1. Agriculture, Aquaculture and the Environment
Chapter 11
Agriculture, Aquaculture and the Environment

2. An Ecological Perspective on Agriculture (Agroecosystems)
Try to stop ecological succession and keep the agroecosystem in an early successional state
Monoculture: Large areas planted with a single species
Decreases organic matter in the soil
Simplifies ecosystem so vulnerable to disease outbreaks
Crops are planted in neat rows (easy for pests)
Require plowing (unnatural soil disturbance)
Genetic modification of crops becoming more common.
Agricultural Globalization

4. Can we feed the World?
*History of agriculture is a series of human attempts to overcome environmental limitations and problems
*Each new solution has created new environmental problems
*Food supply greatly influenced by social disruptions and social atttitudes

5. How We Starve Undernourishment Malnourishment
Lack of sufficient calories in available food
Malnourishment
Lack of specific chemical component of food
Supply of protein has been the major nutritional quality problem (animals?)
Varying weather patterns; inadequate international trade in food; civil strife

7. Food Aid Programs
Where one nation provides food to another or give or lends money to purchase food
Can lower food prices
Can reduce local food production
Can undercut the local farmers

8. World's Major Crops
Most of world's food provided by only 14 species (wheat, rice, soybeans)
Forage crops:
Food for domestic animals
Rangeland:
Provides food for grazing and browsing animals without plowing and planting (can be easily damaged)
Pasture:
Plowed, planted and harvested to provide forage for animals

11. Grazing on Rangelands
Overgrazing occurs when the carrying capacity is exceeded. It can cause severe damage to lands.
Trampling stream banks; animal waste
Slows vegetation growth
Reduces plant diversity
Leads to dominance by plant species undesirable to cattle
Hastens soil erosion as plant cover decreases

12. Grazing on Rangelands
It is important to properly manage livestock, including using appropriate lands for grazing and keeping livestock at a sustainable density
Density related to rainfall amounts

13. Agricultural Practices
Modern Industrialized Practices:
-cattle initially on open range then transferred to feedlots
-feedlots have an intense use of resources; manure in streams
Traditional Herding Practices:
-overgrazing
-environmental impact ties in with density, rainfall and soil fertility

15. Soils
-Earth materials modified over time by physical, chemical and biological processes into layers
-Soil horizons not necessarily present in any one soil
-Fertility: combination of the capacity of a soil to supply nutrients necessary for plant growth, to store water (yet not waterlogged) and allow for air flow
-Soils today are eroding faster than being generated

17. Restoring our Soils 1. Macronutrients Fertilizers: N-P-K
Limiting Factor: The single requirement for growth available in the least supply in comparison to the need of an organism
Liebig’s “Law of the Minimum”
Two Types of Life-Important Chemicals
1. Macronutrients
2. Micronutrients
Synergistic Effects: a change in availability of one resource affects the response of an organism to some other resource

18. Controlling Pests Undesirable competitors, parasites or predators
Insects
Weeds (major problem)
Early successors
Compete for resources, light, water, nutrients and space

19. History of Pesticides
Before the Industrial Revolution, pests removed or farming methods used to decrease
Broad Spectrum Inorganic Compound
“Magic Bullet”
Petroleum Based Sprays and Natural Plant Chemicals (nicotine)
Artificial Compounds (DDT)
Biological control
Predators, parasites and competitors
Integrated Pest Management

20. Integrated Pest Management
Control of agricultural pests (rather than complete elimination) using several methods together, including biological and chemical agents
No or low-till agriculture
Spatial complexity and biological diversity
Less damaging
Goals:
To minimize the use of artificial chemicals
To prevent or slow the buildup of resistance by pests to chemical pesticides

22. Future of Agriculture *Modern Mechanized Agriculture *Resource Based
-based on highly mechanized technology; high demand for resources with little use of biologically based technology
*Resource Based
-based on biological technology and conservation of land, water and energy
*Genetic Engineering

23. Future of Agriculture *Increased production per acre (GMC)
*Increased farmland area (Food vs fuel)
*New crops and hybrids (release land, higher yield, disease resistance, etc.)
*Better irrigation (drip)
*Organic farming (more natural, minimizes environmental impact, etc.)
*Eating lower on the food chain

24. New Hybrids Occurs naturally Increase in agricultural productivity
Concerns:
Superhybrids
Superweeds
Marginal lands

25. The Terminator Gene
A genetically modified crop which has a gene to cause the plant to become sterile after the first year
In theory, the gene prevents genetically modified crops from spreading
Protected “corporately”
Poor nations

26. Aquaculture *Farming of marine and freshwater habitats
*High nutritional quality
*Carp, tilapia, oysters, shrimp
*Production on per area basis (flowing water brings food from outside into the pond or enclosure)
*Negatives – waste released to connected waterways; can damage biological diversity