ENVS 1100 Lecture Notes - Lecture 20: Drip Irrigation, Crop Yield, Soil Fertility
Agriculture and the Environment
November 4, 2014
Main Concepts:
• What is agriculture and what are the past and current trends in agriculture
practices?
• What are the consequences of agricultural practices for sustainability of soil
as a resource?
• What are some agricultural methods we can use to minimize soil degradation
and environmental damage caused by industrial agriculture?
*Interplay between agriculture, population and technology.
Agriculture – to cultivate plants or animals for food
• 200,000 years ago humans would hunt and gather for food
• 10,000 years ago there was first evidence of agriculture
• From 1200-1800 the Industrial Revolution occurred which used fossil fuels
and machinery to produce substantially higher crop yields
• In the early 1900s we were able to fix nitrogen from the atmosphere to use
as fertilizer (Haber-Bosh)
• Green Revolution – plant-breeding program from the 1940s-1960s that
dramatically increased crop yields and led the way for mechanized, large-
scale agriculture
o Coordinated, global effort to eliminate hunger by improving crop
performance and bringing modern agricultural technology to
developing countries
o Irrigation and monocultures
• In 1994, the first GMO vegetable (a tomato) was sold in the United States
*Intensification cause by industrial agriculture
• Dependence on fossil fuels
• Vast fields planted with single type of crop (monoculture)
• New crop varieties
• Pesticides
• Fertilizers
• New way of farming on massive scale
• Fed down to developing countries to help avoid starvation
Monoculture - large expansion of a single crop
• More efficient, increases output
• Devastates biodiversity
• Susceptible to disease outbreaks and pests
• Lead to nutrient depletion of the soil
• Narrows human diet – risk of feeding populations
find more resources at oneclass.com
find more resources at oneclass.com
Irrigation – water withdrawn from aquifers and waterways formed to water crops.
Some environmental problems include:
• Salinization of soil
• Depletion of ground water
• Surface subsidence due to aquifer depletion
• Depletion, pollution and salinization of water systems
Salinization and waterlogging of soil on irrigated land without adequate drainage
can decrease yield crops (builds up amount of salts in soil which interferes with
osmosis so they cannot uptake water).
• Plants take up less than half of the water we apply in irrigation
• Drip irrigation ensures only as much water needed is applied
• Computerized moisture sensors can help control water application
Salinization is easier to prevent than mitigate.
• Avoid planting crops that need a lot of water in areas prone to the problem
• Make sure water is low in salt
• Don’t over supply drip irrigation
• Allow rain to flush out
• Plant salt-tolerant crops
Organic Agriculture – farming that does not use synthetic fertilizer, pesticides or
other chemical additives like hormones
Eutrophication – nutrient enrichment of an aquatic ecosystem that stimulates
excess plant growth and disrupts normal energy uptake and matter cycles.
Fertilizers
Inorganic – industrial mined or synthetically manufactured mineral supplements
(mainly combinations of N, P and K).
Organic – natural materials (animal manure, crop residue, fresh vegetation,
compost)
• Provide nutrients
• Improve soil structure
• Improve nutrient retention
• Improve water-holding capacity
• *application of excess manure to fields can result in runoff pollution of
surface waterways and
If over-fertilization occurs, it can lead to:
• Ground water contamination
• Eutrophication of freshwater and coastal areas
• Nitrogen oxides can pollute air
• Nitrogen from fertilizers accounts for ½ the total N flux on Earth
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
In 1994, the first gmo vegetable (a tomato) was sold in the united states. Monoculture - large expansion of a single crop: more efficient, increases output, devastates biodiversity, susceptible to disease outbreaks and pests, lead to nutrient depletion of the soil, narrows human diet risk of feeding populations. Irrigation water withdrawn from aquifers and waterways formed to water crops. Some environmental problems include: salinization of soil, depletion of ground water, surface subsidence due to aquifer depletion, depletion, pollution and salinization of water systems. Organic agriculture farming that does not use synthetic fertilizer, pesticides or. Eutrophication nutrient enrichment of an aquatic ecosystem that stimulates. Inorganic industrial mined or synthetically manufactured mineral supplements. Organic natural materials (animal manure, crop residue, fresh vegetation, excess plant growth and disrupts normal energy uptake and matter cycles. Fertilizers: provide nutrients, *application of excess manure to fields can result in runoff pollution of. Improve water-holding capacity (mainly combinations of n, p and k). compost) surface waterways and.