Sustainable Agriculture

Agro-ecosystem

Socio-ecological systems comprised of biophysical and socio-cultural components

Argroecosystem Performance Over Time

Depends on yield and timeframe being looked at.

Soil

Taxonomy of soil for 12 macro-orders of soil

Most productive soils for agriculture

Mollisols and Alfisols

___ of Mollisols and Alfisols are found in ___

1/3, North America

Chinampas

Practiced in Meso America. Developed in marshlands with standing water. Building islands through vegetation around perimeter and farm on top of that. Fish pull silt from bottom of canals and fertilize soil; products from trees benefit the system

Slash and burn agriculture

Practiced in poor soil in tropical forests. Cutting down and burning vegetation to move fertility into the ground and make it farmable for a couple of years. Unsustainable.

Waru-waru

Practiced in Andes. High elevation with freezing temperatures. Water gives off heat slower than the Earth. The presence of water in proximity to fields creates a micro-climate that keeps the farms warm at night.

Floodplain Agriculture

Practiced in Nile River Valley. Farming along edges of river that are prone to seasonal flooding. Silt and rich material enter the farms as floods occur, resulting in highly fertile soil.

Terraced Production Systems

Found in Asia, South America with mountainous terrain. Stepped terraces specific to elevational needs.

Rain-fed Temperate Cropping Systems

Developed in Europe. Level-ground farming with rain as primary source of soil moisture. Mixture of grain, cattle and dairy production.

Specialization

As we get further into industrialization, the idea generates that farmers should focus on one crop and only farm that crop extremely well.

It reduces agrodiversity, leading to a loss of ecosystem services in agriculture, which are then substituted with “off-farm inputs (pesticides, fertilizer, etc.)"

Industrial Agriculture

A particular and unique form of agriculture characterized (in part) by specialized production and market-based distribution of crops/food. Informed by many new/popular ideas a the time (e.g. scientific rationalism, liberal economics etc.)

Components of Agroecosystems

Pests and natural enemies

Crops

Soil biota

Pollinators

Livestock

Natural habitat

Functions of Agroecosystems

Biological Control of Pests

Nutrient cycle

Disease prevention

Pollination

Weed control

Yield

La Milpa: Corn-Bean-Squash Polyculture

Corn grown on a pole. Bean uses corn to wrap around while providing wind resilience for the corn. Horizontally growing different squash provides weed suppression.

Diverse Cropping Systems and Biological Control of Pests

Intersection of crop, pest and natural enemy

Natural Enemy

Naturally evolved enemy of the pest; there are predators and parasitoids.

Predators

They will physically eat the pest (ex. Ladybug eating an aphid)

Parasitoids

Kill the pest as part of their reproductive cycle. Done by laying eggs inside of the pest and as it hatches and develops it will kill the pest.

As farmers simplify their farming towards ______, they lose ______ functions.

Specialization, Agri Ecosystem

____ of the managed honeybees in the United States are brought to ____ to pollinate the almond trees.

75%, California

Monoculture and specialization has lead to…

Loss of soil fertility and biological control of pests

Manure, guano

As fertilizer; they started bringing manure and seabird guano from abroad to Europe.

Haber-Bosch Process

In 1913 chemists created synthetic fertilizer. Introduction to early pesticides.

Green Revolution

It “formalized” industrial agriculture. It was simultaneously an agronomic, humanitarian, and political-economic project.

Industrial Argiculture Environmental Impacts

Loss of biodiversity

Fertilizer runoff contributing to deadzones

Land subsidence
Soil erosion and Declining Fertility

Green Revolution key components include..

High Yield Varieties

Monoculture

Irrigation

Large-scale mechanization

Synthetic Fertilizer

Pesticides/Herbicides

Green revolution costs can ____

Put farmers into debt

When ___ prices go up, so does the number of _______.

Food, hungry people

Principles of Agroecology

It’s a systematic approach to understand problems in the agri-food system with research conducted in collaboration with farmers. Solutions are knowledge-intensive (rather than input-intensive). biodiverse cropping systems that maximize mutualistic relationships and cropping systems that minimize the use of off-farm inputs. Plan for cropping systems that are resistant and resilient to “shocks”.