• Grain is the harvested seed of grasses such as wheat, oats, rice, and corn. Other important grains include sorghum, millet, rye, and barley. Around the globe, grains, also called cereals, are the most important staple food. Humans get an average of 48 percent of their calories, or food energy, from grains. Grains are also used to feed livestock and to manufacture some cooking oils, fuels, cosmetics, and alcohols.

    Almost half of the grains grown around the world are harvested for people to eat directly. People turn wheat flour into bread, steam rice, and make corn tortillas. Grains are a food staple in almost every culture on Earth. A food staple is food that is eaten frequently, often at every meal. Staple foods can be eaten fresh or stored for use all year. Rice, corn, and wheat are the most common staple foods on Earth.

    Grains are so important because they are a good source of important nutrients called carbohydrates. Carbohydrates are a type of sugar that provides energy for organisms to function. Grains have carbohydrates as well as other important nutrients, such as vitamins. While grains fill many nutritional needs, they often lack some important proteins. In many cultures, grains are part of a staple diet when combined with protein-rich legumes, such as beans. Together, grains and legumes make a healthy diet: corn and beans, rice and tofu, wheat bread and peanut butter.

    A third of the world’s grain supply is fed to animals. Most domestic animals, from cattle to dogs, are fed food rich in grains and grain products.

    The rest of the world’s grain supply is used in the manufacture of industrial products. Biodiesel is a fuel used for vehicles. One type of biodiesel is ethanol, which can be made from corn.

    Grains are annual plants. This means they have only one growing season per year, yielding one crop. Every growing season, grasses grow, reach maturity, produce seeds, and then die. Grains are harvested from dead, or dry, grasses.

    Some grains are winter grains, such as rye. They are able to withstand cold, wet climates. Others are summer grains, such as corn. Corn usually grows best in warm weather.

    Grains can grow in almost any climate. Rice is the most important grain in many tropical areas, where it is hot and humid year-round. Rice is especially common in Asia. In Southeast Asia, rice is grown and harvested in flooded fields called paddies. Rice paddies can be flat or terraced. Terraced rice paddies look like steps on a green hill. This type of grain agriculture has been used for centuries.

    Unlike rice, sorghum does not grow well in a wet climate. Sorghum favors an arid climate. The nations of West Africa, including Senegal, the Gambia, Burkina Faso, and Cape Verde, are the world’s largest producers of sorghum.

    In temperate areas—those with warm summers and cold winters—wheat is the most common grain. Wheat fields are common in the Great Plains of the United States and Canada, for instance. Corn, which is native to the Americas, is now grown in many temperate areas throughout the world. Oats, another grain that grows in temperate areas, are also used as a livestock feed.

    Harvesting Grain

    People first began eating grains about 75,000 years ago in western Asia. These grains, including einkorn and emmer, were ancestors of today’s wheat. Einkorn and emmer grew wild near the banks of rivers. People harvested the grasses that grew naturally near their communities.

    People began cultivating, or growing, grain more recently. In 2009, scientists announced that they had discovered the world’s oldest known grain silos at Dhra in what is now the nation of Jordan. The silos, which date back 11,000 years, contained remnants of barley and an early type of wheat. 

    Ancient people ate grains in much the same way we do today. Wheat grains were made into flour and used in breads. Rice was steamed and eaten hot or cold. Oats were mashed with water or milk to make oatmeal. Beer, one of the oldest manufactured beverages in the world, is made from grain such as barley. Ancient beers had a very low alcohol content, but were good sources of carbohydrates.

    In some ancient civilizations, grain products served as wages or forms of currency. Many of the workers who built Egypt’s pyramids at Giza, for instance, were often paid in bread and beer.

    Today, grain silos are a familiar sight to many people in the developed world. Harvesting is done almost entirely with enormous, expensive machinery. The most important piece of agricultural machinery for grain crops is the combine harvester. This remarkable machine does three jobs: it cuts the grain, threshes the grain, and winnows the grain. Cutting, of course, is removing the grain from the stalk of grass. Threshing is loosening the edible grain from its casing, called the chaff. (Chaff is inedible; organisms cannot digest it.) Winnowing is the process of removing the grain from the chaff. Combine harvesters help farmers expand the amount of grains they can harvest by combining three activities into one.

    In the developing world, few farmers have the huge fields of grain that agribusinesses in the developed world do. Farmers in the developing world typically have a few acres, and provide grain for their local community. These farmers usually thresh and winnow with separate machines (threshers and winnowers) after harvesting the field. In many places, harvesting is still done with hand tools such as the sickle, a long, curved blade used for cutting many stalks of grain at once.

    Whole grains are cereals that have not been processed to remove their natural tissues: germ (the seed's embryo), endosperm (nutrition for the embryo), and bran (outer layer).

    Rice is Life
    Rice is a staple food in much of Asia. The average person eats it two or three times a day. In Myanmar, the average person eats 195 kilograms (430 pounds) of rice each year. That's a lot more than the average American, who eats just 7 kilograms (15 pounds) or the average European, who eats only 3 kilograms (7 pounds).

    In most countries, the grain of the Zea mays plant is called maize. In the United States, it's called corn.

    Grain Elevator
    A grain elevator is just what it sounds like. It's a large storage facility for grain that is equipped with lifting mechanisms, so large amounts of grain can be lifted and poured into trucks, railroad cars, or other storage facilities.

    A grain (gr) is a unit of measurement based on the mass of a typical grain, such as wheat. A grain is 64.8 milligrams.

  • Term Part of Speech Definition Encyclopedic Entry
    acre Noun

    unit of measure equal to .4 hectares.

    agribusiness Noun

    the strategy of applying profit-making practices to the operation of farms and ranches.

    agriculture Noun

    the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).

    Encyclopedic Entry: agriculture
    alcohol Noun

    chemical compound, usually ethanol or methanol, generated by fermentation and used for fuel, hygiene, medicine, and food.

    ancestor Noun

    organism from whom one is descended.

    ancient Adjective

    very old.

    annual Adjective


    arid Adjective


    bank Noun

    a slope of land adjoining a body of water, or a large elevated area of the sea floor.

    barley Noun

    grass cultivated as a grain.

    bean Noun

    edible seed of legumes.

    beer Noun

    alcoholic beverage made from grain.

    beverage Noun

    liquid for drinking.

    biodiesel Noun

    fuel made at least partly from renewable sources such as soy oil, palm oil, or animal fats.

    calorie Noun

    unit of energy from food, equal to the amount of heat required to raise the temperature of one kilogram of water by one degree Celsius.

    carbohydrate Noun

    type of sugar that is an important nutrient for most organisms.

    casing Noun

    material on the outside of a substance, usually there to protect the material inside.

    cattle Noun

    cows and oxen.

    cereal Noun

    type of grain, including wheat.

    chaff Noun

    the dry, usually worthless, husks of grain or grass.

    civilization Noun

    complex way of life that developed as humans began to develop urban settlements.

    Encyclopedic Entry: civilization
    climate Noun

    all weather conditions for a given location over a period of time.

    Encyclopedic Entry: climate
    combine harvester Noun

    farm machine that cuts, threshes, and winnows grain.

    cooking oil Noun

    liquid fat taken from plants such as olives and soy. Also called vegetable oil.

    corn noun, adjective

    tall cereal plant with large seeds (kernels) cultivated for food and industry. Also called maize.

    cosmetics Noun

    substances applied to the body to make it appear more attractive.

    cultivate Verb

    to encourage the growth of something through work and attention.

    culture Noun

    learned behavior of people, including their languages, belief systems, social structures, institutions, and material goods.

    currency Noun

    money or other resource that can be used to buy goods and services.

    developing world Noun

    nations with low per-capita income, little infrastructure, and a small middle class.

    diet Noun

    foods eaten by a specific group of people or other organisms.

    Encyclopedic Entry: diet
    digest Verb

    to convert food into nutrients that can be absorbed.

    discover Verb

    to learn or understand something for the first time.

    domestic animal Noun

    animal that has been tamed for work or to be a pet.

    edible Adjective

    able to be eaten and digested.

    einkorn Noun

    type of wheat.

    emmer Noun

    type of wheat.

    energy Noun

    capacity to do work.

    enormous Adjective

    very large.

    ethanol Noun

    type of grain alcohol used as biofuel.

    expensive Adjective

    very costly.

    familiar Adjective


    feed Noun

    processed food for livestock.

    flour Noun

    ground grain, usually of wheat.

    food Noun

    material, usually of plant or animal origin, that living organisms use to obtain nutrients.

    Encyclopedic Entry: food
    food staple Noun

    food that is eaten frequently, either fresh or stored for use all year.

    Encyclopedic Entry: food staple
    frequent Adjective


    fuel Noun

    material that provides power or energy.

    grain Noun

    harvested seed of such grasses as wheat, oats, and rice.

    Encyclopedic Entry: grain
    grain elevator Noun

    large storage facility for grains, equipped with lifting mechanisms.

    grain silo Noun

    large storage facility for grains.

    grass Noun

    type of plant with narrow leaves.

    Great Plains Noun

    grassland region of North America, between the Rocky Mountains and the Mississippi River.

    growing season Noun

    period in the year when crops and other plants grow rapidly.

    harvest Noun

    the gathering and collection of crops, including both plants and animals.

    humid Adjective

    containing a large amount of water vapor.

    inedible Adjective

    not able to be eaten or digested.

    legume Noun

    type of plant with a pod that splits, with seeds in the middle, such as peanuts.

    livestock noun, plural noun

    animals raised for sale and profit.

    machinery Noun

    mechanical appliances or tools used in manufacturing.

    maize Noun


    manufacture Verb

    to make or produce a good, usually for sale.

    millet noun, adjective

    a type of grain.

    nutrient Noun

    substance an organism needs for energy, growth, and life.

    Encyclopedic Entry: nutrient
    oatmeal Noun

    rolled or ground oats mixed with water or milk.

    oats Noun

    type of edible grass.

    protein Noun

    one of many complex compounds, made of chains of amino acids, that make up the majority of all cellular structures and are necessary for biological processes.

    raw material Noun

    matter that needs to be processed into a product to use or sell.

    remarkable Adjective

    unusual and dramatic.

    remnant Noun

    something that is left over.

    rice Noun

    grass cultivated for its seeds.

    rice paddy Noun

    rice field.

    river Noun

    large stream of flowing fresh water.

    Encyclopedic Entry: river
    rye Noun

    cereal grain grown for food.

    seed Noun

    part of a plant from which a new plant grows.

    sickle Noun

    long, curved blade attached to a handle, used for cutting many stalks of grass at once.

    sorghum Noun

    type of grain.

    stalk Noun

    stem of a plant.

    steam Verb

    to heat something by placing it over boiling water.

    sugar Noun

    type of chemical compound that is sweet-tasting and in some form essential to life.

    summer grain Noun

    grass that is harvested during the summer or autumn.

    temperate Adjective


    terrace Noun

    flat surface created on a steep hillside.

    thresh Verb

    to loosen the grain from its casing, called chaff.

    tofu Noun

    thick, soft substance of varying consistency made from soybeans.

    tortilla Noun

    flat, round bread made from corn or flour.

    tropical Adjective

    existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.

    vehicle Noun

    device used for transportation.

    vitamin Noun

    chemical substance that is necessary for health.

    wage Noun

    money or goods traded for work or service performed.

    weather Noun

    state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness.

    Encyclopedic Entry: weather
    wheat Noun

    most widely grown cereal in the world.

    winnow Verb

    to separate the grain from the inedible casing, called chaff.

    winter grain Noun

    grass that is harvested during the winter or spring.

    yield Verb

    to produce or result in.