ENVIRON 102 Lecture Notes - Lecture 9: American Chestnut, Soil Conservation, Selective Breeding
4 May 2018
School
Department
Course
Professor
Agriculture and the Environment
February 24, 2015 Lecture Notes
Ex: American chestnut tree crossbred with Chinese chestnut tree because Chinese tree has
resistance to a fungus blight
o Difficult because it’s hard to pinpoint the specific genes and there are multiple
o Crossbreeding doesn’t guarantee the expression of these specific genes
Contrary to the diversity of food that we see today, many foods are not available everywhere
Agriculture: OUTLINE
What were the origins of agriculture?
What factors determine agricultural productivity?
Why has productivity generally increased, especially over the past 50 years?
What environmental challenges has high production agriculture presented?
What strategies can we employ for sustainability?
Given continued population growth and limits on agricultural production, how do we feed a
hungry world?
Origins of Agriculture
First cultivated plants domesticated approximately 10,000 years ago
o Selective breeding
o Ex: corn evolution, selecting the corn with the biggest kernels to breed
Agricultural technology associated with development of cities and complex economies
Dependent on availability of appropriate species
Also dependent on climatic conditions and often tied to major river floodplains
o Harvesting = nutrient loss
o Flooding cycles and annual import of nutrient rich silt
Importance of food
Survival (Decimation of civilizations because of lack of food – Easter Island, the Mayan Empire)
Permits population growth – and CAN reduce population growth rate
Food insecurity is correlated with conflict: cause? self-reinforcing?
o Can lead to large family sizes and conflict between hunters
Agricultural production depends on the character of soils
Clay = particles < 0.002 mm diameter
Silt = particles 0.002 – 0.05 mm diameter
Sand = particles 0.05 – 2 mm diameter
Combination of those three helps retention of water
Organic matter
Nutrients
How does this affect moisture?
Amount of topsoil – greater the amount, the better for agriculture
Soil erosion: a global problem
Humans are over 10 times more influential at moving soil than are all other natural processes
combined
Ex: Dust Bowl
Conservation districts (begin 1935)
o Government supported districts that reach out to farmers to help them employ practices
that prevent soil erosion
Causes of soil erosion: overgrazing, deforestation, cropland agriculture, industrialization, other
overexploitation
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
February 24, 2015 lecture notes resistance to a fungus blight. Ex: american chestnut tree crossbred with chinese chestnut tree because chinese tree has: difficult because it"s hard to pinpoint the specific genes and there are multiple, crossbreeding doesn"t guarantee the expression of these specific genes. Contrary to the diversity of food that we see today, many foods are not available everywhere. First cultivated plants domesticated approximately 10,000 years ago: selective breeding, ex: corn evolution, selecting the corn with the biggest kernels to breed. Agricultural technology associated with development of cities and complex economies. Also dependent on climatic conditions and often tied to major river floodplains: harvesting = nutrient loss, flooding cycles and annual import of nutrient rich silt. Agricultural production depends on the character of soils. Clay = particles < 0. 002 mm diameter. Food insecurity is correlated with conflict: cause? self-reinforcing: can lead to large family sizes and conflict between hunters.
