

• Without efforts to improve soil management practices, the availability of arable soil will become increasingly problematic.

Soil Management techniques

• No-till farming– soil is left intact and crop residue is left on the field.– soil layers, conserving organisms and layers in their

natural state.

• Keyline design – maximizes beneficial use of water resources of a

piece of land. – refers to a specific topographic feature linked to

water flow

• Growing wind breaks to hold the soil – Planting trees and hedges– Prevent wind from blowing away top soil

Soil Management techniques

• Incorporating organic matter back into fields– Composting! Puts Carbon, Nitrogen, Oxygen, Water and

microbes back into the soil!!! Can also add Urine –honest!!

• Stop using chemical fertilizers (contain salt)– Remember Algal Blooms? Also, the salt kills natural

micro-organisms in soil – contaminates water!!!!!

• Protecting soil from water runoff– Careful placement of rocks and trees.

• Soil Steaming–  sterilize soil with steam in open fields or greenhouses– Destroys pathogens– Destroys weeds, but dead plant material is left in soil as

compost

Nitrogen in the environment• Present in many forms

• 78% of atmosphere is N2

– Most of this is NOT available to living organisms

• Getting N2 for the atmosphere requires breaking the triple bond between N2 gas to produce:

• Ammonia (NH3)

• Nitrate (NO3-)

• So, N2 has to be fixed from the atmosphere so plants can use it

Nitrogen in the environment• This occurs naturally

by:-Lightning:– 8%: splits H2O: the free O

and H attack N2 – forms HNO3 (nitric acid) which fall to ground with rain

• Photochemical reactions:– 2%: photochemical

reactions between NO gas and O3 to give HNO3

• Nitrogen fixation:– 90%: biological – bacteria

fix N2 to ammonium (NH4+)

Nitrogen in the environment

• Once fixed in ammonium or nitrate :-– N2 enters biochemical cycle

– Passes through several organic or inorganic forms before it returns to molecular nitrogen

– The ammonium (NH4+) and

nitrate (NO3-) ions generated

via fixation are the object of fierce competition between plants and microorganisms

– Plants have developed ways to get these from the soil as fast as possible

How do plants get their nitrogen?• Some plant species are

Legumes.

• Legumes seedlings germinate without any association to rhizobia– Under nitrogen limiting

conditions, the plant and the bacteria seek each other out by an elaborate exchange of signals

• The first stage of the association is the migration of the bacteria through the soil towards the host plant

How do plants get their nitrogen?• Nodule formation results a

finely tuned interaction between the bacteria and the host plant– Involves the

recognition of specific signals between the symbiotic bacteria and the host plant

• The bacteria forms NH3 which can be used directly by the plant

• The plant gives the bacteria organic nutrients.

Bottom line• Grow crops which

are best suited to local environment

• Have a plentiful, and renewable local water supply

• Protect the soil

• Good crop management techniques

Good crop management techniques

• Grow a variety of crops. – spreads economic risk and are

less susceptible to the radical price fluctuations associated with changes in supply and demand.

• Crop rotation – used to suppress weeds,

pathogens and insect pests.

Good crop management techniques

• Cover crops – stabilizing effects by holding

soil and nutrients in place

– conserving soil moisture with mowed or standing dead mulches, increasing the water infiltration rate and soil water holding capacity.

– The use of vineyards can buffer the system against pest infestations by increasing beneficial arthropod populations and can therefore reduce the need for chemical

inputs. 

Bottom line• Low cost and

effective local storage of food stuffs

• Low environmental impact transport system

• Local market and a steady and growing customer base.

So what about backyard Agricultural

Sustainability?• Grow only crops which mature within the local

growing season.

• Only grow crops selections which will work together in such a limited space.

• Think about nutrient needs.

• Think about water demands.

• Think about long time storage of successful crops.

Water barrel• Free (clean) water!!!!!!!

• Rain barrel kit – www.earthminded.com– Trash can– $40.00!!!

• Set up next to garden. Fills up fast!– Melting snow will also fill it up.– Can connect many together.

• Consider county, city, and state laws!

Composting• Turning kitchen waste into

natural fertilizer

• Any container will work– Need air holes

• Can buy bacteria cultures to add to container.– Can add worms to increase

efficiently

• When setting up, layer soil and kitchen waste.– Takes approx. one year to get

going from scratch.

Wood ash• In addition to composting,

can use wood ash from a log burning fireplace.

• Ash is full of the essential nutrients required for plant growth and development.

• Even contains a higher % of these nutrients than commercially available growth supplements.

• Cheap, natural, and fantastic for the environment and soil health

ComponentNormal agar (ppm)

Ash Agar (ppm)

Arsenic <0.1 0.1

Barium <0.1 3.3

Boron 0.1 2.2

Calcium 37.9 1409.9

Chlorine 2.1 2.1

Chromium <0.1 0.1

Cobalt 0.1 0.1

Copper 0.1 2.2

Iron 0.5 27.4

Lead 0.1 0.2

Lithium <0.1 0.2

Magnesium 11.6 107.6

Manganese 0.2 3.8

Molybdenum <0.1 0.1

Nitrogen 21.5 21.5

Phosphorus 3.6 109.4

Potassium 35.6 552.1

Sodium 83.7 90.7

Sulfur 268.3 335.8

Tin 0.1 0.1

Zinc 0.1 1.1

Canning• So, you grew hundreds of

tomatoes. What to do with them?

• Great preservation technique.– Allows you to store food stuffs

outside of the growing season– Can use them for cooking for the

rest of the year– Better than just freezing food stuffs

• Can store ANYTHING by this method.

• Not a new technology, just a (mostly) forgotten one, which is making a comeback.

Final Summary• Sustainable Agriculture is:

– The practice of farming using principles of ecology, the study of relationships between organisms and their environment.

– refers to agricultural production that can be maintained

without harming the environment.

• Not only does it address many environmental and social concerns, but it:– offers innovative and economically viable opportunities for:– growers – Laborers– Consumers– policymakers.

The End!

Any Questions?