GYPSUM Aspirin for the Soil

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4/22/12

GYPSUM – “ASPIRIN” FORTHE SOILIts Use in the United States

Malcolm E. SumnerRegents’ Professor of Environmental SoilScience EmeritusUniversity of GeorgiaAthens, GA

[email protected]



4/22/12

INTRODUCTION

• Ancient history of gypsum use

• Gypsum use in the 20th and 21st

Centuries – Mined vs Industrial gypsum

– Agricultural benefits

• Amendment for sodicity & crusting – Promotes infiltration and permeability

• Nutrient source

–

Ca and S•



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WHAT IS FGD GYPSUM?

Scrubber

Dewateringpond

PowerPlant

CaCO3 + SO2 + H2O + O2CaSO4.2H2O

FGDGypsum

Limestone

Sulfurdioxide

Water

Oxygen

FGDGypsum

FGD = Flue gasdesulfurization



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Mined vs By-productGypsum

PURITYFGD 95.3%MINED 77.8%

P u r e

g y p s u m



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Crust Formation, Infiltration,Runoff & Erosion



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Raindrop energy

CRUST FORMATIONRequires

Dispersible clay



CRUST FORMATION

“Washed-in”

layer”

“Washed-out”layer



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CLOSEUP

Seal 1-2 mmthick



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GYPSUM

• Promotes clay flocculation

• Increases infiltration

•

Increases percolation• Reduces crusting

• Decreases runoff and erosion

• Promotes seedling emergence



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I n

f i l

t r

a t

i o

n

r a

t e

(

m

m

/ h

r )

S

o i

l

l o

s s ( T

/ h

a )

Increases infiltration

Decreases soil loss

Promotes flocculation

Reduces runoff



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Gypsum Promotes Water

Percolation



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GYPSUM PROMOTES

SEEDLING EMERGENCE



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Poor emergence due to crust



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SEEDLING EMERGENCE

•

Drying of crust• Increases strength• Germinating seedlings unable to emerge• Poor crop stand• Reduced yield

• Gypsum over row reducescrusting

• Allows seedlings to emerge



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CRUSTING ANDSEEDLING EMERGENCE

0 2 4 6 8 10 120

10

20

30

40

50

60

70

80

90

100

Dispersible clay (%)

DispersibleClay

Penetrationresistance

Seedlingemergence



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GYPSUM AND SEEDLINGEMERGENCE

0

2

4

6

8

10

12

Days after planting

Seedlin g

emergenc

e(%)

Gypsum promotes•

Seedlingemergence



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SUBSOIL HARDPANS

• Many soils have natural ortillage-induced hardpans

– Limit root penetration into subsoil

– Restrict crop’s ability to obtainwater

• Penetration resistance

– Measured by cone penetrometer

• Expressed as cone index



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Effect of Compaction on SoilPorosity



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Effect of Compactionon Root and

Top Growth of Corn

LOW MED HIG

HG



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ConePenetrometer

Effect of Gypsum on Cone



Effect of Gypsum on ConeIndex

0 2 4 6 8 10 120

2

4

6

8

10

12

Cone index (MPa)

Depth

(cm)



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GYPSUM, CONE INDEX &COTTON ROOT GROWTH

0 2 4 6 8 10 12

Effect of Subsoiling and



Effect of Subsoiling andGypsum on Infiltration

0

1

2

3

4

56

7

8

9

10

Year



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GYPSUM AS NUTRIENT

SOURCE



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Peanu

ts



PEANUTS

0

2

4

6

8

10

12

Yield(T

/ha)



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Tomatoe

s

GYPSUM AND TOMATOES



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GYPSUM AND TOMATOES- ALABAMA

0

2

4

6

8

10

12

Year

Y

ield(T

/ha)



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Shelf Life of Tomatoes(Stored at Room Temperature for 2 Weeks -

Mississippi)



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B l o s s o m e

n d

r o t



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Cantaloupes



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NoGypsum

1 TGypsum/ha

2 TGypsum/

ha

3 TGypsum/

ha

GYPSUM AND



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GYPSUM ANDCANTALOUPES

0

2

4

6

8

10

12

Yield(T

/ha)



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Cantalou

pesstored at4°C for 4

weeks

NoGypsu

m

2 T



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SQUASH

Contr Gypsu

Squash Yield Response



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Squash Yield Responseto Gypsum

0

2

4

6

8

10

12

Site #

Increas

ein

y ieldduetog

ypsum

(%)



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Cucumber

C b Yi ld



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Cucumber YieldResponse to Gypsum



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BELLPEPPERS

Eff t f G B ll



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Effect of Gypsum on BellPepper Yield

0

2

4

6

8

10

12



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Watermelon



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Gyps

um

Contr

ol

Effect of Gypsum on



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Effect of Gypsum onWatermelon Yields - Florida

0

2

4

6

8

10

12

Yield(T

/ha)



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Sunn Hemp



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CONTROL

Effect of Gypsum on Sunn



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Effect of Gypsum on SunnHemp Yield & N Uptake

0

2

4

6

8

10

12



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GYPSUM

CONTROL



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Potato

Effect of Gypsum on Potato -



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Effect of Gypsum on Potato -Florida

0

2

4

6

8

10

12

Yield(T

/ha)



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CONTROL

GYPSUM



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GYPSUM & SUBSOILACIDITY

Requirements for Good



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Requirements for GoodRoot Growth

• Absence of soluble Al3+

• High levels of soluble Ca2+

Gypsum & Reduction of



4/22/12 A l 3

+

A l 3+

A l 3+

Al3+Al3+Al3+

Al3+ Al3

Al 3 + Al 3 + Al 3 +

GypsumApplication

Al3+

Al 3 + A

Ca2+ Ca2+Ca2+ Ca2+

Ca2+ Ca2+

Crop

Gypsum & Reduction of Subsoil Acidity

• Increases subsoil calcium•

Reduces subsoil aluminum(toxic)• Allows roots to penetrate

subsoils• Increases potentially available

water



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Roots pruned

High Al and Low Ca Cause

Root Pruning



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Effect of Gypsumon Exchangeable

Al and Ca in theSoil Profile

Effect of Gypsum on



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Effect of Gypsum onExchangeable Al

Effect of Gypsum on



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Effect of Gypsum onExchangeable Ca



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Alfalfa

Effect of Gypsum on Alfalfa



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Effect of Gypsum on Alfalfa Yields



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Control

Gypsum

0 2 4 6 8 10 12Walk McCallu



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0 2 4 6 8 10 12

Increase in root growth due to gypsum (%

Depth (in)

0 2 4 6 8 10 12

Increase in root growth due to gypsum (

Depth (in)

er m



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Cotton

Root De elopment



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Contortedtap roots dueto Al toxicity

Straighttap rootsin

absence

Root Development -Mississippi

Effect of Gypsum on



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Effect of Gypsum onCotton Yield

0

2

4

6

8

10

12

Year

Lintyie

ld(kg/ h

a)



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Pastur

es

Effect of Gypsum on



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ec o Gypsu oBermuda Nutrient Content

0

2

4

6

8

10

12

Nut

rien

tconte

nt(%

)

B d d F



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Bermuda and Fescue -Georgia

0

2

4

6

8

10

12

Yield(T

/ha)

i t th d t 0 50 100

Bermuda

Fescue



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0 2 4 6 8 10 12

e in root growth due to gyps

Depth

(in)

0 50 100

crease in root growth due to

Depth (in)

a e



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Turf

East LakeCC

Lane Creek GC



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0 2 4 6 8 10 12

ase in root growth due to gyp

Dep

th(cm)

0 2 4 6 8 10 12

Increase in root growth due to g

Depth (in)

CC GC



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CONCLUSIONS

• Gypsum

– Reclaims sodic soils

– Promotes clay flocculation &infiltration

– Promotes percolation & drainage

– Reduces crusting, runoff & erosion

– Ameliorates subsoil acidity

– Softens subsoil hardpans

–

Provides a source of Ca and S for



UNIVERSITY OF

GEORGIAFirst Publically Funded University in the

United States

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GYPSUM Aspirin for the Soil