Food Production Flashcards
Outline the timeline and location of the Neolithic Agricultural Revolution
Fertile Crescent 11,000 BC
Yangtze and Yellow River Basins 9,000 BC
New Guinea 6,000 BC
Africa, Mexico, South America 4,000 BC
USA, 3000 BC
The characteristics of the Neolithic Revolution
Hunter gatherers become settled
domestication of plants and animals
alteration of environment to make surplus - irrigation and selective breeding
labour diversified, trading economies, culture established
governments formed, social hierarchy, sedentary lifestyle and more diseases.
Outline agriculture today
Cropland uses 17% of all productive land
Rangeland occupy 33%
Before 1980s agriculture expanded by land expansion
After 1980s expansion was via yield increases
How has industrialization increased yields?
mechanization
synthetic fertilizers
irrigation
pesticides
genetic manipulation
factory farming
Environmental issues
pollution from feces into water, air, soil
altered nitrogen cycle
high water use
altered hydrologic cycle
land degradation
converted ecosystems
loss of biodiversity
potententially harmful chemicals
animal welfare
What are synthetic fertilizers made from?
nitrogen, potassium, phosphorus. Started in 1850s by dissolving bones. Production increased 110x from 1913 to 1990
How much do humans affect the Nitrogen cycle? Natural environment?
60% 210 million tonnes per year. Soil bacteria, algae, lightning, etc 140 tonnes per year.
How are fertilizers pollutants?
Enter water systems, cause eutrophication
excess nitrogen can become nitrous oxide - a greenhouse gas
can become gaseous ammonia
What affects groundwater
Soil-drainage, amount of cropland, surrounding natural vegetation
What illnesses does nitrate contamination cause?
Blue baby syndrome, cancer
How to lower Nitrogen leaching from soil
grow catch crops, use intercropping, agroforestry.
account for all major sources of Nitrogen - manure, crop residue, legume fixation
improve estimates of how much Nitrogen is needed
time correctly when crops use most Nitrogen and when leaching will happen.
How much of the world’s cropland is irrigated? what percent of the world’s food is irrigated and how much freshwater is used
17% of crops irrigated, producing 40% of food. Uses 70% of freshwater
What problems does irrigation cause?
Rising water tables cause salnization and waterlogging. Waterlogging restricts aeration and gas exchange and reduces plant growth.
depleating groundwater can cause saltwater intrusion and land subsidence, which reduces aquifer size so recharge is lessened.
How are irrigation systems inefficient?
60% of irrigated water never reaches crops. Drip irrigation could lower water use by 70%
Farmers receive subsidies, so have no reason to conserve.
flood irrigation cause runoff and spray causes evaporation.
evaporation from reservoirs exceeds industrial and domestic consumption
How have people adapted to waterlogging?
growing crops on floating beds
