Cropping Systems

Tillage Systems

Grain sorghum needs a warm, moist soil that is well-supplied with air and fine enough to provide good seed-soil contact for rapid germination. Farmers can use a number of different tillage and planting systems to achieve these conditions. These systems may involve primary tillage, secondary tillage or no-tillage operations prior to planting.

Any seedbed preparation should provide a means of profitable crop production while minimizing soil erosion due to wind and water. Conservation tillage systems, such as reduced till, mulch till, ecofallow, strip till, ridge till, zero till and no-till, provide protection from erosion. These systems also provide the additional benefits of moisture, energy, labor and equipment conservation.

 

 

For successful dryland sorghum, the soil profile must have stored as much precipitation as possible. In addition, runoff from high-intensity rainfall events can be greatly reduced by maintaining residue on the soil surface. Every time the soil is tilled, some moisture is lost.

Strip till resembles both no-till and minimum tillage systems and allows for the use of anhydrous ammonia, the least expensive nitrogen fertilizer. Small strips, generally a width of 8 inches or less, are tilled and fertilizer is applied below where the seed is planted. Strip till is more like traditional tillage, where the residue is removed and the seed is planted into a clean soil surface. However, similar to no-till, the residue between the strips remains. For dryland grain sorghum production, strip till could be a good intermediate step for a farmer who does not want to switch to no-till.

No-till grain sorghum planting is best suited for moderately drained and well-drained soils. Many growers find it easier to plant in standing stubble rather than in stubble lying on the ground following reduced tillage. Soils often remain cooler and wetter through the growing season under no-till conditions, which is particularly true in heavy residue. While wetter soils are an advantage during dry periods, wetter soils at planting time can require that planting be delayed to allow soils to warm up, resulting in reduced yields, particularly in cool, wet springs and on poorly drained soils. Other conservation tillage systems, such as reduced till or strip till, may be better choices in those conditions.

Crop Rotations

Wheat/Sorghum/Fallow

The wheat/sorghum/fallow rotation accounts for the greatest percentage of crop rotations in the Great Plains. The rotation results in two crops over a three-year period with a fallow period of approximately 11 months prior to the planting of each crop. This rotation allows for maximum capture of precipitation into the soil profile, which is particularly valuable to dryland sorghum in low-rainfall areas.

A 10-year study from 1984 to 1993 conducted by the U.S. Department of Agriculture-Agricultural Research Service near Amarillo, Texas, compared continuous wheat (WW), continuous sorghum (SS), wheat/fallow/wheat (WFW) and wheat/sorghum/fallow (WSF). Although this older study was conducted with lower wheat and sorghum yields than would be expected today, the relationships between rotations remain relevant.

 

Reference : Ordie R. Jones, Grant L. Johnson. A ten year comparison of cropping and tillage systems for dryland grain production. USDA-ARS Report Number 96-04.

Crop Rotation Effect on Growing Season Evapotranspiration and Overall Precipitation Use Efficiency

 Rotation

Growing Season

Fallow (Noncrop)

 Total Water

 ET1

 Grain Yield

 PUE3

 

 ET1

 Precip.

Harvest to Harvest2

Percentage of Total Water

 

 

 

Inches

Inches

Inches

%

bu/ac

bu/ac

CW

12.6

8.6

20.2

62

13.2

0.65

CS

14.1

8.9

20.7

68

42.1

2.03

WF

14.5

29.0

40.7

36

21.4

0.52

WSF/Wheat

14.3

18.8

30.4

47

22.9

0.75

WSF/Sorghum

14.8

18.9

30.6

48

56.1

1.83

 1.ET = Evapotranspiration - (soil water at planting - soil water at harvest) + growing season precipitation. 2 Harvest to Harvest = 12 months for CW and CS, 24 months for WF , 16 months for WSF/sorghum and 20 months for WSF/wheat. 3PUE = Precipitation Use Efficiency = Grain yield divided by total water available to system from harvest to harvest. 

Not surprisingly, grain yield of both grain sorghum and wheat were higher in the wheat/sorghum/fallow rotation than when either crop was grown in a continuous system. However, a crop was only harvested two out of three years. On an annual basis, more grain was produced in the continuous sorghum system (see graph below).  

 

 

 

Four Year Sorghum Wheat Rotations

A 10-year study was completed in 2015 that examined two four-year winter wheat and grain sorghum rotations. The study consisted of three crop rotations: continuous annual wheat (WW), wheat/wheat/sorghum/fallow (WWSF) and wheat/sorghum/sorghum/fallow (WSSF).

When sorghum followed wheat in the rotations, yield was 78 bushels per acre compared to 49 bushels per acre when sorghum following sorghum. The difference was a 58 percent increase in yield.

Reference: Schlegel, A. et al. Yield and soil water in three dryland wheat and grain sorghum rotations. Agron. J. 109:227-238 (2017).

Average Sorghum and Wheat Yield in Rotations From 1996 to 2015 at Tribune, Kansas

 

Grain Sorghum

Winter Wheat

Average for Rotation

Rotation

After Wheat

After Sorghum

After Wheat

After Fallow

Sorghum

Wheat

 

Average Grain Yield, bu/ac

WW

 

 

22.8

 

 

22.8

WWSF

78.3

 

28.9

36.0

78.3

32.4

WSSF

78.0

49.4

 

38.4

63.6

38.4

 

 

 

 

 

 

 

Water use efficiency of sorghum in the rotations also was improved when following wheat, increasing from 179 pounds per acre with 1 inch of water when sorghum followed sorghum to approximately 268 pounds per acre with 1 inch of water when sorghum followed wheat.

Average Water Use and Water Use Efficiency for Sorghum and Wheat in Rotations From 1996 to 2015 at Tribune, Kansas

 

Grain Sorghum

Winter Wheat

Average for Rotation

Rotation

After Wheat

After Sorghum

After Wheat

After Fallow

Sorghum

Wheat

 

Inches

WW

 

 

14.1

 

 

14.1

WWSF

15.2

 

14.6

17.6

15.2

16.1

WSSF

15.3

14.1

 

18.0

14.7

17.8

 

 

 

 

 

 

 

 

Water Use Efficiency

 

 

 

lbs/ac-inch

 

 

WW

 

 

86.1

 

 

 

WWSF

270

 

104.3

115.6

 

 

WSSF

265

179

 

120.2

 

 

 

 

Cotton/Sorghum

Sorghum works especially well in a rotation with cotton. Lint yields typically increase when following sorghum. Sorghum breaks up soil disease cycles, such as verticillium wilt, and the crop residue increases soil moisture storage by reducing water runoff and protects emerging cotton from wind damage, as illustrated in a trial conducted by Texas AgriLife near Plainview, Texas, in 2017.

In a wet year, under dryland conditions, cotton following sorghum yielded 26.5 percent higher than continuous cotton. Under limited irrigation, lint yields were over 50 percent higher than continuous cotton. Although water runoff in the continuous cotton plots due to an increase in slope contributed to part of the yield differences, sorghum residue can be attributed to at least some of the difference. 

 

Lint Yield of Cotton Cropping Systems in 2017
1.Irrigation Level Rotation Tillage Lint Yield, lb/2ac*
Dryland Continuous Cotton Conventional 648 c
Cotton/ Sorghum 820 b
Cotton/Wheat 983 a
1.5 inches  Continuous Cotton Conventional 757 c
No-till 696 c
 Cotton/Sorghum Conventional 1071 b
No-till 1200 a
 Cotton/Wheat Conventional 1106 a
No- till 1164 ab
3.5 inches  Continuous Cotton Conventional 919 b
No-till 781 b
 Cotton/ Sorghum Conventional  1342 a
No-till 1277 a
 Cotton/Wheat Conventional 1364 a
No-till 1246 a
5.0 inches  Continuous Cotton   Conventional 937 cd
No-till 921 d
 Cotton/ Sorghum Conventional 1367 a
No-till 1177 b
 Cotton/ Wheat  Conventional 1143 b
No-till 1069 bc

 

 

1Means within irrigation level with the same letter are not different at P < 0.05. Under dryland, only conventional tillage was used.
2Rainfall was above average for the year, resulting in no increase in lint yield above the 3.5 inches irrigation level.

Reference: Rothlisberger-Lewis, Katie. Integrated Grain Sorghum Production in a Cotton/Sorghum Rotation: Irrigation, Tillage and Weed Management in the Southern High Plains of Texas. Texas Grain Sorghum Producers Board Report. 2017.

 

Corn/Sorghum

Corn and sorghum are complementary warm-season grasses at many levels :

  • Sorghum and corn share almost no common diseases. Crops struggling with issues such as Goss’ wilt, a bacterial disease related to short corn rotations, and extended diapause corn rootworm can break these disease and insect cycles while still maintaining a high proportion of warm-season grasses in a rotation.
  • Sorghum is normally planted later than corn, spreading the workload and equipment over two windows for increased efficiency. Farmers could achieve this same efficiency by simply planting sorghum in one-half of the fields designated for corn rather than changing the rotation design.

 In northern areas, sorghum is most commonly planted first in the sequence, followed by corn. Reasons for this include:

  • More short-residual herbicides are available for use in corn than in sorghum.
  • Sorghum does a better job of catching snow and provides a seedbed conducive for planting corn.
  • Sorghum can struggle when seeded into heavy corn residue in northern areas due to the shorter growing season and cooler temperatures.

An Oklahoma State University trial has shown a benefit to corn yields when following sorghum. Corn grain yields were over 18 percent higher when following sorghum compared to continuous corn. Similar yield results occurred when corn was rotated with soybean. 

 

Corn Yield Following Grain Sorghum or Soybean in a Crop Rotation Study at Goodwell, Oklahoma

Rotation

2001

2002

2004

3-year

Yield, bu/ac

Soybean/Corn

137.8 (30.6)

166.7 (14.4)

209.3 (16.7)

171.3

Sorghum/Corn

143.2 (35.7)

163.9 (12.5)

202.1 (12.5)

169.7

Continuous Corn

105.5

145.7

179.6

143.6

Mean

125.5

155.5

189.2

161.5

CV%

16.7

8.2

10.2

7.6

L.S.D.

NS

20.3

NS

10.4

 Note: Number in parentheses indicates yield increase percentage as compared to continuous corn.

 

Sorghum yields were not affected in a rotation with corn or soybean when compared to continuous sorghum. 

Grain Sorghum Yield Following Soybean or Corn at Goodwell

Rotation

2001

2002

2004

Average

Yield, bu/ac

Continuous Sorghum

102.7

147.5

134.7

124.2

Soybean/Sorghum

119.2

163.1

110.9

128.1

Corn/Sorghum

105.1

139.6

116.9

120.2

Reference: Kochenower, Rick. Utilizing Grain Sorghum in Irrigated Crop Rotations. Oklahoma State.

 

In a more recent study, Dr. Allen Schlegel at the Kansas State University Agricultural Experiment Station near Tribune, Kansas, reported an 8.4 percent increase in corn yields following sorghum in a five-year study where continuous corn and continuous sorghum were compared to corn/sorghum and corn/wheat rotations. Sorghum yields improved 6.7 percent over continuous sorghum when rotated with corn.

 

Grain Yields of Three Crops Under Limited Irrigation As Affected by Rotation Across Years 2013-2017

Rotation

Corn

Wheat

Sorghum

 

Yield, bu/ac

Continuous Corn

167

 

 

Continuous Sorghum

 

 

134

Corn/Wheat

189

51

 

Corn/Sorghum

181

 

143

LSD = 0.05

16

 

6

Reference: Schlegel, A. Alternative Cropping Systems with Limited Irrigation. Southwest Research -Extension Center Field Day Report 2018.

 

Soybean/Sorghum

Soybean yield has been shown to be higher when following sorghum compared to continuous soybean in the Midsouth. Yield of soybean was 8.3 bushels per acre higher when rotated with sorghum compared to continuous soybean in a multiyear trial conducted near Stoneville, Mississippi, by the U.S. Department of Agriculture-Agricultural Research Service. In a four-year Nebraska trial, soybean yield was 16.6 percent higher than continuous soybean.

Higher soybean yield for soybean following sorghum has been attributed to one or more of the following:

  • Increased soil fertility
  • Improved soil physical properties
  • Better weed control
  • Less disease, nematode and insect pests

Nematodes can be a significant pest in continuous soybean. Rotating with sorghum can help reduce nematode populations, particularly soybean cyst, root knot and reniform species.

  

Nematode Species

Soybean

Grain Sorghum

Soybean Cyst

Host

Nonhost

Root Knot

Host

Nonhost

Reniform

Host

Nonhost

Columbia Lance

Host

Host

Lesion

Host

Host

Sting

Host

Host

 

 

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