Ch.12 Food and Soil Resources

Case Study: Growing Perennial Crops on the Kansas Prairie by Copying Nature

• Land Institute attempting to work with Midwestern agriculture

• Utilizing perennial polyculture to improve crop yields

12-1 How is food produced

What Systems Provide Us with Food? The Challenges Ahead

• Croplands, rangelands, ocean fisheries = food supply.

• Increase in global food production since 1950 due to technological advances.

• Analysts fear environmental issues such as pollution, overfishing, overgrazing, etc. will limit future food production.

What Plants and Animals Feed the World? Our Three Most Important

Crops• 14 plants and 8 animal

species supply 90% of global calorie intake.

• Wheat, rice, corn provide more than half the calories people consume.

• Poverty is the reason why most people cannot afford meat.

• Fish and shellfish provide 7% of the world’s food.

What Are The Major Types of Food Production? High-Input and Low-

Input Agriculture• Two types of agriculture- industrial and

traditional.

• Livestock production in developed countries= industrialized.

• Cattle brought to feedlots where they are fattened up before slaughter.

• Two types of traditional agriculture- subsistence and intensive.

12-2 Producing food by green revolution and traditional

techniques

• Most increase in global food production results from increased yields per unit of area of cropland with green revolution.

• (1950-1970) first Green Revolution

• (1967 - ) second Green Revolution

• Protects biodiversity

• Uses 8% of world’s oil output

Green Revolution• Steps:

1. Develop and plant monocultures

2. Use fertilizers, pesticides, and water

3. Multiple cropping

• For selectively bred or genetically engineered high-yield varieties of crops.

Case Study: Industrial Food Production in the United States: A

Success Story• Big companies and family-owned farms have

taken control of ¾ of U.S. food production.• Green revolution has increased crop yields,

keeping erodible land from being converted to farming.

• U.S. farm products cost 1/3 of what they did in 1910.

• Industrialization of agriculture made possible by availability of cheap energy.

What Growing techniques are used in Traditional Agriculture? Low Input

Agrodiversity in action

• 1/5 of world’s food grown on ¾ of cultivated land.

• Many farmers use interplanting

• 4 strategies:– Polyvarietal cultivation– Intercropping– Agroforestry– Polyculture

Growing Techniques Usedin Traditional Agriculture

• low-input agriculture to produce a variety of different crops on each plot of land.

• Many traditional farmers simultaneously grow several crops on the same plot, a practice known as interplanting.

• Polyvarietal cultivation, involves planting a plot with several varieties of the same crop.

• Intercropping, growing two or more different crops at the same time on a plot

• agroforestry, or alley cropping, in which crops and trees are grown together• polyculture, in which many different plants maturing at various times are planted together.• ecological research found that on average, low-input polyculture produces higher yields per hectare of land

than high-input monoculture.• Traditional farmers in arid with low natural soil fertility have

developed innovative methods to boost crop production.

Low-Tech Sustainable Agriculture in Africa

• Pedro Sanchez awarded World Food Prize in 2003 for developing form of low-tech sustainable agriculture:

1. Farmers plant corn in rows in between fast-growing trees at beginning of rainy season

2. Trees cur down before next planting season and leaves are added to soil to add nitrogen

3. Phosphorus added to soil through small rock deposits

4. Farmers place chopped up Mexican sunflower leaves in planting holes to provide micronutrients

12-3 Soil erosion and degradation

• Soil erosion caused primarily by wind, water, and people.

• Preserving world’s top soil = key to feeding world’s growing population.

• Soil is a renewable resource. If it erodes faster than it forms, its nonrenewable.

Soil Erosion

• Movement of soil components, especially surface litter and topsoil from one place to another.

• Two main agents- flowing water and wind.

• Harmful effects:– Loss of soil fertility– Ends up as polluting sediment in nearby surface waters

How serious is global soil erosion? Mostly Bad News

• Topsoil is eroding faster than its being Topsoil is eroding faster than its being formed on 38% of world’s cropland.formed on 38% of world’s cropland.

• Soil erosion and degradation has reduced Soil erosion and degradation has reduced food production on 16% of world’s food production on 16% of world’s cropland.cropland.

• Causes damages of at least $375 billion a Causes damages of at least $375 billion a year.year.

Case Study: soil erosion in the United States today: some hopeful

news

• Many states lost topsoil due to poor cultivation and drought

• Food Security Act (1985) developed strategy for reducing soil erosion

Case Study: the Dust Bowl: An Environmental Lesson from Nature• 1930s – topsoil in mid-western U.S. lost

through drought and poor cultivation

• Large areas of cropland stripped of topsoil

• Triggered large internal migration out of the mid-west.

• Soil Erosion Act (1935) – established soil conservation service which promoted soil conservation.

What is Desertification, and how serious is it? Decreasing Land

Productivity• 1/3 of world’s land has lost productivity

due to drought and human activity that degrade topsoil.

• Deserts have expanded and contracted due to natural climate changes in the past.

• Human activities accelerate desertification.

• 1/3 of world’s land and 70% of drylands is suffering from desertification.

Desertification

• The falling of productive potential of arid or semiarid land by 10% or more

• Due to combination of natural climate change and human activities.

• Can be moderate (10-25% drop in productivity), severe (25-50%), or very severe (50% or more).

How do excess salts and water degrade soils? Crop Losses from

too much salt and water• 1/5 of world’s irrigated cropland produces 40%

of its food.• Irrigation leaves behind a thin crust of dissolved

salts in topsoil.

12-4 Soil ConservationHow can conservation tillage

reduce soil erosion? Do not disturb the soil

• Soil conservation- ways to reduce soil erosion and restore fertility.

• Conventional-tillage farming - land is plowed, broken up, and smoothed to plant.

• Conservation tillage farming – soil is disturbed little

What other methods can reduce soil erosion? Several tried and true

methods• Terracing – Land inverted into level

terraces

• Contour Farming – plowing and planting in rows

• Strip Cropping – planting alternating strips of a row crop

• Alley Cropping – several crops planted together between trees and shrubs

How can we maintain and restore soil fertility? Conservation and

fertilizers• Organic fertilizer from plants and animals

– Types:• Animal manure• Green manure• Compost

• Commercial inorganic fertilizer produced from various minerals

Can Inorganic Fertilizers Save the Soil? A partial solution

• Advantages:– Easy to transport, store, and apply– Inexpensive– Accounts for ¼ of world’s crop yield

• Disadvantages:– Reduces organic matter in soil and ability to hold water– Large amounts of energy to produce, transport, and

apply– Release greenhouse gas, nitrous oxide

12-5: Food production, nutrition, and environmental effects

how much has food production increased? Impressive gains that are slowing how much has food production increased? Impressive gains that are slowing downdown

• World grain production leveled since 80s.

• Per capita food production in decline since 1970s.

• 1 out of 6 people in developing countries are eating enough due to unequal food distribution.

• Hunger and malnutrition caused by poverty and inequality

How serious are Undernutrition and Malnutrition? Some progress

• To maintain health humans need macronutrients and micronutrients

• Chronic undernutrition - people who cannot grow or buy enough food to meet basic needs.

• Malnutrition- from deficiencies of protein and other key nutrients.

• UNICEF trying to stop nutrient-related deaths

• Marasmus – waste away disease, when diet is low in both calories and protein

• Most victims are nursing infants or malnourished mothers and children.

• Kwashiorkor – protein deficiency in infants and children ages 1-3 when you deprive a baby of breast milk. Baby has access to grain but not enough protein

How serious are Micronutrient Deficiencies? Important but limited

progress• 1 out of every 3 people has a deficiencies of

one or more minerals and vitamins• Most widespread micronutrient deficiencies in

developing countries involved vitamin A, iron, and iodine.

How serious is Overnutrition? Bad and getting worst

• Overnutrition - when food energy intake exceeds energy use, resulting in excess body fat.

• Overweight- people 10 to 30 pounds over healthy body weight.

• Obese- if more than 30 pounds over.

• Underfed and overweight and overfed and overweight people face similar problems.

What are the environmental effects of producing food? Agriculture is

number one• Agriculture has a

greater harmful environmental impact than any other human activity

• 30% of world’s cropland has been degraded to some degree by soil erosion.

Case Study: Can China’s population be fed? A precarious

situation• Has 20% of world’s people, 7% of its

cropland and freshwater, 4% of its forests, 2% of its oil.

• Grain production in decline due to water shortages, and degraded cropland.

• Population growth, economic growth, lack of resources and harmful environmental effects of food production may limit crop production.

12-6: Increasing crop productionWhat is the gene revolution?

From cross-breeding to mixing genes in a new way

• Gene Revolution uses genetic engineering to develop genetically improved crops and livestock

• Gene revolution involves splicing a gene from one species and transplanting it into the DNA of another species

• More than 3/4 of US food products are from genetically engineered crops

How Safe are Genetically Modified Foods? Savior or Frankenfood?

• Advantages:– Less fertilizer, water, and

spoilage

– Faster growth and higher yields

– More resistant to insects and disease

– Better flavor

• Disadvantages:– Unpredictable genetic

and ecological effects

– Harmful toxins and new allergens

– Lower nutrition

Can We Continue Expanding the Green Revolution? Maybe, Maybe

Not

• Problems with Green Revolution:– Require large amounts of water and fertilizer– Expensive– Soil erosion lowers crop yields– Overall gains in crop yields may be low– Increased loss of biodiversity

Will People Try New Foods? Changing eating habits is difficult

• Many plants and insects could be used as food sources but most consumers wouldn’t eat them

– Winged bean– Micro-livestock (edible insects)

• Polycultures of perennial crops are better adapted to regional soil and climate conditions

Is Irrigating More Land the Answer? A Limited Solution

• 40% of world’s food production comes from 20% of world’s cropland

• Amount of irrigated land per person in decline

• Reasons– Population growing faster than irrigated agriculture– Depletion of aquifers – Sand buildup in soil

Is Cultivating More Land the Answer? Another limited solution

• Much of land that can be cultivated lies in dry areas

• Expansion of cropland would require dam projects, deplete of water supplies, reduce wildlife habitats, and reduce biodiversity

Can We Grow More Food in Urban Areas? Some Untapped Potential

• Urban gardens provide about 15% of world’s food supply

• Food can be grown in empty lots, backyards, on rooftops and balconies, and in sewage lagoons

• Growing food in urban areas reduces stress on soil and biodiversity

How Much Food is Wasted? Way too much

• 70% of food we produce is lost through 70% of food we produce is lost through spoilage, inefficient processing and spoilage, inefficient processing and preparation, and plate wastepreparation, and plate waste

12-7: Producing more meatHow are rangelands used to produce meat? Grass and shrubs for

livestock

• Rangelands- grasslands in temperate and tropical climates that supply vegetation for grazing and browsing animals.

• Rangeland grass is a renewable resource because their blades grow from the base.

• Moderate levels of grazing are healthy for grasslands.

Is Producing More Meat the Answer? More protein at the expense of the environment

• World meat production increased in last 50 years.

• Future increases in meat production expected to come from feedlots.

• Industrialized approach to meat production increases meat productivity.

• Feedlot production will increase pressure on world’s grain and fish supply.

Some Environmental Consequences of Meat Production

• Meat production uses more than half of water drawn from world’s rivers and aquifers every year

• 14% of US topsoil loss directly associated with feeding livestock

• Livestock waste not all absorbed by soil, running off into bodies of water, killing fish and several endangered species

What are the Health Effects of Overgrazing? Eroding soil and

fewer livestock

• Overgrazing occurs when too many animals graze for too long and exceed carrying capacity of an area.

• Lowers net primary productivity of grass vegetation, reduces grass cover, and can cause desertification.

• Exposes soil to wind and water erosion.

How can rangelands be managed more sustainably to produce more

meat? Control and restore• Control number of grazing animals and

their grazing duration.

• Livestock should be moved from one area to another to help prevent damage of riparian zones (natural water sources).

• Suppress the growth of unwanted invader plants through herbicides or burning.

How can we produce meat more sustainably? Shifting our meat

priorities• Shift from less grain-efficient forms of animal

protein to more grain-efficient ones.• Rangeland is not suitable for growing crops.

12-8: catching and raising more fish and shellfish

Where do we get the fish and shellfish we eat? Oceans and fish farms

• 80% of fish and shellfish we eat comes from ocean or aquaculture

• Fisheries – concentrations of particular aquatic species suitable for commercial harvesting in a given body of water

• Aquaculture – raises animals in feedlots

• 7% of global food is from fish and shellfish

How are Fish and Shellfish Harvested? Hunt and gather as

much as you can

• Trawler Fishing – catches fish on ocean floor

• Purse-seine fishing – catching fish in schools and shallow areas

• Longlining – long lines with thousands of baited hooks

• Drift-net fishing – catching with huge strip-nets

Connections: How are Overfishing and Habitat Degradation Affecting Fish Harvests? Dropping Yields

• Overfishing – the taking of so many fish that too little breeding stock is left to maintain numbers

• Overfishing leads to commercial extinction which is when the population of a species declines to a non-profitable point

• ¾ of marine fish species are overfished

Should Governments Continue Should Governments Continue Subsidizing Fishing Fleets? Too Subsidizing Fishing Fleets? Too many boats chasing too few fishmany boats chasing too few fish

• $120 billion per year to catch $70 billion worth $120 billion per year to catch $70 billion worth of fishof fish

• Government subsidies given to fishing industry Government subsidies given to fishing industry are a major cause of overfishingare a major cause of overfishing

• Without subsidies, fishing boats and fleets Without subsidies, fishing boats and fleets would go out of businesswould go out of business

What is Aquaculture? Feedlots of the sea

• Aquaculture – raising fish and shellfish for food like crops

• Two types:– Fish farming – cultivating fish in a controlled environment

– Fish ranching – holding anadromous species in captivity

• Advantages:– High efficiency of profits

– Reduces overharvesting

• Disadvantages:– Destruction of habitats and fish species

– Contamination and disease

12-9 Government Agricultural Policy

How Do Government Agricultural Policies affect food production? To interfere or not to interfere

• Keeping food prices artificially low makes for happy consumers but unhappy farmers

• Giving farmers subsidies and tax breaks to keep them in business and encourage them to increase food production

• Eliminating all price controls and subsidies and letting farmers respond to market demand without government interference

14-10 Sustainable AgricultureWhat is more sustainable agriculture? Learn from nature

• 3 main ways to reduce hunger:

– Slow population growth– Reduce poverty– Develop sustainable

agriculture

• More sustainable forms of agriculture:

– High yield polyculture– Perennial crops– Crop rotation

• Less Sustainable:– Overgrazing– Overfishing– Loss of prime cropland

How Can We Make the Transition to More Sustainable Agriculture?

Get serious• 4 strategies:

– Increase research on sustainable agriculture– Set up demonstration projects to show how more

sustainable agricultural systems work– Provide subsidies and increase foreign aid– Establish training programs for farmers and

government officials

• Goal: feed the worlds people while sustaining the earth’s natural capital and living off natural income

Alternative Sources

• http://www.ag.auburn.edu/fish/international/polycul.htm

• http://www.geocities.com/gm_crops/• http://marinebio.org/Oceans/OceanResour

ces.asp• http://www.fao.org/desertification/default.a

sp?lang=en• http://www.merck.com/pubs/mmanual_ha/

sec3/ch17/ch17b.html