evr- agriculture and food supply 2

Horizons

A series of layers of the earth; OABC

O horizon

organic layer on top of soil

A (& E in some soils) horizon

upper horizon

B horizon

zone of accumulation

C horizon

most similar to parent material

Soil fertility

Capacity of soil to supply nutrients necessary for plant growth; Geologically younger soils are typically more fertile

Soil drainage

Soils with high clay content hold water well. Soils with high sand content drain very well.

Erosion

the transport of soil from one location to another by wind or water; agriculture can accelerate erosion by 100x per year (ex. Dust Bowl)

Dust Bowl

Combination of plowing prairie with intense drought loosened soil over vast areas, paired with wind, resulting in massive, continuous dust storms

Desertification

conversion of productive lands to desert

Intensification

alternative to issue with land being stretched to the limit

Centralization in meat production

One example of the impacts of industrial agriculture

1. Broad spectrum inorganic toxins (toxic to all organisms)

2. Petroleum based sprays and natural plant chemicals (not as effective)

3. Artificial organic compounds (DDT, toxic to humans, pests developed resistance)

4. Return to biological and ecological knowledge (IMP, Biological control, engineered to target only pests effectively)

The industrial revolution brought major changes in agricultural pest control (4 stages)

IPM

integrated pest management: goal is to reduce use of artificial pesticides

Biological control

use of biological predators, sex pheromones to bait traps

Organochlorine

target sodium ion channels in nerve cells of insects

Organophosphate

block electrical transmissions across nerve cells

Develop plant characteristics that increase the amount of food that can be grown through GMFs

How does plant breeding increase agricultural productivity?

Polygenic traits

Used in GMF to slowly improve over many generations by selectively choosing best traits and reproducing

Single gene traits

Many useful traits are controlled by a single gene. When mutations occur they can sometimes have large effects

Marker assisted selection

a technique to let you know if the gene you want is present

Genetically modified organisms (GMO’s)

Organisms that have had their genome altered through modern technology

1. Trial and error

2. Stimulation of mutations

3. Genetic analysis of seeds

4. Turning genes on or off

5. Moving genes from one species to another

The process of plant breeding

Transgenic organisms

Directly modifies genes through molecular biology: combines genes of two different species

Genetic engineering is already transforming the U.S. food supply and many crops are now genetically modified

Prevalence of GM foods

Environmental, humanitarian, and potentially reduce use for herbicides and chemicals in farming

Benefits of GMOs

Health risks, transgene pollution, evolved pest resistance to GM crops

Scientific concerns about GMO’s

“Superweeds”

Transgenes can jump from crops to weeds and change their genes, which hurts wild plants

Nearby plants must be genetically similar and many traits of crops are not beneficial to wild plants

Why transgenes will likely not persist in wild plants or weeds?

Prevent cross pollination (male sterility, flowering time, removal of transgene from pollen) and decrease chance of survival (dwarfism, terminator gene)

How can we prevent transgenes from getting into other plants?

Dwarfism

Coupling of transgene with mitigating gene

Terminator Gene

Selectively terminable transgenic lines

In US, GM foods were introduced and accepted with relatively little public debate, controlled by major corporations

Europe vs. America in GMF’s

1. Non-industrial fertilizers (manure or other animal by-products). Breakdown slowly: more nutrients absorbed by plants

2. No synthetic pesticides (integrated pest management, rotate crops, biological controls, pest trapping)

3. No genetic engineering

4. Follow above standard for 3 years

USDA Regulations for Organic Crops

Adv: Lower environmental impact, better nutrition (maybe)

Dis: Higher cost, lower yield in most economically developed countries

Organic Agriculture Adv and Disadv

Aquaculture

farming of food in aquatic habitats; important protein source, no space shortage, productive, growing globally, but has environmental concerns from small enclosures, waste pollution, and potential damage to local biological diversity