Global Environment - How Does Soil Form?

Global Environment

Lecture

October 27, 2015

How does soil form?

• Parent material – the mineral material on which the soil is formed
• Climate – affects temperature and moisture of soil
• Topography – influences movement of water over soil
• Biological activity

• Influences soil compaction and nutrients in the soil
• Plant material (using carbon from the air) breaks down into soil
• a few inches of soil is responsible for all of the growing things on the planet - plants, animals, people including all of the food

Flow of nutrients through food systems

• food production is a way of redistributing nutrients to human bodies
• displacement of nutrients is especially a problem for rain forests, where the soil is poor and most of the nutrients are in the vegetation (which gets removed as exotic wood)
• the more we deplete the harder it is to grow food

(Recent) history of agriculture

Silent Spring

• birds died from DDT which is used to control mosquitoes
• Published in 1962 (Rachel Carson)
• Credited with helping start the modern environmental movement
• Detailed the effects of heavy pesticide use (esp. DDT)
• DDT was being used to combat insect pests
• Thin egg shells in birds
• Cancer in humans
• DDT still used for malaria control elsewhere in the world

Why all the pesticides?

• Because of the natural contradiction btw population and production of food

Famine: inefficiency of medieval agriculture

Standardization: A few changes in global food systems greatly increased reliability and productivity of agriculture

Potato end famine in medieval Europe: manure (nitrogen- and phosphate-rich)

Agriculture before the 19th century

• Planting and harvesting often still done by hand
• Seeds are selected for desired traits from year to year
• Manure is the primary fertilizer

19th Century Guano Island

• New source of fertilization

Nitrogen and phosphate rich Guano as fertilizer (late 19th century)

Improved yield and farm new land

Agro-industrial complex

• nutritious crops and abundant fertilizer were the first two components of the agroindustrial complex

Prairie: the almost perfect agricultural landscape

• fertile soils
• Deep soil with lots of organic matter
• Limestone bedrock prevents acidification
• Problem: erosion; grasses have extensive root system

Tropical rain forest have the poorest soil: nutrients are at the canopy levels and middle levels and all the insects

Standardization on the grain farm

• Dense roots: prairie root system encouraged specialized “breakers” who owned heavy steel plows and moved from farm to farm.
• seed drill made planting more efficient in terms of:

• planting ratio
• amount of labor required

• Manual broadcasting means some seeds would land on the hills instead of the furrows and wouldn’t be at the right depth.
• seed drill improves productivity by as much as 9 times

Agro-industrial complex

• All four technologies came together to enhance production in the New World (and elsewhere).
• This ensemble could be applied almost anywhere (though grasslands were still be cheapest land to convert)

Flatboats and the grain trade

• farmers sold grain to merchants, brought to waterways by wagon
• Grain was shipped in flatboats like this one to cities.
• Merchants retained ownership and didn’t get paid until it reached its destination, and therefore carried a lot of risk
• There was therefore a close relationship between the grain itself and the grain as a salable commodity.

Railroads

• Railroad was successful not because it was inherently cheaper, although it was faster and made high-volume shipping easier.

• Fixed costs were large (construction and maintenance, and even fuel and labor), were surprisingly fixed no matter much was being shipped.
• RR lines gave the best rates to the longest journeys. Thus, those that terminated in Chicago or other urban centers were the cheapest.

• This encouraged shipping from one city to another directly, enhancing its importance as a center of trade
• faster
• potentially cheaper (but required long distances because of fixed costs)

[pic 1]

Mechanization [pic 2]

Standardization

Overcoming Local conditions

• together, these technologies allowed industrialized societies to overcome many of the traditional limitations to population growth and food production

Green Revolution 1945-1965

• began in the 1940s in Mexico
• efforts to develop (by crossbreeding) new, high-yield crop varieties to solve hunger problems
• used inbred individuals with highly predictable “phenotypes”
• new crops required higher inputs of fertilizer, pesticide and water

Irrigation

• irrigated land worldwide has more than tripled since the 1950s

Fertilizer

• inputs have increased 4x in the last 50 years
• allows otherwise unproductive land to be farmed
• input nitrogen (many plants can’t “fix it” ) but also phosphorus and potassium
• manure is still important as fertilizer in poorer parts of the world, but doesn’t yield as much as inorganic fertilizers

Pesticides

• Large-scale use of pesticides began in the 1950s.
• In the 1960s it became known that DDT and others were harmful to wildlife, especially birds (Silent Spring)‏
• New pesticides were developed in the 1970s

• insects were developing resistance to older ones

Green Revolution success in India

• New rice variety produced 3 times more rice per acre than traditional varieties
• World rice prices dropped from $550/ton in the 1970s to $200/ton in 2001
• “Solved” hunger problems in India in the 1960s-70s

Social Concerns about Green Revolution Technology