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Grain Sorghum Management under Limited Irrigation

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2

Risk Management in Sorghum

• Important Decisions

– Hybrid selection

– Planting

date/Maturity

– Water supply

– Seeding rate

– Weed control

– Soil Fertility

– Pest Management


3

Limited Irrigation Goals

• Allocate limited resources to maximize returns

– Drought tolerant crops?

• Wheat or sorghum?

– Cropping system on the acre?

• Irrigated / Dryland crop mixture

– Critical growth stages?

• Not every inch of irrigation is equal when it comes to timing.

3


4

Drought Tolerant Crops?

-50

0

50

100

150

200

4.0 8.0 12.0 16.0 20.0 24.0 28.0

Water Use (in)

Gra

in Y

ield

(b

u/a

)

Grain Sorghum - 9 bu/in

Soybean - 5.2 bu/in

Corn - 11 bu/in

Wheat - 6.5 bu/in

L.R. Stone


5

Environments with a wide range of water

Years

1992 through 2011


6

Sorghum and Corn Yields

0

50

100

150

200

250

300

0 50 100 150 200 250 300

So

rgh

um

Yie

ld, b

u/a

Corn Yield, bu/a


7SC Kansas Rainfed

Category Corn Sorghum

Yield (bu/acre) 110 110

Price per bu 5.68 5.58

Gov’t Payment 16.58 16.58

Total Revenue 641.38 630.39

Seed 66.47 12.58

Herbicides 28.16 18.48

Insect/Fungicides 1.00 0.00

Fertilizer 85.00 94.20

Consult/Dry/Ins. 0.00 0.00

Machinery 116.76 114.02

Non Machinery

Labor

13.19 12.88

Land Rent 74.40 74.40

Total 391.54 332.31

Return over Costs 249.84 298.07

NE Kansas Rainfed

Category Corn Sorghum

Yield (bu/acre) 160 130

Price per bu 5.68 5.58

Gov’t Payment 14.68 14.68

Total Revenue 923.49 740.09

Seed 87.48 16.01

Herbicides 30.00 30.58

Insect/Fungicides 26.55 0.00

Fertilizer 110.56 72.80

Consult/Dry/Ins. 17.29 11.70

Machinery 98.86 87.02

Non Machinery

Labor

11.17 9.83

Land Rent 136.80 136.80

Total 527.46 372.99

Return over Costs 396.03 367.10


8

Economic Comparison

-800

-600

-400

-200

0

200

400

600

800

1000

0 50 100 150 200 250 300

So

rgh

um

Ad

van

tag

e,

$/a

Corn Yield, bu/a

Sorghum/Corn Price Ratio: 93% 100%

Corn yields where

Economic Tipping Point = 110 132 bu/a


9

Total Leaf Area

60% D.M & 70 % N

Maximum Root Depth

Panicle Differentiation

Potential Seed Number

Determined

6 32-35 32-35 32-35 15

Plant EmergePanicle

Initiation

BootPhys

Mat.Harv

GSI GSII GSIII

Total Leaf

Number

1/3 Leaf Area

1/5 Total Wt.

~ 8 Leaf Stage

Total Dry Wt.

Total Grain Wt.

Loss of Leaf

Area

Sorghum Growth, Development, and Yield

AnthesisSeed Set

Final Seed Number Set


Seed Number per Acre and Yield

y = 1.0546x - 1.4332

R2 = 0.9143

0

20

40

60

80

100

120

0 20 40 60 80 100 120

Seed/a (millions)

Yie

ld (

bu

/a)


11

Limited Irrigation Sorghum Management

• Planting Date: Plant early

– You want the longest growing season you can get and

there is often little or now penalty for planting a bit early

• Hybrid Maturity: Fullest for your area

– NW KS = Medium

– SW KS = Medium Full

• Planting Rate: 70,000 seed per acre (or more)

• Row Spacing: Narrow rows might improve yields

– Never saw lower yields in narrow rows in previous studies

– Stand establishment with drills may be a challenge


12

60

80

100

120

140

160

10-May 30-May 16-Jun 30-Jun

Planting Date

Yie

ld (

bu

/A)

Early Medium Full

Sorghum Planting Date – NC Kansas


13

Limited Irrigation Sorghum Management

• Planting Date: Plant early

– You want the longest growing season you can get and

there is often little or now penalty for planting a bit early

• Hybrid Maturity: Fullest for your area

– NW KS = Medium

– SW KS = Medium Full

• Planting Rate: 70,000 seed per acre (or more)

• Row Spacing: Narrow rows might improve yields

– Never saw lower yields in narrow rows in previous studies

– Stand establishment with drills may be a challenge


14

60

80

100

120

140

160

5 10 15 20 25 30 35

Row Spacing (in)

Yie

ld (

bu

/a)

Man-95 Pow-95

Bel-95 Man-96

Bel-96

LSD = 10.4

Sorghum Row Spacing


15

Deficit Irrigation – Bushland, TX

Variable Full Irr.

50%

Deficit

Irr.

Rainfall (in) 8.3 8.3

Irrigation (in) 14.5 6.7

Total Water (in) 22.8 15.0

Crop Water

Use (in) 24.4 22.0

Yield (bu/acre) 150.2 146.5

WUE (bu/in) 5.9 6.6


16

1.3

Feet

2.6

3.9

5.2

6.6

7.9

0.0

1.3

Feet

2.6

3.9

5.2

6.6

7.9

0.0


Sorghum and Soil Moisture(Tribune, KS 1973-1987)

y = 5.0465x + 27.862

0

20

40

60

80

100

120

0 2 4 6 8 10 12

Soil Moisture at Planting (in)

So

rgh

um

Yie

ld (

bu

/a)


Irrigation Effects on Grain Sorghum Hybrids

Treatment Medium Early Full Season

Yield, bu/acre

Dryland 110 95

Boot 149 160

Mid-bloom 135 148

Boot +Mid-

bloom

162 176

Hybrid Avg 139 145


Irrigation Timing and Grain Sorghum

Time of Irrigation Yield

bu/a

Preplant only 65

Pre+Boot Stage 125

Pre+Half-Bloom 115

Pre+Soft-Dough 114

Full Season Irrigation 126

Tribune, KS


Limited Irrigation

Tribune, KS

Irrigation

Amount Corn

Grain

Sorghum Soybean Sunflower *

(in) - - - - - - - - bu/a - - - - - - - - lb/a

5 124 124 34 1725

10 169 (36) 149 (20) 41 (20) 1978

15 184 (48) 172 (39) 47 (39) 1759

() represent % increase over 5 in irrigation

* Stem borer infestation lowered sunflower yields


21

Stalk rots

• Stalk Rots in Corn and Sorghum

(KSU Pub No. L-741)

– Stalk rot is the most prevalent

disease of corn and sorghum in

Kansas. Annual losses are difficult

to determine, because unless

lodging occurs, the disease goes

mostly unnoticed. The best

estimates are that at least 5

percent of the corn and sorghum

crop are lost each year to stalk rot.


22

Stalk Rots

• Prevention– Reduce stress through late

season irrigation

– Harvest Early

– Select hybrids that have good standability ratings

– Select hybrids with the stay-green trait

– Balanced N program (avoid too much or too little)

– Maintain adequate K and Cl levels in system

– Rotate to small grains or alfalfa

• Types

– Fusarium

• Dry early and warm, wet

weather after anthesis

– Charcola Rot

• High soil temperatures

and low soil moisture

during grain fill

– Anthrachnose

• High temperatures and

humidity


23

Summary

• Consider crop mixtures or cropping systems that return the greatest $/acre. It could be that some crops get very little irrigation water.

• Plant sorghum as early as possible and potentially in narrow rows to maximize yields under limited irrigation.

• Be certain to reduce plant water stress during GS II when the panicle is developing.

• Water during grain fill will improve yields slightly, but will result in better stalk quality and less lodgeing.

• Manage lodging through hybrid selection, proper fertility and appropriate crop rotations.


24

• Questions?


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a in Sor um Manag t und Limit Irrigationsorghumpartners.com/wp...Sorghum-Management-Under-Limited-Irrigation.pdf · Limited Irrigation Sorghum Management • Plan ng Dat ? Plan rly