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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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