MF-2388 • Crop Production
DEPARTMENT OF AGRONOMY
Row spacings have 100 bushels per acre, row
been of interest in crop spacings had less effect
production for decades. on yields (Table 1). When
Yield increases from nar-
row rows have been attrib-
uted to better light
Narrow-row averaged across these
locations, yields from all
three row spacings were
interception and more
efficient water use. Plant
Grain Sorghum within 3 bushels per acre.
Studies conducted at
productivity is at its high-
est near the time the crop
closes the canopy, there-
Production in Hays in the 1970s reported
9-bushel per acre yield
advantage to 12-inch rows
fore, a crop that closes its
canopy earlier in the
growing season should
Kansas compared to conventional
36-inch rows. The advan-
tage of narrow rows was
have an advantage over a most consistent when
crop with slower canopy planting in mid to late
development. June with seeding rates
Increasing grain sor- two to three times higher
ghum yields by using nar- than the recommended
row rows has been studied seeding rates. A study
at Kansas State University conducted at Garden City
at various time during the past 20 years. The following from 1977 to 1980 found a less consistent advantage to
section will discuss managing narrow-row grain sor- narrow (10-inch) rows compared to wide (30-inch) rows.
ghum production in Kansas. However, results from individual years did indicate that
when subsoil moisture is good prior to planting, yields
Agronomic Considerations from sorghum planted in 10-inch rows at 50,000 to
for Narrow-row Grain Sorghum 75,000 plants per acre were equal to, or exceeded yields
Growing Conditions from the low-population-
Research conducted in Considerations for narrow-row sorghum wide rows.
eastern Kansas indicated that • Greatest yield advantage under high-yield environ- These studies conducted
row-spacing responses ments (good soil moisture at planting time in western
across Kansas found that
depend on the growing Kansas and highly productive soils).
condition’s effects on yield • Later planting dates typically show yield advantage.
moisture (both subsoil
potentials (Table 1). For the • Select hybrids based on yield, standability, stalk rot and
moisture and rainfall) was
three locations with average charcoal rot resistance, and stay-green characteristics.
adequate, narrow rows were
yields above 100 bushels per • Weed control can be enhanced because of quick more productive than wide
acre, sorghum in 10-inch canopy closure.
rows. When moisture was
rows yielded 12 bushels per • Maintain seeding rates similar to those used in wide
limited, grain yields were
acre more than in 20-inch rows (perhaps increase 10 percent if using a grain drill).
equal across all row spac-
rows and 15 bushels per acre • Grain drills, air seeders, or planters adjusted to narrow- ings. The exception was full
more than the 30-inch rows. row spacings can be used successfully.
season hybrids planted at
Yields in the 20-inch rows • Conventional, reduced, or no-till seedbed preparation
Garden City in a continuous
were only 4 bushels per acre can be used similar to wide rows.
sorghum system with little
more than in the 30-inch • Cultivation as an alternative for weed control is
stored soil moisture at
rows suggesting that the extremely difficult in rows less than 20 inches wide.
planting. Under these
biggest increase comes from • Use of row-crop head will not be possible for harvest conditions, the low popula-
very narrow rows. in narrow rows.
tion-wide row spacings
When moisture stress • Spraying with narrow profile tire sprayers is advisable
produced higher yields.
reduced the yields below to minimize traffic injury to sorghum plants.
Kansas State University Agricultural Experiment Station and Cooperative Extension Service
Sorghum’s drought tolerance reduces the risk of with the seed, this can also be accomplished with a grain
narrow-row grain sorghum production in Kansas. In drill fitted with fertilizer tanks or boxes. Narrow rows
high rainfall years or on highly productive soils, narrow also have the advantage when placing fertilizer with the
rows produce higher yields than conventional row seed in that the recommended rate of nitrogen containing
spacings. However, in most low-yielding environments, fertilizer can increase from 10 pounds nitrogen per acre
narrow rows will produce grain yields similar to wide to 15 or 20 pounds nitrogen per acre (depending on
rows. This enables producers to adopt narrow rows in narrow-row spacing) since the fertilizer concentration in
most sorghum producing situations. a given row is reduced as more rows are planted. If a
producer is currently applying phosphorous fertilizer in a
Tillage systems band next to the planted row (2 × 2 placement), then
Adapting narrow rows to either conventional, minimum fertilizer placement shanks can be used to achieve the
or no-tillage systems is certainly possible if key issues are same type of placement on a grain drill.
considered. The management difference between the
tillage systems deal primarily with pest control and Planting Date Considerations
nutrient placement. In most scenarios, pest management The ability of narrow rows to quickly develop a canopy
strategies that work under a given tillage system will work makes it more advantageous for later planting dates. When
in narrow rows in that tillage system. Herbicide and planting is delayed as a result of weather conditions or
insecticide application equipment for narrow rows will be grain sorghum is being double cropped after wheat,
discussed in the Machinery Considerations section. One narrow rows should be considered to increase grain yields.
consideration from a disease standpoint for narrow-row In western Kansas, delayed planting also allows more soil
sorghum production using no-till would be selecting a moisture to be stored for the sorghum crop and time to
hybrid with good resistance to sooty stripe. Sooty stripe is control additional flushes of weeds.
a fungal disease in which the growing crop is infected
from spores that overwinter on sorghum residue from the Seeding Rates and Hybrid Selection
previous year’s crop. The disease spreads rapidly when the Grain sorghum adapts to the conditions it is grown
relative humidity in the crop canopy is high. The quicker under by producing more heads per plant (tillers), seeds
developing canopy of narrow-row sorghum may increase per head and even by increasing seed weight. Research
the spread of the disease in a high-residue system. studies indicate that sorghum yields in eastern Kansas
Placement of fertilizer in a no-till system should also are maximized as long as plant populations of more
be considered when adopting narrow-row grain sorghum than 40,000 plants per acre are achieved. This yield
production. For the most part, the nitrogen application response to plant populations was consistent regardless
methods used in each tillage system under wide rows of row spacings in studies conducted in 1995 and 1996
will work adequately in narrow rows. However, the in northeast Kansas (Table 2).
placement of phosphorous fertilizer may be a greater In western Kansas, subsoil moisture and hybrid
challenge in narrow rows. If a producer is currently maturity needs to be considered when selecting a
applying phosphorous fertilizer with the planter in a band seeding rate. When subsoil moisture is adequate (after a
Table 1. Grain sorghum grain yields for three row spacings in seven environments in Kansas.
Location - Years1
Row Manhattan2 Powhattan2 Belleville2 Manhattan2 Belleville2 Manhattan3 Wellington4
Spacing 1995 1995 1995 1996 1996 1997 1997
(in) Grain Yield (bu/a)
10 137.5 92.1 77.1 122.7 117.9 83.6 77.2
20 115.0 93.4 77.8 119.6 108.8 —— —
30 115.1 83.8 90.4 113.3 102.5 84.3 79.9
LSD*(0.05) - - - - - - - - - - - - - - - 12.2 - - - - - - - - - - - - - - - NS† NS†
Planting dates ranged from May 22 to June 6 across all seven environments. 2Averaged across three plant populations and
two hybrids. 3Averaged across three plant populations. 4Averaged across two hybrids.* LSD Least Significant Difference, used
to determine if two means are statistically different. †NS—Not significantly different based on the statistical methods used.
Table 2. Two-year average grain sorghum yields for Machinery Considerations
three plant populations at Belleville and Manhattan. for Narrow-row Grain Sorghum
Growing narrow-row grain sorghum likely will not
Plant Population Belleville Manhattan
require equipment changes for most growers. There are,
(plants/acre) Grain Yield (bu/acre)
however, some items most growers should consider
30,000 101 117 when planting sorghum in narrow rows. For this discus-
60,000 106 122 sion, equipment considerations will be divided into
90,000 107 120 planting, crop management, and harvesting.
LSD(0.05) NS NS
fallow period or above average winter rainfall), re- Growers have three basic options for planting narrow-
search indicates that seeding rates for narrow rows row grain sorghum, drills, air seeders, and split-row
should be set to achieve final stands of 50,000 to planters. Since most growers have a grain drill, this is an
75,000 plants per acre if early to medium-maturing easy option. However, setting the seed metering rate low
hybrids are used. If narrow-row sorghum is to be enough may be a problem. Be sure to check the calibra-
planted in a continuous sorghum cropping system or if tion charts in the operators manual to determine the
a full season hybrid is being used, typical seeding rates proper settings. Remember, this is a starting point and
of 20,000 to 50,000 seeds per acre should be used. the calibration should be checked after a known acreage
When selecting a hybrid for grain sorghum production is seeded. Make sure seeding depth is set correctly and
in narrow rows, grain yield should still be the primary good seed to soil contact is obtained when using a drill.
focus. After selecting hybrids for yield potential, a second- Keep in mind, establishment rates with a drill are often
ary concern should be standability. Standability can be lower than with a planter, so seeding rates should be
important since harvesting lodged plants in a narrow-row increased 10 to 20 percent to achieve similar plant
production system will be more difficult compared to populations as achieved when using a planter.
conventional row spacings. Growers should scrutinize a Air seeders, another option for seeding narrow-row
given hybrids ratings for standability, stalk rot and char- crops, were popular in Kansas a few years ago, but that
coal rot resistance, and stay-green ratings. These ratings popularity had declined. However, new styles of air
can give a producer indications of a hybrids ability to seeders have led to resurgence in popularity. New
stand under adverse growing and harvesting conditions. designs of air seeders include better metering and
different options for openers, including some disc
Weed Competition and Weed Control models. The better openers allow for better seed
Light interception advantages of narrow-row sor- placement. Air seeders are typically wide, resulting in
ghum systems offer weed control advantages over greater seed capacities than most grain drills. They also
wider rows since early canopy closure reduces the are versatile enough to plant many different crops in a
number of weeds that emerge during the growing wide range of conditions. The main disadvantage of air
season. Research conducted at Kansas State University seeders is their initial cost.
indicated that the growth of weeds that did emerge was Using a split-row planter, a planter that has row units
reduced in the 10-inch rows by 24 percent compared to positioned to split the middles of the conventional row
the 20-inch rows and by 45 percent when compared to spacing allowing for planting in narrow rows, will
the 30-inch rows. Under heavy broadleaf weed pres- result in more uniform stands than a grain drill as
sure, the 10-inch rows produced 6 bushels per acre planters give better seed to soil contact than most drills
more grain than the 20-inch rows and 31 bushels per and tend to provide more uniform stands. Split-row
acre more grain than the 30-inch rows. planters will achieve better seed metering than a grain
Since cultivation is not possible, herbicides are drill at the lower seeding rates seeding typically used
required for in-season weed control in narrow rows. For for grain sorghum. The main disadvantage of split-row
control of grassy weeds, soil-applied herbicides are planters is initial cost, but they do have the advantage
currently the most reliable option for grain sorghum in that they can be used to plant other crops such as corn
the absence of cultivation. Postemergence herbicide or soybeans in narrow rows.
selection and timing should not be different than those
used in wide rows.
Crop Management Summary
Crop management machinery includes sprayers and Narrow rows have the ability to produce higher
row-crop cultivators. A row-crop cultivator may not be yields than conventional row spacings in highly pro-
an option for most row spacings less than 15 inches. ductive environments and later planting dates while not
Some growers with 20-inch rows are still cultivating. exposing producers to additional risk in more marginal
Cultivating 20-inch rows will require significant changes environments. Sorghum producers should not alter
in the cultivator and possibly tractor tire setup and width. seeding rates when converting to narrow rows because
Applying post emergence herbicides on narrow-row of sorghums ability to adjust head number and seed
grain sorghum with a ground applicator may present number per plant. Producers should choose high
challenges. It is possible to drive between 20-inch rows, yielding hybrids with exceptional standability, stalk rot
but narrower rows will be a problem. Consider spraying resistance and stay green ratings to reduce the risk of
perpendicular to the planted rows in a crop planted with lodging. Sorghum planted in narrow rows can reduce
a drill or 15-inch planter. If you are considering this weed competition. A chemical weed control program
option, use the widest possible boom since a wider should rely on preplant or preemergence soil herbicide
boom will maximize the area sprayed compared to the applications followed by an early postemergence
area being driven over. A high clearance sprayer with herbicide application if needed.
18.4-inch tires will drive on 10 percent of the area
sprayed when the sprayer is equipped with a 30-foot Related K-State Research and Extension Publications
wide boom. A sprayer with the same tire setup and a Publication Title Publication Number
60-foot boom will only drive on 5 percent of the area Grain Sorghum Production Handbook. ........................ C-687
Management of Urea Fertilizers. .................................. NCR-326
being treated. Most postemergence herbicide labeled Management Practices Affecting
for sorghum have an 8 to 12-inch plant height restric- Nitrogen Losses from Urea. ....................................... MF-984
tion, limiting most application to the early portion of Grain Sorghum Residue ................................................ L-782
the growing season. Any plant damage from tire traffic Phosphorous Facts. ....................................................... C-665
Chemical Weed Control for Field
will have little or no effect on final grain yields due to Crops, Pastures, Rangeland, and Noncropland. ........ SRP-777
sorghum’s ability to compensate by increasing head High Population, Narrow Row Dryland
number or seed number per plant in the trafficked areas. Sorghum for Southwest Kansas. ................................ KUWR-62
Super Thick Sorghum Management. ............................ SRP-437
If you are accustomed to harvesting sorghum with a row- Scott Staggenborg
crop head, expect some changes when converting to or Extension Specialist, Crops and Soils, Northeast
trying narrow-row sorghum. A grain platform with harvest Barney Gordon
attachments can be very effective in standing sorghum. Agronomist-In-Charge, North Central Kansas and Irrigation Exp. Fld.
The attachments are fixed to the cutter bar and extend Randy Taylor
forward to help keep heads from falling out of the header. Extension Specialist, Machinery and Farm Power
Attachments are available from several manufacturers and Stewart Duncan
will greatly improve harvest efficiency in standing crops. Extension Specialist, Crops and Soils, South Central
Performance may be reduced in a lodged crop. Lodged Dale Fjell
crops can be harvested with a flex head and pick-up reel. Extension Specialist, Row Crop Production
Publications from Kansas State University are available on the World Wide Web at: http://www.oznet.ksu.edu
Contents of this publication may be freely reproduced for educational purposes. All other rights reserved. In each case, credit Scott
Staggenborg et al., Narrow-row Grain Sorghum Production in Kansas, Kansas State University, January 1999.
Kansas State University Agricultural Experiment Station and Cooperative Extension Service
MF-2388 February 1999
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File code: Crops and Soils 1-5