Agriculture and Land Kraj

Warm-Up SurfaceWater Biomagnification Watershed Smog Groundwater Complete the puzzle using Unit 5 Part 2 Vocab. SurfaceWater Biomagnification Watershed Smog Groundwater AcidPrecipitation Aquifer pH RechargeZone Famine Reservoir Malnutrition Desalination Compost PointSourcePollution GeneticEngineering Wastewater

Humans and Nutrition Famine is widespread malnutrition and starvation in an area due to a shortage of food, usually caused by a catastrophic event. Malnutrition is a disorder of nutrition that results when a person does not consume enough of the nutrients that are needed by his or her body.

Sources of Nutrition Diet is the type and amount of food that a person eats. A healthy diet is one that maintains a balance of the right amounts of nutrients, minerals, and vitamins. The foods produced in the greatest amounts worldwide are grains, plants of the grass family whose seeds are rich in carbohydrates. People in more developed countries tend to eat more food and a larger proportion of proteins and fats than people in less developed countries.

Food Efficiency The efficiency of a given type of agriculture is a measure of the quantity of food produced on a given area of land with limited inputs of energy and resources. An ideal food crop is one that efficiently produces a large amount of food with little negative impact on the environment.

World Food Problems Some people become malnourished because they simply do not get enough food. More food is needed each year to feed the world’s growing population. World food production has been increasing for decades, but now food production is not increasing as fast as the human population is increasing.

Unequal Distribution If all the food in the world today was divided equally among the human population, no one would have quite enough food for good health. But food is not divided equally, and malnutrition is largely the result of poverty. Even in the United States, many poor people suffer from malnutrition. Wars and political strife can also lead to malnutrition because they interrupt transportation systems.

Droughts and Famines A drought is a prolonged period during which rainfall is below average, and crops grown without irrigation may produce low yields or fail entirely. A drought is more likely to cause famine in places where most food is grown locally. If a drought occurs, there may be no seed to plant crops the following year. The effects of a drought can continue for years.

The Green Revolution Worldwide, between 1950 and 1970, increases in crop yields resulted from the use of new crop varieties and the application of modern agriculture techniques. These changes were called the green revolution. Since the 1950s, the green revolution has changed the lives of millions of people. However, the green revolution also had some negative effects.

The Green Revolution For example, most new varieties of grain produce large yields only if they receive large amounts of water, fertilizer, and pesticides. In addition, the machinery, irrigation, and chemicals required by new crop varieties can degrade the soil if they are not used properly. As a result of the overuse of fertilizers and pesticides, yields from green revolution crops are falling. The grain production in the U.S. has decreased since 1990, partly because the amount of water used for irrigation has decreased.

The Green Revolution In addition, the green revolution had a negative impact on subsistence farmers, or farmers who grow only enough food for local use. Before the green revolution, subsistence farmers worked most of the world’s farms. But they could not afford the equipment, water, and chemicals needed to grow new crop varieties.

Enriching the Soil A modern method of enhancing the soil is to use both organic and inorganic materials by adding compost and chemical fertilizers to the soil. Compost is a mixture of decomposing organic matter, such as manure and rotting plants, used as fertilizer and soil conditioner. Many cities and industries now compost yard and crop wastes. This compost is then sold to farmers and gardeners, saving costly landfill space.

Salinization The accumulation of salts in the soil is known as salinization. Salinization is a major problem in places that have low rainfall and naturally salty soil. When water evaporates from irrigated land, salts are left behind. Salinization can be slowed if irrigation canals are lined to prevent water from seeping into the soil, or if the soil is watered heavily to wash out salts.

Pest Control Worldwide, pests destroy about one-third of the world’s potential food harvest. A pest is any organism that occurs where it is not wanted or that occurs in large enough numbers to cause economic damage. Humans try to control populations of many types of pests, including plants, fungi, insects, and microorganisms.

Pesticides Many farmers rely on pesticides to produce their crops. A pesticide is a poison used to destroy pests, such as insects, rodents, or weeds; examples include insecticides, rodenticides, and herbicides. Pesticides, however, can also harm beneficial plants, insects, wildlife, and even people. Pest populations may evolve resistance, the ability to survive exposure to a particular pesticide.

Human Health Concerns Pesticides are designed to kill organisms, so they may also be dangerous to humans. Cancer rates among children in areas where large amounts of pesticides are used on crops are sometimes higher than the national average. People who apply pesticides need to follow safety guidelines to protect themselves from contact with these chemicals.

Engineering a Better Crop Genetic engineering is a technology in which the genome of a living cell is modified for medical or industrial use. Scientists may use genetic engineering to transfer desirable traits, such as resistance to certain pests, from one organism to another. Plants that result from genetic engineering are called genetically modified organisms (GMOs).

Engineering a Better Crop

Implications of Genetic Engineering In the United States, we now eat and use genetically engineered agricultural products every day. Many of these products, however, have not been fully tested for their environmental impacts. Some scientists warn that these products will cause problems in the future.

Overharvesting Overharvesting is the catching or removing more organisms from a population than the population can replace. Many governments are now trying to stop overharvesting. For example, they have created no-fishing zones so that fish populations can recover.

Aquaculture Aquaculture is the raising of aquatic plants and animals for human use or consumption. Fish and other aquatic organisms provide up to 20 percent of the animal protein consumed worldwide. Aquaculture may be one solution to the overharvesting of fish and other organisms in the world’s oceans.

Livestock Livestock is the term given to domesticated animals that are raised to be used on a farm or ranch or to be sold for profit. Populations of livestock have changed dramatically in the last 40 years. Large livestock operations produce most of the meat that is consumed in developed countries.

Ruminants Ruminants are cud-chewing mammals that have a three- or four-chambered stomach. Cattle, sheep, and goats are examples of ruminants. Cud is the food that these animals regurgitate from the first chamber of their stomachs and chew again to aid digestion. When we eat the meat of ruminants, we are using them to convert plant material, such as grass stems and woody shrubs, into food that we can digest—such as beef.