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
-richlegumes, 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.
