Land and Land Resources

Land and Land Resources Chapter 12

UNIT 8“If we can't afford to take good care

of the land that feeds us, we're in an insurmountable mess.”

-Wendell Berry

Food, Soil, and Pest ManagementNotes from Chapter 12 in Living in the Environment

Chapter Summary

1. Even though food production has lev-eled off in the last 25 years, the world still produces enough food to meet the basic nutritional needs of people. However, the food cannot be evenly distributed through-out the world, leading to malnutrition and starvation. Many of these deaths come from malnutrition, which leads to a lack of resistance to diseases. Modern agricultural techniques create significant environ-

mental harm, but the green revolution is also responsible for large increases in agri-cultural productivity.

2. Three systems produce foods for hu-man consumption. Croplands produce mostly grains, about 77% of the world’s food. Rangelands provide meat, about 16% of the world’s food. Ocean fisheries supply about 7% of the world’s food.

3. Soils are degraded and eroded by wa-ter, wind, and people. Soil erosion is pri-

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marily caused by flowing water and wind. Human activities, such as farming, logging, construction, off-road vehicles, etc., also disturb soil and hasten erosion. In much soil there is also salt buildup and waterlog-ging. Crops can be planted today with less soil disturbance through conservation-tillage, tillage, contour farming, and strip farming. Farmers may also use cover crops to help hold the soil in place. Several crops planted between trees and shrubs, alley cropping, help preserve soil and its productivity. And windbreaks are used to prevent soil from being blown away. Con-servation and fertilization can be used to restore soil fertility, but fertilizing with com-mercial pesticides brings its own set of problems.

4. The green revolution uses particular methods to raise crops. Monocultures are developed and planted, bred selectively, or genetically engineered to produce high yields of particular crops. Large amounts of fertilizer, pesticides, and water are added to the crops. Yields of crops are in-creased through multiple cropping through-out the year. The second green revolution since 1967 involved using fast-growing dwarf varieties of wheat and rice in coun-tries with tropical and subtropical climates. Traditional agriculture: uses interplanting, several crops grown together on the same

area of land; uses agroforestry, which grows crops and trees together; and ap-plies polyculture, where various plants are planted together but mature at different times.

5. Food production can be increased by using crossbreeding techniques on similar organisms and using genetic engineering on different organisms. Genetic engineer-ing, including using advanced tissue cul-ture techniques, is growing in use; but many people are concerned about the po-tential harm such crops may cause. Irrigat-ing more land and cultivating more land are additional solutions but they may not prove sustainable. Rangelands can be managed more efficiently, with the land area better protected; but a meat-based diet requires substantially more resources than a plant-based diet. Overfishing and habitat degradation dominate the marine environment; better management of this food source and protection of the marine environment would ensure continued avail-ability of fish worldwide.

6. More sustainable agricultural systems can be created by reducing resource throughput and working with nature. Tech-nologies based on ecological knowledge are used to increase crop production, to control pests, and to build soil fertility.

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Such low-input organic farming is often more friendly to the environment by using less energy than conventional farming de-mands, and by improving soil fertility. Low-input organic farming is also more profit-able for farmers.

7. Pesticides are chemicals that kill or control populations of organisms we con-sider undesirable. Types include insecti-cides, herbicides, fungicides, and rodenti-cides. The advantages of using pesticides include the fact that they save lives, in-crease food supplies, lower food cost, in-crease profit for farmers, and work fast. The disadvantages include the accelera-tion of pest resistance to pesticides and pesticides dispersing widely, harming wild-life, and threatening human lives. The Fed-eral Insecticide, Fungicide, and Rodenti-cide Act established in 1947 and amended in 1972, as well as the 1996 Food Quality Protection Act regulate pesticide use in the United States. Alternatives to pesticides in-clude integrated pest management, cultiva-tion practices, food irradiation, genetic en-gineering, biological control, hot water, and pheromones. These all reduce pesticide use but may prove timely, costly, and not as reliable.

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12-1: What Is Food Security and Why Is It Diffi-cult to Obtain?

CORE CASE STUDY: Organic agriculture is a component of sustainable agriculture in which crops are grown without synthetic pesticides, synthetic inorganic pesticides and genetically modified seeds. Between 2002 and 2008 the global market for or-ganic food doubled, however, it is only practiced on less than 1% of the world’s farmland. Organic farming has a number of environmental advantages over conven-tional agriculture, though the latter gener-ally leads to higher yields.

A. Food security means that all or most people in a country have daily access to enough food to be healthy and active.

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Starving Children in Sudan Collect Ants

1. Global food production has stayed ahead of population growth, but one in six people in developing countries cannot grow or buy the food they need (face food insecurity).

B. The root cause of food insecurity is poverty.

1. Other obstacles include political up-heaval, war, corruption, and drought or other prolonged weather conditions.

2. It is projected that by the end of the century there is a greater than 90% chance that half of the world’s population will face food shortages due to climate change.

C. People need fairly large amounts of macronutrients (protein, carbohydrates, fats) and smaller amounts of micronutri-ents (vitamins such as A, C, E) and min-erals (iron, iodine, calcium).

1. Chronic undernutrition, or hunger, is when people do not have access to enough food to meet basic energy needs.

2. Chronic malnutrition occurs when there is a deficiency of protein or other key nutrients.

3. Famine occurs when there is a se-vere shortage of food in an area that re-sults in mass starvation.

D. One in three people has a deficiency of one or more vitamins and minerals, es-pecially vitamin A, iron, and iodine.

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This woman in Bangladesh has a goiter, an enlargement of the thyroid gland caused by a diet containing too lit-tle iodine.

E. In the developed world, the problem is overnutrition, which leads to obesity, re-duced life quality, poor health, and prema-ture death.

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12-2 How is Food Produced?

A. Food production from croplands, rangelands, ocean fisheries, and aquacul-ture has increased dramatically.

B. Wheat, rice, and corn provide more than half of the calories in the food con-sumed by the world’s people.

C. About 80% of the world’s food supply is produced by industrialized agriculture.

1. Plantation agriculture is a form of industrialized agriculture that involves pro-ducing cash crops.

2. Increasingly industrialized agricul-ture is relying on greenhouses.

CASE STUDY: Hydroponics involves grow-ing plants in nutrient solutions instead of soil. The advantages over conventional systems are the crops can be grown in-doors, yields are increased, crops can be grown on rooftops, fertilizer and water use

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These salad greens are being grown hydroponically (with-out soil) in a greenhouse. The plant roots are immersed in a trough and exposed to nutrients dissolved in running wa-ter that can be reused.

are reduced, and there is little or no need for pesticides if crops are grown in a con-trolled environment. Three main draw-backs are that it takes a large investment to get started, many fear that is requires too much technical knowledge, and it could threaten the profits of companies that produce chemicals and farm equip-ment.

D. Many farmers in developing countries use traditional agriculture to grow a variety of crops on each plot of land.

1. Traditional subsistence agriculture uses labor and draft animals to supply food for a family, with little left over.

2. Traditional intensive agriculture in-volves increased inputs of fertilizer and wa-ter to obtain higher crop yields.

3. Polyculture involves growing several crops simultaneously.

4. Slash and burn agriculture is subsis-tence agriculture that burning and clearing small plots of tropical forest on a rotational basis.

E. The large increases in crop production over the last half of the 20th century are the result of the green revolution. This in-cludes selective breeding of crops, use of

fertilizers, pesticides and irrigation, and multiple cropping systems.

SCIENCE FOCUS: Soil is a complex mix of rock, nutrients, organic material, air, water, and living organisms. Although top-soil is a renewable resource, it is renewed very slowly.

Layers (horizons) of mature soils

O horizon: leaf litter

A horizon: topsoil

B horizon: subsoil

C horizon: parent material, often bedrock

CASE STUDY: Food production in the US is characterized by agribusiness, with a small number of multinational companies controlling food production and distribu-tion. As a result Americans spend only a very small portion of their income on food, but are typically not aware of the hidden

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costs, such as environmental costs and taxes for subsidies.

A. Traditionally, farmers have relied on crossbreeding through artificial selection to develop improved varieties. Today ge-netic engineering is used to develop im-proved strains.

1. Genetically modified organisms are planted on about 12% of the world’s crop-land.

2. More than 80% of the corn, soybeans and cotton grown in the US are genetically engineered.

G. Between 1961 and 2007 world meat production has increased more than four-fold and per capita consumption has dou-bled.

1. About half the world’s meat comes from rangelands and pastures. The other half is raised on crowded feedlots and in concentrated animal feeding operations (CAFO’s).

2. As a country’s income grows, people tend to eat more meat.

H. A fishery is a concentration of a particu-lar aquatic species suitable for commercial harvest. Aquaculture is the process of rais-ing fish in ponds or enclosures.

1. At least 63% of ocean fisheries are de-pleted or overexploited.

2. Aquaculture is the world’s fastest growing type of food production.

I. Industrial food production is heavily reli-ant on the availability of energy, primarily oil and natural gas.

1. It takes about 10 units of nonrenew-able energy to put 1 unit of food energy on the table.

These graphs show that worldwide grain produc-tion of wheat, corn, and rice (left), and per capita grain production (right) grew sharply between 1961 and 2009. The world’s three largest grain-producing countries—China, India, and the United States, in that order—produce almost half of the world’s grains. In contrast to the United States, most wheat produced in China and India is irri-gated.

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12-3 What Environmental Problems Arise from Food Production?

A. Soil erosion lowers soil fertility and can overload nearby bodies of water with eroded sediment. Soil is eroding faster

than it is forming on more than one-third of the world’s cropland.

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Flowing water from rainfall is the leading cause of topsoil ero-sion as seen on this farm in the U.S. state of Tennessee.

Topsoil erosion is a serious problem in some parts of the world. In 2008, the Chinese government estimated that one-third of China’s land suffers from serious topsoil erosion.

B. About one-third of the world’s land has lower productivity because of drought and human activities that reduce or de-grade topsoil.

C. Desertification occurs when the pro-ductive potential of topsoil falls by 10% or more.

1. 70% of the world’s drylands used for agriculture are threatened by desertifi-cation.

Severe desertification: Sand dunes threaten to take over an oasis in the Sahel region of West Africa. Such severe deserti-fication is the result of prolonged drought from natural cli-mate change and destruction of natural vegetation as a re-sult of human activities such as farming and overgrazing.

D. Repeated irrigation can reduce crop yields by causing salt buildup in the soil (salinization-pictured below) and water-logging of croplands.

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E. Agricultural activities produce signifi-cant amounts of air pollution

1. Industrialized livestock production ac-counts for more greenhouse gasses than all of the world’s cars, busses, and planes emit (18%).

F. Crops grown for biofuels production are expanding, particularly in tropical zones, leading to losses of agrobiodiver-sity.

1. Since 1900, roughly ¾ of the genetic diversity of agricultural crops have been lost.

2. Crop varieties are now stored in gene banks, agricultural research centers, and botanical gardens around the world.

G. New genetically modified food crops could have unintended negative ecologi-cal consequences.

H. Meat production systems have numer-ous environmental impacts. They use huge amounts of energy, produce a lot of waste, pollute groundwater, lead to erosion and degradation of rangelands. Another concern is the widespread use of antibiotics.

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I. Aquaculture now accounts for roughly half of global seafood production.

1. Advantages include high efficiency, high yield, reduced overharvesting of fisher-ies, low fuel use, and high profits.

2. Disadvantages include large inputs of feed and water, large waste output, loss of habitat, some species are fed fish meal, and dense populations can be vulnerable to disease.

World Seafood Production, Including Both Wild Catch and Aquaculture

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12-4 How Can We Protect Crops from Pests More Sustainably?

A. Organisms found in nature control populations of most pest species as part of the earth’s free ecological services.

B. We use chemicals to repel or kill pest organisms as plants have done for millions of years. To help control pest organisms we have developed a variety of pesticides.

C. Pesticide use has increased 50-fold and toxicity has increase 10–100 times. Many pesticides are persistent in the envi-

ronment and have significant impacts on human and animal health.

D. Modern pesticides save lives, in-crease food supplies, increase profits for farmers, and are fast acting.

E. Pesticides do not work forever, as pest species evolve resistance to particu-lar chemicals (coevolution).

F. Pesticides can promote genetic resis-tance to their effects, wipe out natural ene-

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Spiders are important insect predators that are killed by some pesticides. Most spi-ders, including this ferocious-looking wolf spider, do not harm humans.

mies of pest species, create new pest spe-cies, end up in the environment, and some-times harm wildlife and people.

G. Pesticides have not reduced crop loss overall.

CASE STUDY: There are many unintended effects of pesticide use. An example comes from a program directed at ridding North Borneo of malaria in the 1950’s. It was successful, but soon other insects be-gan to disappear, then the lizards that fed on them, and finally the cats that fed on the lizards. In the absence of cats, rats flourished and the people became threat-ened by sylvatic plague.

H. In the US the Food and Drug Admin-istration (FDA), the Department of Agricul-ture (USDA) and the Environmental Protec-tion Agency (EPA) regulate the sale and use of pesticides under the Federal Insecti-

cide, Fungicide and Rodenticide Act (FI-FRA).

1. Less than 10% of the active ingredi-ents in pesticides have been tested for health effects.

I. There are cultivation, biological, and ecological alternatives to conventional chemical pesticides. A number of methods are available.

1. Fool the pest using cultivation prac-tices such as crop rotation.

2. Provide homes for pest enemies.

3. Implant genetic resistance.

4. Bring in natural enemies.

5. Use insect pheromones to lure pest insects into traps or to lure natural preda-tors to crop fields.

6. Use hormones that disrupt the normal insect life cycle and prevent them from reaching maturity. The disadvantages are that they take weeks to kill an insect, are often ineffective if the infestation is large, and must be applied at the right time in the life cycle.

Integrated pest management (IPM) is an ecological approach to pest control that

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uses a mix of cultivation and biological methods, and small amounts of selected chemical pesticides as a last resort.

Biologist Rachel Carson (1907–1964) greatly in-creased our understand-ing of the importance of nature and of the harmful effects of the widespread use of pesticides.

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12-5 How Can We Improve Food Security?

A. Governments use policies to influ-ence food production.

1. Control prices.

2. Provide subsidies.

B. Simple and relatively inexpensive ac-tions can have large impacts. One-half to two-thirds of nutrition-related childhood death could be prevented for $5–10 per child per year.

1. Provide immunization.

2. Prevent dehydration.

3. Prevent blindness with a vitamin A capsule twice a year.

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12-6 How Can We Produce Food More Sus-tainably?

A. Sustainable agriculture through soil conservation—Soil conservation seeks ways to reduce soil erosion and restore soil fertility, mostly by keeping the soil cov-ered with vegetation. Some additional methods include terracing,

contour

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planting, strip cropping, agroforestry and the use of windbreaks.

CASE STUDY: Soil erosion in the United States during the dust bowl years lead to dramatic changes in agricultural policy.

B. Restore soil fertility using organic fertiliz-ers, reduce soil salinization and desertifi-cation, and use sustainable aquaculture techniques.

C. Eat lower on the food chain and slow population growth.

CASE STUDY: The largest salmon producer in Canada has turned toward sus-tainable aquaculture by mimicking a natu-ral ecosystem.

D. Meat production is highly inefficient and could be improved by shifting toward more grain-efficient forms of animal pro-tein, such as poultry and plant eating fish as well as by reducing meat consumption.

E. Five strategies to make the transition to a more sustainable agriculture:

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1. Increase research

2. Establish training programs

3. Set up an international fund to give farmers in poor countries access to sus-tainable agriculture

4. Establish subsidies that encourage sustainable agriculture

5. Mount a massive education program

SCIENCE FOCUS: Perennial polycul-tures have many advantages, including no tilling requirement, reduced erosion, less irrigation, and less chemical fertilizers.

F. Sourcing food locally is an important component of sustainable food produc-tion.

1. Community Supported Agriculture (CSA) and farmer’s markets provide this.

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