1. Soil and Agriculture Review Notes
Industrialized Agriculture
Soil Degradation
Overgrazing
Food Security
Green Revolution
Feedlot Agriculture
Food Choices

2. Soil: The Foundation for Sustainable Agriculture
Agriculture = practice of raising crops and livestock for human use and consumption
Cropland = land used to raise plants for human use
Rangeland or pasture = land used for grazing livestock
Land devoted to agriculture covers 38% of Earth’s land

3. Agriculture arose 10,000 years ago
Different cultures independently invented agriculture
Evidence for the earliest plant and animal domestication is from the “Fertile Crescent” of the Middle East
Agriculture rose independently in at least China, Africa, and the Americas
Raising crops was a positive feedback cycle
Harvesting the crops required people to be sedentary
Being sedentary encouraged the planting of more crops and production of more food
More crops allowed larger populations
Larger populations required planting more crops

5. Industrialized Agriculture
Traditional Agriculture- performed by humans and animal muscle power with simple tools and machines
Use of polycultures
Subsistence agriculture- families produce enough food to feed themselves
Intensive- produce excess food to sell in market
Stops short of using fossil fuels
Industrialized Agriculture- large scale mechanization and fossil fuel combustion
Use of monocultures
Replaces horses and oxen
Cultivate, harvest, transport and process crops at higher yields

6. Industrialized Agriculture
Three systems produce most of our food
Croplands: 77%
Rangelands, pastures, and feedlots: 16%
Aquaculture: 7%
Importance of wheat, rice, and corn

7. Industrialized Food Production in the US
Industrialized agriculture uses about 17% of all commercial energy in the U.S. and food travels an average 2,400 kilometers from farm to plate.

8. Industrialized Agriculture
Monocultures
More efficient = increased output
Reduces biodiversity
Narrowed human diet
90% of the food consumed comes from just 15 crop species and 8 livestock species
I.A. occupies 25% of the world’s cropland
Intensive cultivation creates problems with the integrity of the soil
Bad soil = no crops = decrease in population

9. Industrialized Agriculture
About 80% of the worlds food supply is produced by industrialized agriculture.
Uses large amounts of fossil fuel energy, water, commercial fertilizers, and pesticides to produce monocultures.

10. Conserving Soil
Feeding the world’s rising human population requires changing our diet or increasing agricultural production
But land suitable for farming is running out
Mismanaged agriculture turns grasslands into deserts, removes forests, diminishes biodiversity and encourages the growth of non-native species
It also pollutes soil, air, and water with chemicals
Fertile soil is blown and washed away
We must improve the efficiency of food production while we decrease our impact on natural systems

11. Soil Degradation
Over the past 50 years, soil degradation has reduced potential rates of global grain production by 13% on cropland and 4% on rangeland
Most degradation results from cropland agriculture, overgrazing by livestock and deforestation

12. Soil Degradation Increased vulnerability through:
Over cultivating fields through poor planning or excessive tilling
Overgrazing rangelands with more livestock than land can support
Clearing forests on steep slopes or with larger clear- cuts

13. Soil Degradation
Soil degradation is especially severe in arid environments
Desertification = a form of land degradation with more than a 10% loss of productivity
Caused primarily by wind and water erosion, but also by:
Deforestation, soil compaction, and overgrazing
Drought, salinization, water depletion
Climate change
Arid and semiarid lands (drylands) are most prone to desertification
Cover about 40% of the Earth’s surface

14. Conserving the soil No-till farming has many benefits
It increases organic matter and soil biota
Reduces erosion and improves soil quality
Uses less labor, saves time, causes less wear on machinery
Prevents carbon from entering the atmosphere (carbon storage)—may help mitigate climate change
Reduces fossil fuel use due to less use of the tractors
Adds organic matter to soils that is kept from the atmosphere

16. No-till farming has many benefits
40% of U.S. farmland uses conservation tillage
Erosion rates in the United States declined from 9.1 tons/ha (3.7 tons/acre) in 1982 to 5.9 tons/ha (2.4 tons/acre) in 2003
In Brazil, Argentina, and Paraguay, over half of all cropland is now under no-till cultivation
Crop yields have increased while costs have dropped
May require increased use of herbicides and fertilizers
To minimize problems:
Use green manure (dead plants as fertilizer)
Rotate fields with cover crops

17. Overgrazing Grazing is sustainable as long as:
Do not exceed the ranges carrying capacity
Do not consume grasses faster than they can grow back/be replaces
Overgrazing occurs when many animals eat too much plant cover
Impeding regrowth
Prevents replace of biomass
Creates positive feedback loop/cycle

19. Overgrazing
Positive feedback loop- instead of stabilizing a system (negative feedback loop), they drive it further towards another extreme
When livestock remove too much plant cover, more soil is exposed and made vulnerable to erosion. Erosion makes it difficult for vegetation to regrow perpetuating the lack of cover and give rise to more erosion
Degraded soils = great home for invasive species to outcompete native plants

21. Overgrazing Overgrazing can compact soil
Harder for water to infiltrate
Harder for soils to aerate
Harder for plant roots to expand
Harder for plants to conduct cellular respiration

22. Food Security
850 million people in developing countries do not have enough to eat
Political obstacles
Inefficiencies in distribution
Every 5 seconds a child starves to death
Since 1970 we have reduced world hunger from 26% to 13%
Food security is the guarantee of an adequate and reliable food supply available to all people at all times

23. We face undernutrition, overnutrition, and malnutrition
Undernutrition = people receive fewer calories than their minimum requirements
Due to economics, politics, conflict, and inefficiencies in distribution
Malnutrition- people receive fewer vitamins, minerals, proteins and/or nutrients than minimum requirements
Most undernourished live in developing nations
But 50 million Americans are “food insecure”
Food security = guarantee of an adequate, safe, nutritious, and reliable food supply
Undernutrition has decreased since the 1960s

24. We are producing more food per person
The human population is expected to reach 9 billion by 2050
This will mean 2 billion more people to feed
Food production has exceeded population growth over the last 50 years
We produce food through technology
Fossil fuels, irrigation, fertilizer, pesticides, cultivating more land, genetic engineering
Today, soils are in decline and most arable land is already farmed

26. Green Revolution
1950s the Green Revolution introduced to the developing world to boost agricultural production:
New technology, crop varieties and farming practices
Created from the desire for greater quantity and quality of food for the growing population
Increased yields and decreased starvation
Developing countries were able to double, triple or quadruple yields

27. The Green Revolution brought mixed consequences
Depended on heavy use of:
Synthetic fertilizers and chemical pesticides
Irrigation
Fossil fuel-powered machinery
From 1900 to 2000, cultivated area increased 33% while energy inputs increased 80 times
Positive effects on the environment
Prevented some deforestation and land conversion
Preserved biodiversity and ecosystems

28. The Green Revolution
Lack of water, high costs for small farmers, and physical limits to increasing crop yields hinder expansion of the green revolution.
Since 1978 the amount of irrigated land per person has declined due to:
Depletion of underground water supplies.
Inefficient irrigation methods.
Salt build-up.
Cost of irrigating crops.

29. The Green Revolution
Modern agriculture has a greater harmful environmental impact than any human activity.
Loss of a variety of genetically different crop and livestock strains might limit raw material needed for future green and gene revolutions.
In the U.S., 97% of the food plant varieties available in the no longer exist in large quantities.

30. We are moving toward sustainable agriculture
Sustainable agriculture = agriculture that does not deplete soils faster than they form. It does not
reduce the amount of healthy soil
pollute water
decrease genetic diversity
No-till farming and other soil conservation methods help make agriculture more sustainable
Reducing fossil-fuel inputs and pollution is a key goal
Many approaches move away from the industrial agriculture model

31. Biodiversity Loss Soil Air Pollution Human Health Water
Loss and degradation of grasslands, forests, and wetlands
Erosion
Water waste
Greenhouse gas emissions from fossil fuel use
Nitrates in drinking water
Loss of fertility
Aquifer depletion
Salinization
Increased runoff and flooding from cleared land
Pesticide residues in drinking water, food, and air
Other air pollutants from fossil fuel use
Waterlogging
Fish kills from pesticide runoff
Desertification
Sediment pollution from erosion
Contamination of drinking and swimming water with disease organisms from livestock wastes
Greenhouse gas emissions of nitrous oxide from use of inorganic fertilizers
Figure 13.18
Natural capital degradation: major harmful environmental effects of food production. According to a 2002 study by the United Nations, nearly 30% of the world’s cropland has been degraded to some degree by soil erosion, salt buildup, and chemical pollution, and 17% has been seriously degraded. QUESTION: Which item in each of these categories do you think is the most harmful?
Fish kills from pesticide runoff
Killing wild predators to protect livestock
Surface and groundwater pollution from pesticides and fertilizers
Loss of genetic diversity of wild crop strains replaced by monoculture strains
Belching of the greenhouse gas methane by cattle
Bacterial contamination of meat
Overfertilization of lakes and rivers from runoff of fertilizers, livestock wastes, and food processing wastes
Pollution from pesticide sprays
Fig , p. 285

32. Green Revolution Benefit to the environment: Harm to the environment:
Used already cultivated land
Prevented some deforestation and habitat conversion
Preserved biodiversity and natural ecosystems
Harm to the environment:
Intensive application of water, fossil fuels, inorganic fertilizers and synthetic pesticides
Increases pollution, erosion, salinization and desertification

33. Raising Animals for Food
Since 1950, global meat production has increased fivefold and per capita meat consumption has doubled
As wealth and commerce increase, so does meat, milk, and egg consumption
Domestic animals raised for food increased from 7.2 billion in 1961 to 27.5 billion in 2011
Meat consumption is expected to double by 2050

34. Feedlot Agriculture
Consuming animal products has environmental, social, agricultural and economic impacts
Domesticated animals (mostly chickens) raised for food rose from 7.3 billion to 20.6 billion between 1961 and 2000

35. Feedlot Agriculture
About half of the world’s meat is produced by livestock grazing on grass.
The other half is produced under factory-like conditions (feedlots).
Factory farms/ concentrated animal feeding operations (Densely packed livestock are fed grain or fish meal).
Half of the world’s pork, poultry and beef come from feed lots
Eating more chicken and farm-raised fish and less beef and pork reduces harmful environmental impacts of meat production.

38. Feedlot Agriculture
Feedlots reduces the impact on landscape thus reducing soil degradation through overgrazing
However, feedlots are contributors to air and water pollution
Animal waste can pollute surface and groundwater
One dairy cow can produce 44,975 lbs of waste in one year
To avoid disease animals are dosed heavily with antibiotics (can create antibiotic resistance in humans)

39. Increased meat production
Trade-Offs
Animal Feedlots
Advantages
Disadvantages
Increased meat production
Need large inputs of grain, fish meal, water, and fossil fuels
Higher profits
Concentrate animal wastes that can pollute water
Less land use
Reduced overgrazing
Figure 13.21
Trade-offs: advantages and disadvantages of animal feedlots. QUESTION: Which single advantage and which single disadvantage do you think are the most important?
Reduced soil erosion
Antibiotics can increase genetic resistance to microbes in humans
Help protect biodiversity
Fig , p. 289

40. Food Choices
It is more efficient, energy wise, to eat lower on the trophic levels than to eat meat
In 1900, 10% of global grain went to feeding animals…….In % was used
By the beginning of the 21st century , we were feeding 45% of global grain production to animals

42. Efficiency of converting grain into animal protein.
Figure 13-22

43. Food Choices Sustainable agriculture- Organic agriculture
Related to low-input agriculture that uses smaller amounts of pesticides, fertilizers, growth hormones, water and fossil fuel energy
Organic agriculture
Do not use synthetic fertilizers, insecticides, fungicides or herbicides
Use biological approaches such as composting

45. Organic agriculture is booming
Organic farmers can’t keep up with demand
U.S. consumers pay $29.2 billion in 2011
Worldwide sales tripled from 2000 to 2010
Production is increasing. In 2011:
Nearly 2 million ha (4.8 million acres) in the U.S.
37 million ha (91 million acres) worldwide
But still less than 1% of total agricultural land
Two-thirds of organic agricultural land is in developing nations
30% of Mexico’s coffee production is organic

46. Sustainable Organic Agriculture
Solutions
Sustainable Organic Agriculture
More
Less
High-yield polyculture
Soil erosion
Soil salinization
Organic fertilizers
Aquifer depletion
Biological pest control
Overgrazing
Overfishing
Integrated pest management
Loss of biodiversity
Efficient irrigation
Loss of prime cropland
Perennial crops
Figure 13.33
Solutions: components of more sustainable, low-throughput agriculture based mostly on mimicking and working with nature. QUESTION: Which four solutions do you think are the most important?
Food waste
Crop rotation
Subsidies for unsustainable farming and fishing
Water-efficient crops
Soil conservation
Population growth
Subsidies for sustainable farming and fishing
Poverty
Fig , p. 302

47. Sustainable Agriculture
Results of 22 year study comparing organic and conventional farming.
Figure 13-34

48. Solutions Organic Farming
Improves soil fertility
Reduces soil erosion
Retains more water in soil during drought years
Uses about 30% less energy per unit of yield
Lowers CO2 emissions
Reduces water pollution from recycling livestock wastes
Figure 13.34
Solutions: environmental benefits of organic farming over conventional farming based on 22 years of research comparing these two systems at the Rodale Institute in Kutztown, Pennsylvania (USA). QUESTION: Which two of these benefits do you think are the most important? (Data from Paul Mader, David Dubois and David Pimentel, et al.)
Eliminates pollution from pesticides
Increases biodiversity above and below ground
Benefits wildlife such as birds and bats
Fig , p. 302

49. Sustainable Agriculture
More research, demonstration projects, government subsidies, and training can promote more sustainable organic agriculture.
Figure 13-35