Grain Sorghum (Milo)
P. R. Carter1, D. R. Hicks2, E. S. Oplinger1, J.
D. Doll1, L. G. Bundy1, R. T. Schuler1, and B.
1Depts. of Agronomy, soil Science, and Agricultural Engineering, Cooperative
Extension Service and college of Agricultural and Life Sciences, University of Wisconsin-Madison,
2Dept. of Agronomy and Plant Genetics, University of Minnesota, St. Paul,
Farmers on the hot, dry plains from Texas to South Dakota grow and use grain sorghum
like Corn Belt farmers use corn. Large acreages of grain sorghum are also grown
in Africa and Asia in areas where the climate is too hot and dry for corn.
During the past 25 years, the grain sorghum acreage in the U.S. has ranged from
15 to 18 million acres per year. Grain sorghum acreage is somewhat greater than
acreages for oats and barley, but considerably less than the land area planted to
corn, wheat, and soybeans.
In cooler, more humid regions, corn is usually a better choice than grain sorghum,
but renewed interest in grain sorghum occurs whenever hotter and drier than normal
growing seasons are experienced.
Worldwide, sorghum is a food grain for humans. In the United States, sorghum is
used primarily as a feed grain for livestock. Feed value of grain sorghum is similar
to corn. The grain has more protein and fat than corn, but is lower in vitamin A.
When compared with corn on a per pound basis, grain sorghum feeding value ranges
from 90% to nearly equal to corn. The grain is highly palatable to livestock, and
intake seldom limits livestock productivity. However, some sorghum varieties and
hybrids which were developed to deter birds are less palatable due to tannins and
phenolic compounds in the seed. The grain should be cracked or rolled before feeding
to cattle; this improves the portion digested.
Pasturing cattle or sheep on sorghum stubble, after the grain has been harvested,
is a common practice. Both roughage and dropped heads are utilized. Stubble with
secondary growth must be pastured carefully because of the danger of prussic acid
Grain sorghum may also be used as whole-plant silage, however another sorghum, sweet
sorghum, was developed as a silage crop. Sweet sorghum produces much higher forage
yields than grain sorghum, but feed quality will likely be lesser because there
is no grain. Some growers mix grain sorghum with soybeans to produce a higher protein
III. Growth Habits:
Grain sorghum is a grass similar to corn in vegetative appearance, but sorghum has
more tillers and more finely branched roots than corn. Growth and development of
sorghum is similar to corn, and other cereals. Sorghum seedlings are smaller than
corn due to smaller seed size. Before the 1940s, most grain sorghums were 5-7 feet
tall, which created harvesting problems. Today, sorghums have either two or three
dwarfing genes in them, and are 2-4 feet tall. While there are several grain sorghum
groups, most current grain sorghum hybrids have been developed by crossing Milo
with Kafir. Other groups include Hegari, Feterita, Durra, Shallu, and Kaoliang.
The grain sorghum head is a panicle, with spikelets in pairs. Sorghums are normally
self-fertilized, but can cross pollinate. Hybrid sorghum seed is produced utilizing
cytoplasmic male sterility. Sorghum flowers begin to open and pollinate soon after
the panicle has completely emerged from the boot. Pollen shedding begins at the
top of the panicle and progresses downward for 6-9 days. Pollination normally occurs
between 2:00 and 8:00 a.m., and fertilization takes place 6-12 hours later.
Sorghum can branch from upper stalk nodes. If drought and heat damage the main panicle,
branches can bear panicles and produce grain. The grain is free-threshing, as the
lemma and palea are removed during combining. The seed color is variable with yellow,
white, brown, and mixed classes in the grain standards. Brown-seeded types are high
in tannins, which lower palatability. Percentages of the seed components, endosperm
(82%), embryo (12%), and seed coat (5-6%) are similar to corn.
IV. Environment Requirements:
Low temperature, not length of growing season, is the limiting factor for production
in most of the Upper Midwest. Average
temperatures of at least 80Â° F during July are needed for maximum grain sorghum
yields, and daytime temperatures
of at least 90Â° F are needed for maximum photosynthesis. For example, normal average
temperatures for July are about 75Â° F in southern Wisconsin. Night temperatures
below 55Â° F for a week at the heading and pollination stage may result in heads
with very little grain. Normal night temperatures during August range from about
65Â° F in southern to 60Â° F in central Wisconsin. In September, the range is from
55Â° F in southern to 50Â° F in central Wisconsin. In southern and central Minnesota,
July and August temperatures are similar to those for southern Wisconsin. Therefore,
low temperatures may prevent successful production of grain sorghum in central and
northern Wisconsin and Minnesota or as a late-planted emergency grain crop in southern
Wisconsin and Minnesota. Plants should complete heading by early August to insure
excellent grain set.
Soil temperature at planting time is critical for grain sorghum. Sorghum seed needs
soil temperatures of 60-65Â° F for good emergence.
Three characteristics of sorghum give it a potential advantage over corn in dry
1. Corn is cross-pollinated. Severe drought at silking time may cause barren ears
(no kernels). Sorghum is self-pollinated and produces heads over a longer time period
because tillers develop over several weeks. Consequently, short periods of drought
do not seriously damage pollination and fertilization. In a longer drought, sorghum
produces fewer and smaller heads but they are rarely without kernels.
2. An optimum relationship between plant population and moisture supply is often
critical with corn but unimportant with sorghum. When soil moisture is plentiful,
sorghum heads grow large and tillers produce heads. But if drought occurs, heads
are small and fewer tillers develop. Consequently, sorghum growers can plant high
populations for potentially high yields. Corn growers can choose between high populations
for maximum yields or lower populations with less chance of serious loss from drought.
3. Sorghum foliage resists drying. At equal moisture stress, corn leaves lose a
greater percentage of their water content than do sorghum leaves. The waxy coating
on sorghum leaves and stems may be an important cause. This coating often gives
the leaf sheaths a sticky, frosty appearance.
Sorghum is more tolerant of wet soils and flooding than most of the grain crops--an
interesting phenomenon in relation to its drought tolerance. However, most of the
poorly drained, wet soils in Wisconsin and Minnesota are too cold for grain sorghum.
V. Cultural Practices:
A. Seedbed Preparation:
A seedbed similar to the one prepared for corn is also good for grain sorghum. The
use of a cultipacker or corrugated roller after seeding often gives better stands.
In warmer regions, reduced- and no-tillage systems are used for grain sorghum. Soil
temperatures may be toocold for these systems in much of the Upper Midwest.
B. Seeding Date:
Grain sorghum should be planted when soil temperatures reach 60 to 65Â° F. Generally
this is 15 to 20 days after corn planting or between May 15 and early June. Grain
yields decrease as planting is delayed after early June. Most hybrids require 90-120
days to reach maturity, therefore late-planting as an emergency crop is not recommended.
C. Method and Rate of Seeding:
1. Method of Planting: Plant grain
sorghum in rows at a depth of 1 inch in heavy soil and 1 1/2 to 2 inches in sandy
soil. Corn planters are probably the most common seeding equipment. It is important
to place the seed in moist soil to obtain fast emergence of the seedling.
A grain drill can also be used to plant the seed in narrow rows. Some adaptations
in the grain seedbox may be necessary to isolate the seed above the hole. Some growers
have attached small gas funnels above the holes in the seedbox and place the seed
in the funnels. Commercial equipment is also available for most newer drills.
2. Rate of Planting: Seed size will
influence the pounds of seed to plant per acre. As a general rule, there are approximately
16,000 sorghum seeds per pound. Most sorghum hybrids average about 75% emergence.
On soils of good fertility and adequate moisture, the recommended rate of seeding
is 8-10 pounds of seed in rows of 30-40 inches in width. At this rate of planting,
seeds will be 1 to 1 1/2 inches apart in the row with a population of 100,000 to
120,000 plants per acre.
On soils that are less fertile or more droughty, the seeding rate should be 5-6
pounds per acre.
3. Row width: The row width used
will likely depend on the equipment available. During the last few years, there
has been considerable interest in planting grain sorghum in narrow rows to boost
grain yields. With narrow rows, greater distance between plants in the row must
be planned in order to get the optimum plant population per acre. The main advantage
of narrow rows is to attain more efficient use of moisture, soil fertility, and
sunlight. Grain yields in Minnesota studies were 10-15% higher in 10-inch rows than
in 40-inch rows. The primary disadvantage is that cultivation is not possible and
weed control is dependent entirely on chemical herbicides.
D. Fertility and Lime Requirements:
Nutrient needs of sorghum closely resemble those of corn in that sorghum uses relatively
large amounts of nitrogen and moderate amounts of phosphorus and potassium. The
grain in a 100-bushel per acre grain sorghum crop removes about 100 lbs. of nitrogen,
14 lbs. of phosphorous, and 14 lbs. of potassium.
A soil test is the most practical method of determining fertilizer needs. Apply
phosphate and potash according to soil test recommendations where soil tests for
P and K are low (L) or very low (VL). Use the nitrogen and maintenance phosphate
and potash recommendations shown in Table 1. Lime soils to a pH of 6.0 to 6.5.
Table 1: Annual nitrogen, phosphate, and potash recommendations for grain sorghum.
organic matter %
Phospahate and Potash recommendation1
50 to 100
1Amounts shown are for medium (M) soil test levels. Apply 50% of this
rate if soil test is high (H) and omit if soil test is excessively high (EH).
Nitrogen can be applied in the spring as a preplant application, at planting, or
as a side dressing at cultivation. Appropriate N credits should be taken for manure
and previous legumes to reduce N fertilizer rates. A starter fertilizer may be beneficial.
E. Variety Selection:
Improved short-season grain sorghum hybrids are available, but most of the breeding
is for the major grain sorghum production areas, which have warmer, longer growing
Hybrid trials are not conducted in Wisconsin, but results of limited Minnesota trials
are reported in Miscellaneous Report 24. Hybrids listed in this publication may
be of acceptable maturity for southern Wisconsin and sandier, warmer soils in central
Wisconsin. Hybrid trials are also conducted in Iowa, but these focus on the drier,
warmer western and southern portions of that state.
F. Weed Control:
Early spring seedbed preparation followed by one or two shallow cultivations, just
before planting sorghum will kill several generations of weed seedlings and give
sorghum a chance to get ahead of the weeds. Timely cultivations of sorghum planted
in 20-inch or wider rows during the early growing stages are highly important. Sorghum
planted in narrow rows can not be cultivated, but it is a highly competitive crop
and can dominate many weeds. Several herbicides are available to compliment cultural
and mechanical practices. Quackgrass can be controlled with 1 qt/A of Roundup applied
when the weed is actively growing and has 3 to 4 leaves. Other perennial weeds such
as Canada thistle, milkweed and hemp dogbane should be suppressed the year before
sorghum is planted.
Several selective herbicides can be used in sorghum. Atrazine can be applied as
a preplant incorporated, preemergence or postemergence herbicide. Application rates
are similar to those used in corn, as are the concerns of atrazine carryover. If
crops other than corn will be planted next year, do not use atrazine in sorghum.
On the other hand, sorghum could be safely planted in fields with atrazine residues
from previous years.
Dual and Lasso can be used as a preplant or preemergence
treatment only when sorghum seed is treated with a safener. Your seed
dealer may be able to obtain safener-treated seed for you. Dual and Lasso are excellent
annual grass herbicides and could be used in combination with atrazine. If incorporated
into the upper 2 inches of soil, they suppress yellow nutsedge.
Ramrod is chemically related to Lasso and Dual but can be used preemergence in sorghum
without a chemical safener applied to the seed. It controls many annual grasses
and can be mixed with atrazine to control a broader spectrum of weeds.
Buctril, Banvel and 2,4-D are labeled for use in grain sorghum for postemergence
broadleaf weed control. Their use directions and rates are similar to those for
G. Diseases and their Control:
A seed treatment such as Captan should be used to control seed rots and seedling
blights. Leaf diseases can be problems in areas with high rainfall and humidity,
but generally do not cause serious losses. Planting resistant hybrids, providing
optimum growing conditions, rotating with other crops, removing infested debris,
planting disease-free seed are all methods which can be used to minimize losses
H. Insects and Other Predators and their Control:
Under Minnesota and Wisconsin conditions, the most serious pest problem for grain
sorghum growers is likely to be bird damage. Planting larger fields in one block
and locating these away from urban areas or farm buildings may help reduce the problem.
Grain sorghum is resistant to corn rootworms, but may be attacked by corn earworms,
aphids, and greenbugs.
Nearly all grain sorghum is harvested as a standing crop with a combine. Combining
time will depend on the fall weather and the availability of grain drying facilities.
Sorghum grain can be threshed free of the head when the seed moisture is 20-25 percent.
The seed is hysiologically mature at even higher moisture levels. Frost will generally
kill the top of the plant and help to lower the moisture content. Some hybrids have
a loose, open type head which astens field drying.
Sorghum seed is easily damaged in the threshing operation, especially when the grain
is dry. The combine platform should be operated as high as possible to minimize
the mass of stems entering the combine. If necessary, the cylinder speed can be
reduced to one-half that used for wheat to prevent cracking the seed. However, grain
moisture will normally be higher and faster cylinder speeds can be used. The recommended
cylinder speed is 750-1300 R.P.M. but loss determinations should be made to refine
the combine adjustments. An average loss of 19-22 kernels per square foot is equal
to one bushel per acre loss.
The grain sorghum crop can be harvested for high-moisture grain silage. When fed
to livestock, its digestibility will be increased by grinding or rolling. High moisture
grain sorghum can be combined and ensiled when the grain is about 25-30% moisture.
J. Drying and Storage:
Grain sorghum can be dried with corn drying equipment. However, because the grain
is smaller in size, fans may need to be operated at higher static pressure than
used for corn. Also, grain sorghum needs to be somewhat drier than corn for safe
storage since there is less air movement through the grain. Grain should be stored
at 13% moisture and in clean bins. The grain should not be heated over 200Â° F since
feeding values are reduced by high temperature.
VI. Yield Potential and Performance Results:
Grain sorghum yields exceeding 100 bushels per acre have been obtained in Wisconsin
(Table 2). Yield potential and economics of grain sorghum must be compared to corn
to determine whether or not grain sorghum offers an advantage.
On very droughty soils, or if subsoil moisture is very low, grain sorghum may out
yield corn. This occurred at the Hancock Research Station in 1971 and 1972 (Table
2). However, when conditions are more favorable for corn production, corn yields
will probably be at least 15-20% higher than for grain sorghum. This assumes that
planting dates and hybrid maturities are optimum for both crops, with the optimum
date for grain sorghum being later than for corn.
Table 2: Performance of grain sorghum compared to corn at three Wisconsin locations,
Janesville (slit loam)
Lancaster (silt loam)
--------------- Bushels/acre ---------------
When expected corn yields are less than 50-75 bushels per acre, and the reason for
the low yields is moisture stress, grain sorghum may equal or exceed corn grain
yields. However, if corn yields greater than 75 bushels per acre are anticipated,
grain sorghum is unlikely to be competitive.
VII. Economics of Production and Markets:
The cost of grain sorghum production is about the same as for similar grain-yield
production levels for corn. Therefore decisions to grow grain sorghum depend primarily
on relative yield potential compared to corn, and the ability to obtain markets.
Since market outlets for grain sorghum are not established in most areas of Minnesota
and Wisconsin, local elevators will probably not buy it. On-farm utilization as
feed is the most likely alternative available to most growers.
VIII. Information Sources:
Robinson, R.G., W.W. Nelson, J.H. Ford, and D.P. Warnes. 1977. Drought and Grain
Sorghum. Misc. Report 147, Minnesota Agr. Exp. Station.
Oplinger, E.S. 1973. Grain Sorghum Production in Wisconsin. Field Crops 24.4. Univ.
of Wis. Agronomy mimeo. 8p.
Oelke, E.A. 1971. Grain Sorghum in Minnesota. Crop News No. 12, Agronomy and Plant
Genetics, Univ. of Minn.
Varietal Trials of Farm Crops. (current year). Minnesota Report 24, Minn. Agr. Exp.
Station, p. 13.
Grain Sorghum Performance Tests. (current year). Iowa State Univ. Coop. Ext. Serv.
Pub. AG 16-7.
Vanderlip, R.L. How a Sorghum Plant Develops. 1972. Kansas State Univ. Coop. Ext.
Serv. Pub. C-447.
Taylor, R. W. (ed). 1988. Grain Sorghum : A Manual for Production and marketing.
Extension Bulletin 148, Delaware Cooperative Extension.
Grain Sorghum Production Handbook. 1987. Bulletin C-687, Cooperative Extension Service,
Kansas State University.
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