Agriculture is the art and science of cultivating the soil, growing crops and raising livestock. It includes preparing plant and animal products for people to use and sell.

Agriculture provides most of the world's food and fabrics. Cotton, wool and leather are all agricultural products. Agriculture also provides material for construction and paper.

Start of Agriculture

Over the centuries, agriculture contributed to the rise of civilizations.

Before agriculture became widespread, people spent most of their lives searching for food. They hunted for wild animals and gathered wild plants. About 11,000 years ago, people began learning how to grow grains and roots, and they settled down to a life based on farming.

By 2,000 years ago, much of Earth's population depended on agriculture. When people began growing crops, they also began raising wild animals. Adapting wild plants and animals for people to use is called domestication.

The first domesticated plant was probably rice or corn. Chinese farmers were cultivating rice as early as 7500 B.C.

The first domesticated animals were dogs, which were used for hunting. Sheep and goats were probably domesticated next, and then cattle and pigs. Most of these animals had once been hunted for hides and meat. Now many of them also became sources of milk, cheese and butter. Eventually, people used domesticated animals such as oxen for plowing, pulling and transportation.

Agriculture enabled people to produce extra food to trade or to use when crops failed. Food surpluses also meant that people did not have to spend all their time growing food.

Previously, humans were nomadic, meaning they would move from place to place. With agriculture, certain societies started building permanent villages. These villages traded goods with each other and became more developed. Some areas were so successful that cities grew and entire civilizations took shape. The earliest agricultural civilizations started near the Tigris and Euphrates rivers in Mesopotamia, now Iraq and Iran, and along the Nile River in Egypt.

Improved Technology

The development of agriculture was very slow for a long period of time. One of the earliest agricultural tools was fire. Native Americans used fire to control the growth of plants, which grew quickly after a wildfire. Farmers cultivated small plots of land by hand, using axes to clear away trees and digging sticks to break up and till the soil. Over time, better farming tools developed, as well as ways to store food. People began making clay pots and other vessels for carrying and cooking food.

Around 5500 B.C., farmers in Mesopotamia developed simple irrigation systems. They were able to channel water from streams to their fields and settle in areas that were too dry.

Early farmers also developed improved varieties of plants. For example, about 6000 B.C., a new variety of wheat was developed in South Asia and Egypt. It was stronger than other grains and it was used to make bread.

New techniques of cultivation developed over thousands of years. For example, medieval European farmers used an open-field system of planting. One field would be planted in spring, another in autumn, and one would be left unplanted, or fallow. This system preserved nutrients in the soil, letting farmers produce more crops.

In the 1400s and 1500s, explorers brought new varieties of plants and agricultural products into Europe. From Asia, they carried home coffee, tea and indigo, a plant used to make blue dye. From the Americas, they took plants such as potatoes, tomatoes, corn, beans, peanuts and tobacco.

Machinery

A period of important agricultural development began in the early 1700s. One of the most important inventions was a seed drill created by Jethro Tull in England. Until that time, farmers sowed seeds by hand. Tull's drill made rows of holes for the seeds and made the process quicker.

Many machines were developed in the United States. The cotton gin, invented by Eli Whitney in 1794, reduced the time needed to separate cotton fiber from seed. John Deere's steel plow, introduced in 1837, made it possible to work the tough prairie soil with less horsepower.

Along with new machines, there were several important advances in farming methods. Farmers began breeding animals with desirable traits and increased the size of their livestock.

Agricultural Science

In the early 1900s, an average farmer in the U.S. produced enough food to feed a family of five. Many of today's farmers can feed that family and about 100 other people. This great leap in productivity came about because of scientific advances and new sources of power.

By the late 1950s, most farmers in developed countries were using both gasoline and electricity to power machinery. Tractors replaced draft animals and steam-powered machinery. By 1960, most farms in the U.S. and other developed countries were electrified. Electricity lit farm buildings and powered machines such as water pumps, milking machines and feeding equipment.

Chemistry also helped the development of agriculture. For thousands of years, farmers had relied on natural fertilizers. They used manure, wood ash, ground bones, fish or fish parts, and bird and bat waste called guano. In the early 1800s, scientists discovered that nitrogen, phosphorus and potassium were most important for growing plants. Later, fertilizer containing these elements was manufactured in the U.S. and in Europe.

Now, almost all farmers rely on chemicals to control pests. With the use of chemicals, crops have higher yields and food is much cheaper. However, pesticides and fertilizers tend to disturb the environment as well. They often destroy helpful species of animals along with harmful ones.

Farming in Water

Agriculture does not happen only on land. Hydroponics is the science of growing plants in vats of nutrients. Just one acre can yield more than 50 times the amount of lettuce as the same amount of soil.

Another technique, called aquaculture, is the cultivation of fish and shellfish. It has been practiced in China, India and Egypt for thousands of years and is now used throughout the world. However, climate change and improved technology are changing the way freshwater and ocean fisheries operate. Global warming has pushed warm-water species toward the poles and reduced the habitats of cold-water species. Traditional fishing communities find the number of fish dwindling.

Genetic Modification

For centuries, people have created new types of plants and animals through experimentation. During the 1950s and 1960s, scientists created types of wheat and rice that were easier to grow, then introduced them into Mexico and parts of Asia. As a result, production of grain soared in these areas. This bold experiment in agriculture has been called the "Green Revolution."

These new plans required chemical fertilizers and pesticides. In less developed areas, farmers couldn't afford them and big businesses took over farming. Rain forests and other natural areas were destroyed to grow crops.

Then came the genetic modification of food. Genes contain the instructions for how each part of a plant or animal grows and works. Beginning in the 1970s, scientists found that they could rearrange genes and add new ones. They could make a crop resistant to disease or increase productivity.

Genetically modified organisms are also called GMOs or GM foods. A gene from an Arctic plant, for example, could be added to a strawberry plant. It will increase the strawberry's resistance to cold and farmers can grow the plant longer into the season.

The controversies surrounding GM foods are enormous. Farmers who grow GM foods can produce more with less labor and less land. Vegetables and fruits last longer and are less likely to bruise. However, critics argue that GM foods aren't as healthy. The organic and "free-range" food industries have grown in opposition to GMOs.

Most of the world's farmers live in developing countries in Africa, Asia and Latin America. Many of them cultivate land as their ancestors did. These people are subsistence farmers. They use most of the food they produce for themselves and their families, unlike commercial farmers, who grow crops only to sell.

Methods of Cultivation

There are still many differences between farming techniques around the world. Low-technology farming involves permanent crops, such as fruit trees. In higher-technology farming, crops are planted according to the season, type of soil and the amount of water needed.

Farmers in coastal West Africa, usually women, plant corn soon after the first rains. Between rows of corn, the African farmer plants other crops like legumes, such as peas, or root vegetables, such as yams. This practice of growing different crops together is called intercropping. Rain supplies water for the growing plants. Farmers use hoes to get rid of weeds in their plot. At harvest time, farmers and their families pick the corn, husk it and spread the ears in the sun to dry. They grind the dried corn to make porridge.

Agricultural methods used in the U.S. Corn Belt are very different. The Corn Belt is in the Midwest, where most of the nation's corn is grown. First of all, farmers rarely work alone because the size of American farms requires a great deal of labor. A planter pulled by a tractor sows rows of seed. The machine makes furrows in the soil, drops in kernels of genetically modified corn, and covers them with dirt. After the corn seeds have sprouted, another machine injects liquid fertilizer into the ground. The farmers then use chemicals to control weeds and pests.

U.S. industrial farmers might plant a thousand acres of just corn. To harvest the crop, farmers use a mechanical harvester that picks the ears of corn. Most of the corn grown in the U.S. is used for cattle feed and industrial products, such as sweeteners.

Livestock

Agriculture also involves breeding and raising animals. From alpacas in Peru to zebu cattle in India, people raise billions of domesticated animals around the world. In Nigeria, for example, the Fulani people move with their cattle herds from one grazing area to another. The cattle feed on scrub and grasses in land unsuitable for farming. The Fulani rely on cattle for milk but rarely kill their animals for meat.

Throughout the U.S., beef cattle are bred to grow quickly and yield large quantities of meat. Many farmers throughout the world practice free-range poultry farming. The birds forage for food, eating whatever they find: seeds, insects, household scraps and surplus grain.

In many developed countries, poultry production has become a major industry. Birds are given the same sort of vaccines and hormones used for cattle. One poultry house might contain more than a million birds. Often, machines automatically provide feed and water, collect the eggs and remove waste.

Fight Against Hunger

Food production must keep up with a growing population. Many countries are not able to produce enough food, while droughts, floods and other disasters continue to cause local food shortages. Overpopulation might also contribute to hunger. Over the next 100 years, much of the population increase will occur in developing countries, where hunger is already a serious problem.

Countries that are able to produce more food are exporting it to areas in need. Yet, this will not solve the problem of world hunger. Poor countries do not have the money to buy all the required food. They also do not want to permanently rely on other countries.

Scientists are working to solve this problem. For example, they are developing new types of crops that require fewer fertilizers or pesticides. This would make food production cheaper.

At the same time, the world's land and water must be protected. Many countries need better programs for replanting forests. Demand for food has led to increased irrigation, which, in some areas, has caused rivers to run dry and wells to go empty.

Agricultural chemicals often contaminate soil and groundwater. Yet, agriculture does not have to harm the environment. By protecting the land, water and air, and by sharing knowledge and resources, people may find solutions for world hunger.