TECHNICAL PAPER #50
 
                         UNDERSTANDING CEREAL CROPS I
                         WHEAT, OATS, BARLEY, AND RYE
 
                                      By
                      Roy M. Stephen & Betsey Eisendrath
 
                              Technical Reviewers
                               Dr. Glen M. Wood
                               Dr. Dennis Sharma
                                   David Ray
 
                                 Published By
 
                                     VITA
                       1600 Wilson Boulevard, Suite 500
                         Arlington, Virginia 22209 USA
                     Tel: 703/276-1800 . Fax: 703/243-1865
                          Internet: pr-info@vita.org
 
                           Understanding Cereal Crops
                        I: Wheat, Oats, Barley, & Rye
                             ISBN: 0-86619-267-0
                  [C]1986, Volunteers in Technical Assistance
 
                                   PREFACE
 
This paper is one of a series published by Volunteers in Technical
Assistance to provide an introduction to specific state-of-the-art
technologies of interest to people in developing countries.
The papers are intended to be used as guidelines to help
people choose technologies that are suitable to their situations.
They are not intended to provide construction or implementation
details. People are urged to contact VITA or a similar organization
for further information and technical assistance if they
find that a particular technology seems to meet their needs.
 
The papers in the series were written, reviewed, and illustrated
almost entirely by VITA Volunteer technical experts on a purely
voluntary basis. Some 500 volunteers were involved in the production
of the first 100 titles issued, contributing approximately
5,000 hours of their time. VITA staff included Suzanne Brooks
handling typesetting and layout, and Margaret Crouch as editor
and project manager.
 
VITA Volunteer Roy Stephen is a professor of agronomy at Lake
Land College in Mattoon, Illinois. Betsy Eisendrath is a technical
writer and editor who frequently helps VITA on projects such
as this.   Dr. Glen Wood is an agronomist and professor of plant
and soil science at the University of Vermont.   VITA Volunteer
agronomist Dr. Dennis Sharma is a technical adviser to both the
private sector and government institutions through his company.
International Agricultural Consulting Services.   David Ray has
many years of farming experience, with emphasis on rice, wheat
and soybeans.  Mr. Stephen was assisted by Lisa Nichols.  Mike
Medernach, and Sharon Spray, students at Lake Land College.
 
VITA is a private, nonprofit organization that supports people
working on technical problems in developing countries. VITA offers
information and assistance aimed at helping individuals and
groups to select and implement technologies appropriate to their
situations. VITA maintains an international Inquiry Service, a
specialized documentation center, and a computerized roster of
volunteer technical consultants; manages long-term field projects;
and publishes a variety of technical manuals and papers.
 
                         UNDERSTANDING CEREAL CROPS I
                         Wheat, Oats, Barley and Rye
 
            by VITA Volunteers Roy M. Stephen and Betsy Eisendrath
 
I. INTRODUCTION
 
Cereal crops, or grains, include a wide variety of plants that
are members of the grass family (Gramineae) grown for their hard
seeds or kernels, which are used primarily for food. Grains are
rich in carbohydrates and contain substantial amounts of protein,
as well as some fat and vitamins.   They are the staple food for
most of the world's population.   Over 70 percent of the world's
harvested area is planted to grains, for an output of a billion
and a half tons a year.
 
All grains consist of the same three basic parts: (1) the
endosperm or starchy interior of the seed, the food source for
the developing seedling; (2) the germ or embryo; and (3) various
covering layers.
 
Most grains can be grown under a variety of weather and soil
conditions, and most are cultivated in a number of different
regions.  However (speaking very generally), oats and rye are
most often grown in cool climates with less fertile soils, and
wheat and barley in mild climates with better soils. Maize is
preferred in warm temperate and subtropical areas. In moist
tropical areas, rice is predominant; in drier tropical areas,
sorghum and millets.  These eight are the most widely cultivated
grains.  Less common grains, having limited production, include
wild rice and Job's tears.  There are also several plants, like
flax, buckwheat, and amaranths, that are often mistakenly referred
to as grains, but are not members of the grass family.
 
This paper focuses on production and use of wheat, oats, rye, and
barley.  "Understanding Cereal Crops II" covers maize, sorghum,
rice, and millet.
 
It is not known exactly how long ago people began to eat wild
grains, but 75,000-year-old implements have been found that may
have been used for milling them.   Grains were among the first
plants to be domesticated.  This discovery lies at the source of
recorded history, for it was the cultivation of grains that made
it possible for human beings to end their constant wanderings in
search of food.  With the cultivation of grains, they could
settle together in communities.   By 3000 B.C. they were growing
all the major grains we raise today.
 
Many of today's varieties of these grains, however, are improved
varieties that have been developed at places like the International
Rice Research Institute (IRRI) in the Philippines and the
International Maize and Wheat Improvement Center (CIMMYT, from
its name in Spanish) in Mexico.   Researchers at centers like
these work to develop strains that will produce higher yields,
lodge(*) less, tiller more, resist diseases and pests, and have an
improved nutritional value.
 
In combination with improved agricultural techniques, these hybrids
have produced dramatic increases in yields.   But there are
limitations.  To achieve the full yields of which they are capable,
they often require irrigation and increased inputs of fertilizers,
as well as of pesticides and herbicides in some cases.
These create further pressures on already strained water and fuel
resources, as well as a need for larger capital investment.
Moreover, a new variety of grain seldom remains under cultivation
for more than three to five years before new strains of diseases
and pests develop to which the variety is susceptible.
 
ADVANTAGES AND DISADVANTAGES OF GRAIN CROPS
 
Grain crops have the following advantages:
 
    1.   There is a grain crop, and often more than one, suited to
        almost any climate or soil.
 
    2.   They give farmers the highest yield per unit of land of
        any crop.
 
    3.   They can be grown using manual labor, but are well-suited
        to mechanized farming, which makes them significantly
        less labor-intensive and less expensive to produce.
 
    4.   They are easy to handle and compact to transport and
        store.
 
    5.   Under good storage conditions, they can be kept for a
        long time.
 
    6.   They are rich in starch and calories. and provide significant
        amounts of protein, as well as some fat and
        vitamins.
 
- - - - - - - - - - - - - - - -
(*)Lodge:  the tendency of the grain stem to fall over under the
weight of the seed head. Tiller: capable of producing more than
one shoot from the root of the plant.
 
The disadvantages of grain crops include the following:
 
    1. They are more vulnerable to damage from pests and diseases
       than legumes.
 
    2. They must be dried thoroughly before storing, and cannot
       be stored in a humid place.
 
    3. Their protein does not supply all essential amino acids.
       It must be supplemented with protein from other sources.
 
MAJOR USES OF GRAINS
 
Grains as Food
 
Grains supply over 65 percent of the calories that people consume
worldwide. In parts of the world where most of the grain crop is
used as human food, they supply an even higher proportion--80
percent in the Far East and Southeast Asia, and over 70 percent
in Africa and the Middle East.
 
People consume grains in a variety of forms: whole, in porridges
and soups, dried, and ground into flour that is used to make flat
and leavened breads, noodle products, and cakes and cookies.
People eat syrups and oils extracted from grains, and drink beer
and other beverages brewed from them.
 
The outer hull of most grains is indigestible and must be removed
before the grain can be eaten. Often the grain is milled further
to remove the germ and the inner layers of the endosperm's
covering.  This improves the keeping qualities of the grain and
makes it more uniform in appearance, but results in major losses
in its nutritional value.
 
Grains as Feed
 
When grain is used as animal feed, it is consumed in the form of
seeds themselves, and as pasturage, hay, and silage.   Worldwide,
animals consume about the same amount of the grain crop as people
do, but if current trends continue the animals will soon be
consuming the greater proportion.
 
Feeding grain to animals being raised for meat is an inefficient
use of the crop.  It takes, for example, 4 kilograms of grain to
produce 1 kilogram of pork, and between 7 and 8 kilograms of
grain to produce 1 kilogram of beef.
 
Nonfood Uses of Grains
 
The nonfood uses of grains are much less important than the food
uses.  Hulls are used as fuel and mulch, and straw is used as a
packing, thatching, and bedding material.   Grains are used
industrially in the manufacture of soaps, solvents, alcohols,
plastics, and paper.
 
II. MAJOR GRAIN CROPS
 
This section summarizes the cultivation requirements and primary
uses of four major grains--wheat, oats, barley, and rye. More
detailed information for specific grains on specific sites may be
obtained from local agricultural extension services, ministries,
and research stations.
 
WHEAT
 
More hectares of land worldwide are devoted to wheat than any
other crop.  Wheat has been cultivated since before recorded
history.  It probably originated in western Asia; it was being
grown along the Nile by 5000 B.C., in China by 3000 B.C., and was
imported in Greek and Roman times.   Today the chief producing
countries are the Soviet Union, United States, China, India,
France, and Canada.
 
There are thousands of varieties of wheat. Three important types
are common or bread wheat (Triticum vulgare or T. aestivum),
club wheat (Triticum compactum), and durum wheat (Triticum durum).
 
Wheat may be classified as hard or soft.   Hard wheats, generally
grown in the more arid wheat-producing regions, have higher
protein content than soft wheats.   Most of this protein is in
the form of gluten.  Hard wheat produces what are called strong
flours.  Strong flours have granular texture, with small, hard
grains of starch and a high proportion of gluten.   They can
absorb large quantities of water, and are particularly suited to
bread-making.  Durum is a kind of hard wheat used mainly to make
noodle products.  Soft wheats (further subdivided into red and
white wheats) usually grow where rainfall is plentiful.   Flour
made from soft wheat has larger, softer grains than flour from
hard wheat.  It contains a lower proportion of gluten and can
absorb relatively little water.   This limits its suitability for
bread-making.  Is is often called pastry flour, and is used
mainly for making cakes and cookies.   Most of the wheat produced
in Australia and Western Europe is soft wheat; elsewhere, hard
wheat is predominant.
 
The main wheat-producing regions of the world lie in the
temperate zones.  Wheat is adaptable to a wide range of growing
conditions, but is best suited to cool climates with moderate
rainfall.  Cool weather is especially important during the
tillering and early growth stages.   In tropical countries, wheat
is usually grown at high altitudes, but it can be grown in lower,
warmer areas if the humidity is low.
 
Wheat needs 25 to 100 centimeters of rainfall a year in the
cooler climates where it is most common; in hot areas, it requires
50 to 175 centimeters.  It can be grown under irrigation
where the rainfall is insufficient.   Prolonged drought without
irrigation reduces yields. Relatively dry areas produce wheat of
higher quality than humid or irrigated areas do, but yields in
dry areas are substantially smaller. Rusts and other diseases
that attack wheat flourish in hot, humid areas.
 
Wheat can be grown on a wide range of soils, but does best on
well-drained, fertile soils of medium to heavy texture. Silt and
clay loams usually give the best yields, but wheat also does very
well on fine sandy loams and clay soils. Very heavy or very sandy
soils should be avoided.
 
Production
 
Bread wheats can be divided into two groups, winter wheats and
spring wheats, depending on how they are cultivated.   Winter
wheats are planted in the fall for harvest the following summer.
They cannot be cultivated where winters are too severe, but where
they can survive winter, they produce a larger yield than spring
wheats.  Winter wheats are grown in most of the world's major
wheat-producing ares.  Spring wheats are grown where the winters
are too severe for winter wheats; they also do better than winter
wheats in warm climates. Spring wheats are usually sown in March
in the northern hemisphere, for harvest in the autumn.   They have
a shorter growing season than do winter wheats, but require at
least 90 days, so they should be planted as early as the soil can
be worked.
 
Wheat may be grown alone or mixed or in rotation, often with a
leguminous crop.  Methods of cultivation vary according to the
type of wheat and to climate and soil conditions.   The ground is
thoroughly cultivated, either by hand or by machine. The seedbed
should be well-pulverized but compact.   If beds for irrigation
are to be used, they are made just before sowing, fertilizer is
often broadcast, and a presowing irrigation is performed.
 
The rate of seeding varies between 22 and 135 kilograms per hectare
(the larger amounts are used where moisture is plentiful.
Seed may be broadcast by hand, but this can result in fairly poor
germination, wasted seed, and an irregular plant stand.   Drill
seeding in rows can alleviate these problems and produce higher
yields.  The seed is usually deposited in a moist seedbed and
covered with 2.5-7.5 centimeters of packed soil, deeper only when
the climate is very dry.
 
Wheat takes up most nutrients from the soil before it blooms, but
continues to take up nitrogen until the grain is ripe. It usually
responds to fertilizers. Applications of nitrogen range from
34 to 135 kilograms per hectare. Heavier amounts are applied in
regions where there is more moisture in the soil.   Too much
fertilizer can reduce yields by causing plants to lodge and by
delaying maturity so the crop becomes more subject to damage from
rusts. Semidwarf wheats can take up larger amounts of nitrogen
without lodging, enabling them to produce larger yields. Phosphorus
is usually applied at 34 to 56 kilograms per hectare, especially
in humid regions; potassium, at 23 to 56 kilograms per
hectare.  Manure and compost may be used, and green manuring is
sometimes practiced.
 
Spring wheats can mature in as little as three months, more
quickly than winter wheats, which usually grow five to six months
in the tropics, and often longer elsewhere.   Wheat is usually
harvested with a sickle, or mechanically with a combine, when the
grain is completely ripe and the straw is brittle and golden.
The moisture content of the grain must be 13 percent or less. If
it is higher, the grain needs to be dried before it can be safely
stored.
 
The average yield for wheat worldwide is about 1,600 kilograms
per hectare, but the range is enormous, and far higher yields
have been obtained with hybrid cultivars on intensively managed
lands.
 
As long as it is kept clean, cool, dry (no more than 12-13 percent
moisture), and free from insects, wheat can be stored almost
indefinitely.  For this reason, wheat is often stockpiled for
distribution during famines.
 
 
Diseases and Pests
 
Wheat is subject to many diseases and insect pests. Wheats resistant
to some diseases and pests have been developed, but no wheat
variety is resistant to all.
 
Black stem rust (Puccinia graminis) is one of the worst and most
common diseases. Its spores are carried on barberry plants and on
the wind. Much of the infection can be avoided by early sowing.
Wheat is also susceptible to several smuts; crop rotation and
clean seed are used against them. The poisonous fungus ergot
sometimes attacks wheat, but is less common in wheat than in rye.
 
The most common insect pests include grasshoppers, which are
sometimes sprayed from airplanes, and Hessian fly (Mayetiola
destructor), which can be limited by timing the planting of the
wheat to avoid the main brood of insects.   The wheat stem sawfly
(Cephus cinctus) is another insect enemy of wheat.
 
Uses
 
Wheat seeds are ground into flour for human consumption.  Wheat
is an important ingredient in many breads, biscuits, cookies,
cakes, dumplings, noodles, breakfast foods, and beer. Immature
wheat makes good forage for livestock, and by-products of milling
are widely used as animal feed.   There are also nonfood uses.
Wheat straw is used as a mulch, and as a weaving and stuffing
material.  In industry, wheat is an ingredient in emulsifiers,
adhesives, and polishes.
 
Wheats vary in their protein content, but hard wheats average 13-
16 percent, and soft wheats 8-10 percent. The protein is deficient
in lysine, one of the essential amino acids. The wheat germ
and bran are high in niacin, thiamine, riboflavin, and vitamin K,
as well as phosphorus and iron. However, the more refined the
flour is, the more of these nutrients are lost. A highly refined
flour may contain about one ninth of the niacin. a fifth of the
thiamine, and a quarter of the riboflavin that the original,
wholegrain flour contained.  Some flours are enriched to restore
some of the lost nutrients.
 
Triticale
 
Considerable research effort has gone into developing tritacale,
a hybrid of wheat and rye. It is somewhat higher in protein
content than wheat, and can be grown in places where wheat does
not do well. However, its yields have been undependable, and its
protein is low in gluten. These and other drawbacks have not been
totally overcome and triticale is still not very widely grown.
 
OATS
 
About 50 million tons of oats are grown worldwide each year.
Avena sativa is the most common species. (Oats are relative
latecomers to the domesticated cereals, since they were probably
not raised until around 2500 B.C., with cultivation be-ginning in
North Africa, the Near East, and the temperate parts of Russia.
Oats are widely grown in temperate zones, especially in North
America, the Soviet-Union, and northern Europe. Outside these
areas, there is considerable production in China, Argentina,
Australia, and Algeria. Oats are fairly new to tropical areas,
and not very important there. In such areas, they are grown
mainly at high altitudes during the cool season.
 
While oats are generally tolerant of a wider range of climate,
soils, and agricultural techniques than are most other cereals,
winter types of oats are actually less hardy than rye, wheat, or
barley. Oats are best suited to cool, moist climates, but can
also be grown under irrigation. Hot dry weather causes developing
oat grains to wither or fill poorly. Heat damage can be limited
to some extent by selecting early varieties, particularly of red
oats (Avena byzantina), or better yet some of the heat-resistant
hybrids that have been developed. Oats can do well on a variety
of soils. They grow best on rich, friable loams, especially silt
and clay loams, that are well drained. Oats are often grown in
rotation. In cooler regions, maize is the crop that most often
precedes oats.
 
Production
 
Oat culture is fairly simple.   First the land is usually plowed
and harrowed, sometimes more than once.   Then the seed is sown
broadcast or drilled in rows.   Most often, it is sown broadcast
when the crop is for fodder, and drilled in rows 23 to 30 centimeters
apart when it is for grain.  The seed rate averages 90
kilograms per hectare, less when the oats are broadcast in dry
regions or are a companion crop for legumes.
 
Like wheat, oats can be divided into winter and spring types,
depending on when they are planted.   In the northern hemisphere,
oats are usually sown sometime between October and December, but
almost any month of the year oats are being sown somewhere in the
world.  When they are a spring crop, they are planted as soon as
the weather is warm enough for the land to be worked.   Planting
must be done before the average temperature reaches 10[degrees]C.
 
The fertilizer requirements for oats are similar to those for
wheat.  Nitrogen is the most important element, but applications
of more than 34 to 67 kilograms per hectare are likely to cause
lodging.  Often, for a grain crop, this is avoided by applying
the manure or chemical fertilizer to the crop preceding the oats
in the rotation.  Nitrogen may be applied directly to the fodder
crop at the rate of 38 to 45 kilograms per hectare.   Stiffstrawed
cultivars that can accept heavy fertilization without
lodging have been developed.   Oats also respond well to phosphorus,
and often to potassium, in humid areas.
 
Oats are not usually intercultivated.   If they are being grown
under irrigation, they receive three or four irrigations. If they
are being grown for fodder, they are usually cut between one and
three times, and then the plants are allowed to set seed.
 
Oats planted in the spring are usually ready for harvest in about
three months.  Winter crops take longer to mature: if the oats
are sown in October, the grain will ripen in April.   Premature
harvesting lowers yields of both grain and straw, but harvesting
too late increases losses of grain through shattering.   Oats
usually yield 10.75 to 21.5 quintals per acre of grain.
 
Diseases and Pests
 
The main diseases that attack oats are smut and rust. Smut is
prevented by seed treatment. There is no remedy for rust, but
hybrids resistant to the disease have been developed. Another
disease that damages oats is Septoria, which is most likely to
develop during rainy or humid weather; chemicals are used to
combat it. The greatest insect threats come from the spring grain
aphids, the chinch bug, and the armyworm.
 
Uses
 
Oats are used mainly as animal feed. The young leaves are very
nutritious and high in protein. They can be pastured or cut for
hay before maturity. The grain can be fed by itself or as part of
mixtures. The straw is used as an emergency feed and as animal
bedding. Oats are often fed whole to horses and sheep; for cattle
they are usually ground or chopped.
 
Human beings consume oats mostly in the form of oatmeal made from
rolled oats. Their protein does not make oats suitable for breadmaking,
but they can be used in cookies and cakes. The oat grain
is quite high in fat and protein. Its usual protein content is
12-13 percent, but Avena sterilis with a protein content as high
as 30 percent has been bred experimentally. Oats are a very good
source of vitamin B1. They contain an appreciable amount of
vitamin E and the same amount of riboflavin as other grains, but
much less niacin than wheat.
 
Oats are put to a number of uses in industry, one of the most
important of which is for the manufacture of furfural, a widely
used solvent made from oat hulls.
 
Nitrate Poisoning
 
Certain soil and climate conditions may cause growing oat plants
to contain high enough levels of nitrates to be poisonous to
livestock. Ample applications of phosphate may help prevent this.
The symptoms of nitrate poisoning include rapid breathing and a
blueing of the mucous membranes; death occurs from asphyxiation.
The remedy is an early intravenous injection of methylene blue,
at a dose of 4 milligrams of methylene blue per pound of body
weight in a 4 percent solution with distilled water.
 
BARLEY
 
There are a number of species of barley, the most common of which
is Hordeum vulgare. (Barley was one of the earliest cereals to be
domesticated, probably originally in the Near East. It was in use
as a food for people and animals in China around 2800 B.C. and in
Stone Age Europe). Barley was the most important grain for breadmaking
in Europe until around the 16th century, when it was
gradually replaced by wheat and rye. Today, the Soviet Union is
by far the biggest producer, followed by France, Canada, and the
United Kingdom. Important producers outside Europe and North
America include Turkey, India, Morocco, and Korea.
 
Barley does best in temperate regions where the climate is cool,
but it can adapt better than any other cereal to extremes of climate,
as well as to salinity, drought, and summer frost. It is
cultivated farther north than any other cereal, to the edges of
the Arctic, and at altitudes of 4,572 meters in the Himalayas.
Winter types, however, are less cold hardy than rye and wheat. It
does best when the growing season is 90 days or more but can
reach maturity in as little as two to three months. It is superior
to other grains in its ability to withstand dry heat; it
does very well on the desert margins where rainfall is very
limited, as in North Africa, where it is the most important
grain.
 
Barley is most often grown on light soils, but it does best on
well-drained, even-textured loams of fair fertility. Barley needs
a more porous soil than wheat does, and can tolerate alkalinity
better. It is unsuited to acid soils with a pH below 6; these
cause aluminum toxicity, which retards root growth. (This toxicity
can be corrected with calcium applications.)
 
Barley can be grown unirrigated in areas where there is between
38 and 51 centimeters of rainfall.   Where the climate is drier,
irrigation is needed.
 
Yields for barley range between 1,120 and 2,240 kilograms per
hectare depending upon variety, soil, and climate.
 
Production
 
Like wheat and oats, barley can be divided into spring and winter
types. Spring barleys can be planted farther north than any other
grain. In warmer climates, barley is usually sown in fall or
winter. In the northern hemisphere, the best time for planting is
usually between the middle of October and the middle of November.
 
Barley is most commonly planted in rotations; it is also often a
companion crop with grasses and small-seeded clovers.   The
seedbed should be well prepared, though cultivation for barley is
usually less thorough than for wheat.   Nevertheless, the best
yields of barley come from soil that is well tilled and
completely free of weeds.  Three or four plowings with a wooden
plow or one plowing with an improved iron plow, followed by a
harrowing, should be adequate.   Unlike wheat, barley needs a
seedbed that is slightly loose.
 
The seed may be broadcast, or drilled in rows 15 to 23 centimeters
apart.  It should be sown about 4 centimeters deep in
humid areas, and deeper where the soil is drier.   The usual
seeding rate ranges from 54 to 135 kilograms per hectare, with
the smaller quantities in drier regions.
 
Intercultivation is not normally practiced with barley unless the
soil is very weedy.  If this is the case, then it is useful to
hand-weed and hoe once.  An irrigated crop needs two or three
irrigations; generally speaking, barley needs less water than
wheat does.
 
Barley usually responds well to an application of 28 to 56 kilograms
of nitrogen per hectare, the larger quantities going on
moist soils.  An excess of nitrogen can cause lodging and lower
the malting quality of the grain. On some soils, the barley crop
is not fertilized directly, but draws on nutrients in the manure,
compost, or commercial fertilizer that was applied to the preceding
crop in the rotation.
 
Barley is usually harvested when fully ripe, that is, when a dent
made in the kernel with a thumbnail stays visible for some time.
The crop can be harvested by hand or by machine.   Harvesting in
the early morning can sometimes help reduce losses from
shattering.  Barley is often dried in windrows to reduce the
moisture of the grain, which should be 14 percent, or preferably
12 percent, for safe storage.   It should be stored under
moistureproof conditions.
 
Diseases and Pests
 
Barley is subject to many of the same diseases and pests that
attack wheat. These include rusts, stripe, scab, and rot. It is
susceptible to the parasitic fungi of the Helminthosporium species
and to several smuts. Barley seeds can be chemically treated
against scab, smut, or stripe, but the most effective approach is
to grow disease-resistant varieties.
 
A number of approaches are used to limit infestation of barley by
insects.  Wireworm infestation can be reduced by using a crop
rotation that includes species not subject to attack (such as
clover, soybeans, flax, or buckwheat). Time of planting can play
a role in controlling Hessian flies, which live no more than 10
days, and aphids.  Chinch bugs can be trapped as they migrate,
and induced with lures to lay their eggs where they can be
destroyed. Chemical treatment can also be used.
 
Uses
 
The main uses of barley are to make malt and to feed animals. The
most important use of barley for human consumption is for malt,
used primarily in brewing beer, but also in the manufacture of
breakfast food and confections.   Malt is prepared by soaking and
germinating barley.  Since only unbroken grains will germinate,
care in the threshing and handling of barley is particularly
important. High protein content is not desirable in a barley
grown for malt. Otherwise, barley in human food is eaten primarily
in the form of pearl barley, which is barley that has been
dehulled and mechanically polished in the same way that oats
sometimes are. Barley is a staple food grain in parts of Asia and
North Africa, where it is eaten as a porridge or flatbread.
Because of its low gluten content, barley flour cannot produce a
porous bread.
 
Because of its hull, barley contains 5 percent less digestible
material than maize does, and its feeding value for animals is
considered to be 95 percent that of maize; compared to maize,
barley contains about the same percentage of carbohydrates, a
little more protein, and a little less fat. Barley is considered
particularly well suited to fattening cattle and hogs.   It is
usually ground or rolled before being fed to any animal except
sheep.  Its straw is of a soft type that can be used as a bulk
roughage feed or as animal bedding.
 
RYE
 
Rye (Secale cereale) was probably first grown in the eastern
Mediterranean area or in western Asia.   It was the last of the
cereal crops to come under cultivation, and even now is the least
important economically.  The principal rye-growing areas are the
Soviet Union, eastern and central Europe, the United States,
Turkey, and Canada. Production is declining because of consumer
preference for wheat, and because of wheat's higher yields.
 
Rye is grown primarily for grain, but sometimes for pasturage and
hay, and as a cover crop.  It is an annual, but it sometimes
tends to maintain itself as a perennial by sprouting from its
stubble. It is grown primarily in temperate and cool nonhumid
regions. The ability of spring rye to withstand cold is greater
than that of any other grain except barley, which may equal it.
It can be grown as far north as the Arctic Circle, and at altitudes
of up to 4,270 meters.  It is also grown in warmer areas,
but production there is much less than where it is colder.
 
Rye grows quite dependably on poor soils, and can produce yields
on soils considered too poor for wheat. It responds well to
fertile land and good care, but usually the better soils are
reserved for other crops, and the poorer, sandier soils are used
to plant rye. Rye benefits from fertilizers, especially nitrogen;
up to 134 kilograms per hectare can be applied. Too much nitrogen
will promote lodging in rye grown for grain, but a spring top-
dressing of nitrogen may be used where the rye is being grown for
pasturage.
 
Production
 
Rye is grown in much the same way as other small grains.  Like
wheat, it can be grown as a winter crop or a spring crop; winter
rye is most common.  Winter rye is sown at about the same time
that winter wheat is sown, but the timing is not as important
with rye, because it is more resistant to cold than wheat is.
Winter rye can be sown almost any time during the late summer or
early fall for harvest the following summer; early seeding
produces the most fall pasture.   Spring rye should be planted as
early as possible. Rye can be grown continuously or in rotation.
Rye for pasture or green manure is often grown in mixtures with
winter legumes.
 
The land may be disked or plowed.   Rye is sown broadcast or
drilled. Sometimes it is drilled directly into small-grain stubble,
without preparing the soil; this is satisfactory if the land
is fairly free from weeds.  Rye is seeded at between 63 and 125
kilograms per hectare.  The lower rates are commonly used when
the rye is being grown for grain, the higher rates when it is to
be pastured or used to suppress weeds.
 
Rye ripens the earliest of the small grains; it is usually ready
about a week before winter wheat. It has the tallest and strongest
straw of the small grains, which makes harvesting difficult.
The average yield worldwide is 1,560 kilograms per hectare.
 
 
Diseases and Pests
 
Rye suffers less from most diseases than any of the other grain
crops.  Its only serious enemy is the parasitic fungus ergot
(Claviceps purpurea).  The fungus penetrates the developing
kernel and produces a large purplish mass that contains several
highly poisonous substances.
 
Uses
 
Rye is the richest in carbohydrates of all the cereal crops, and
contains less fat than wheat. Its vitamin B1 content is a little
lower than that of barley and wheat, and much lower than that of
oats. Rye flour can be used for bread-making, but pro-duces a
compact, heavy loaf compared to a loaf made from wheat flour. For
this reason, rye flour is usually mixed with wheat flour for
bread-making. Rye is also used to make alcoholic beverages.
 
The most important use of rye is for animal feed. Its leaves are
high in vitamin A. It is grazed and fed as hay. Since rye grains
are sticky to chew and not very palatable, they are usually
ground and fed to animals in mixture with other grains. Rye
seldom makes up more than a third of the mixture.
 
Rye is often used as a cover crop to prevent soil erosion, and as
a smother crop to limit weeds.   It is sometimes plowed under be
fore flowering, for use as green manure.   Its straw, which is
tough for animal feed, is used as a packing material, and to make
thatching and matting.
 
III. QUESTIONS TO ASK BEFORE PLANTING A GRAIN CROP
 
The overview presented above is intended to give the reader a
sense of the requirements of the various grain crops. Before attempting
to raise any grain in an area where it is not presently
grown there are a number of preliminary questions that should be
answered.  Further guidance should be obtained from local agricultural
specialists.
 
Some of the questions to be considered are:
 
    1.   Is the climate suitable for this crop?
 
    2.   Are the type of soil and its pH and salinity characteristics
        known, and are they suitable for this crop?
 
    3.   Are fertilizers available to meet the crop's nitrogen,
        phosphate, and potassium needs?
 
    4.   Can the crop's moisture needs be met through naturally
        available water?  If not, is enough water available for
        irrigation?  Does the cost of irrigation compare favorably
        with the benefits the crop will yield?  Is the
        necessary equipment available? Is the terrain suitable?
 
    5.   Have sources of supply been found for seeds, fertilizers,
        pesticides, herbicides, equipment, and anything else that
        may be needed for growing this crop?
 
    6.   Is enough capital available to purchase the necessary
        equipment and supplies?
 
    7.   Is the farmer able to invest the time and effort needed
        to grow the crop successfully?
 
    8.   Has the information been gathered about the varieties and
        hybrids that are available? Has a choice been made about
        the variety to be planted?
 
    9.   What kind of erosion control, if any, will be necessary
        if this crop is planted?  Are the resources for carrying
        it out available?
 
   10.   If part of the harvest is to be kept for later use, are
        storage facilities available that can keep the grain
        cool, dry, and safe from pests?
 
   11.   Is there a market for the grain products?
 
                                 BIBLIOGRAPHY
 
"Barley," "Corn," "Food," "Grain," "Oats," and "Rye."   The Encyclopedia
    Americana. (1984).
 
"Cereals and Other Starch Products."   The New Encyclopedia
    Britannica. (Macropaedia) (1984).
 
"Food" and "Wheat."   Colliers Encyclopedia. (1984).
 
"Grain Production."   Everyman's Encyclopaedia. (1978).
 
Hanson, Borlaug, and Anderson.   Wheat in the Third World.
    Boulder, Colorado: Westview Press, 1982.
 
Hubbell, Donald S.  Tropical Agriculture: An Abridged Field
    Guide.   Kansas City, Missouri: Howard W. Sams International
    Corp., 1965.
 
Kahn, E.J., Jr.  "The Staffs of Life: The Golden Thread." The
    New Yorker, June 18, 1984, pp. 46-88. (about corn)
 
Kahn. E.J., Jr.  "The Staffs Of Life:  Fiat Panis." The New
    Yorker, December 17, 1984, pp. 57-106. (about wheat)
 
Kassam, A.H.  Crops of the West African Semi-arid Tropics.
    Hyderabad, India:  International Crops Research Institute
    for the Institute for the Semi-arid Tropics, 1976.
 
Martin, Leonard, and Stamp.  Principles of Field Crop Production.
    New York: Macmillan Press, 1986.
 
Poehlman, John M.  Breeding Field Crops. Westport, Connecticut:
    Avi Publishers, 1979.
 
Schery, Robert W.  Plants for Man.  2nd edition. Englewood
    Cliffs, New Jersey: Prentice-Hall, Inc., 1972.
 
Uichanco, Leopoldo B., editor.   Philippine Agriculture. College
    of Agriculture, University of the Philippines, 1959.
 
Vickery, Margaret L. and Vickery, Brian.   Plant Products of
    Tropical Africa  London:   The Macmillan Press Ltd., 1979.
 
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