Chloride Research: What Have We Learned?
C. A. Grant1, R. E. Lamond2 , R. M. Mohr1 and R. E. Engel3
1AAFC - Brandon Research Centre 2Kansas State University
3Montana State University
History of Chloride
• Discovered in Sweden in 1774 by Carl Wilhelm Scheele
• Present in many salts, including KCl, CaCl2 and NaCl
• Recognized as fertilizer as far back as mid 1800’s
• NaCl applied to “stiffen straw”
• Cl- viewed as active ingredient
History of Chloride • Chloride recognised as an essential
nutrient in 1954
• Required in very small amounts for crop growth (~100 mg kg-1)
• Deficiency induced in nutrient solutions
• Cl- widespread in soil and water
• Responses considered unlikely in field
What Does Cl-
Deficiency Look Like?
• Premature wilting
• Chlorosis of newly emerging leaves
• Reduced shoot and root growth
• Roots may show “herring bone” pattern
• Leaf cupping may occur
Field responses occurred where Cl- was above biochemical needs
• Late 1950’s to early 1960’s
• Sugar beets in Manitoba (Soper)
• Corn in US (Younts and Musgrave)
• Increased yield and reduced stalk rot
Effect of K Source and Placement on Grain Yield of Field-Grown Corn
0
5
10
15
20
25
30
35
40
45
Yie
ld (
bu
ac
re-1
)
Control KCl K2SO4
None
In-Row
Broadcast
20 lb K2O acre-1
Younts and Musgrave 1958
Effect of K Source and Rate on Stalk Rot in Field-Grown Corn
12
14
16
18
20
22
24
0 20 60 80 100
K Rate (lb K2O acre-1)
Sta
lk R
ot
(%) KCl
K2SO4
Younts and Musgrave 1958
Field responses occurred where Cl- was above biochemical needs
• Early 1970’s
• Coconut and other plantation crops in Philippines (von Uexkull)
• Late 1970’s - early 1980’s
• Winter wheat in Europe (Russell) and USA (Powelson and Jackson; Taylor and Christenson)
Winter Wheat Grain Yield as Function of N Source
0
1
2
3
4
5
6
7
8
Gra
in Y
ield
(T
ha
-1)
Site A Site B
(NH4)2SO4
NH4Cl
Ca(NO3)2
Christensen et al. (1981)
Reponses Not Due to “Biochemical” Deficiency
• Water relations?• Effects on plant development?• Nitrification inhibitor?• Transport of other nutrients in plant?• Reducing late season lodging?• Kernel weight?• Disease effects?
Response occurs at Cl- much higher than measured essential level
Take-all root rot of winter wheat was reduced by KCl in Oregon
Oregon results triggered interest in Cl- in Great Plains
• Responses to KCl had been noted on high K soils in Montana• Skogley and Haby (1981)• Winter wheat, spring wheat, barley,
potatoes, alfalfa and more• Suggested a problem with K soil test
prediction• Cl- response could be part of the
reason
Great Plains Research
• Will crops on the Great Plains respond to Cl-?
• Which crops will respond?
• What is the mechanism for Cl- response?
• Can we predict where responses will occur?
Cl- has improved crop yields in the Great Plains
• Over 210 trials in KS, MN, MT, ND, SD, MB and SK have evaluated Cl- response in wheat and barley
• Significant yield response in 48% of trials
• Average response of ~5 bu/A
• Cl- responses also occurred in other crops
Wheat and barley responded to KCl while oats did not
2.0
2.5
3.0
3.5
4.0
Gra
in Y
ield
(M
g h
a-1
)
Wheat Barley Oats
0 KCl
187 KCl
Fixen et al. (1986)
8 site-years in South Dakota
Chloride fertilization increased grain corn yield in Kansas
82
84
86
88
90
92
94
96
Gra
in Y
ield
(b
u a
cre-1
)
Control KCl NaCl CaCl2
20 Cl
40 Cl
Lamond et al. 2000
Brown County - 2000
Chloride fertilization increased grain sorghum in Kansas
80
82
84
86
88
90
92
94
96
98
100
Gra
in Y
ield
(b
u a
cre-1)
Control KCl NaCl CaCl2
20 Cl
40 Cl
Lamond et al. 2000
Brown County- 2000
Responses to Cl- are cultivar dependant
• Cultivar differences occur in barley and wheat
• Both spring and winter wheat
• Some of the differences may be due to disease susceptibility
Summary of grain yield responses to addition of 50 kg Cl- ha-1 (Manitoba, 1989-91)
Average Yield Response
(Kg ha-1)
Cultivar Sites with yield increase
Responsive sites
All sites
Katepwa 0 of 8 -- -10
Katepwa 0 of 4 -- -16
Roblin 1 of 4 493 137
Biggar 2 of 4 333 150
Marshall 2 of 4 363 116
Mohr
Chloride Variety Trials
• North American Cl- study
• Texas, Kansas, South Dakota, North Dakota and Manitoba
• 15 winter wheat or spring wheat varieties at each location
• Treatments: 0 Cl- and 40 lb/A Cl-
Response of Winter Wheat Cultivars to Cl- fertilization
Lamond et al. 2000
0
2
4
6
8
10
12
Yie
ld R
esp
on
se
(bu
acre
-1)
Responsive
Non-responsive
Response of Spring or Durum Wheat Cultivars to Cl- Fertilization
Grant et al. 2000
0
1
2
3
4
5
6
7
Yie
ld R
esp
on
se
(b
u a
cre
-1)
Responsive
Non-responsive
Yield Increase May Be Due To Disease Suppression
• Wheat: take-all root rot, common root rot, fusarium root rot, stripe rust, leaf rust, septoria, tanspot
• Barley: common root rot, fusarium root rot, spot blotch
• Corn: stalk rot
KCl application reduced common root rot in barley
60
65
70
75
80
85
90
95
Ro
ot
Ro
t R
ati
ng
(%
)
Control KCl KNO3 CaCl2
Grant and Bailey 1994
KCl application reduced common root rot in wheat
0.0
0.5
1.0
1.5
2.0
2.5
Ro
ot
Ro
t R
ati
ng
Carman Portage
0 Cl
50 Cl
1= clean and 4 = severe
Mohr et al 1992
Cl- reduced leaf rust in winter wheat in Texas
Miller reported at PPI-FAR.org
Application Of Cl- Decreased Leaf Diseases In Marshall Spring Wheat
Septoria and tanspot leaf spot complex
PPI-FAR.org
KCl or Tilt decreased leaf disease and increased grain yield
Fixen et al. 1986 PPI-FAR.org
Flandreau, SD, 1984.Butte spring wheat
Why Would Cl- Decrease Disease Problems?
• Increased water potential restricts infection by pathogens?
• Plants are better able to withstand disease?
• Lowers tissue NO3- which inhibits
crop susceptibility?• Increases soil NH4
+ which inhibits pathogens?• Nitrification inhibition
Oregon Studies Associated Cl- Effect With Plant Water Potential
• Cl- treated plants were more erect at mid-day
• Cl- might affect water potential
• Increased water potential may reduce susceptibility to disease
Osmotic potential of winter wheat leaves as related to Cl- concentration
-22
-21
-20
-19
-18
0.0 0.2 0.4 0.6 0.8 1.0
Chloride Concentration (%)
Os
mo
tic
Po
ten
tia
l (b
ars
)
Christensen et al. 1981
Cl- increased leaf relative water content and grain yield in Butte spring wheat
Fixen et al. 1986
Flandreau, SD, 1984
Effect of K source on tissue nitrate
0.0
0.5
1.0
1.5
2.0
Tis
sue
NO
3-N
at
Bo
ot
(g/k
g)
Carringto
n
Fortuna
Minot
Powers L
ake
Willi
ston
Control
K2SO4
KCl
Timm et al. 1986
Chloride reduced the effect of take-all on grain yield
Christensen et al. 1990
1986-88
Gra
in Y
ield
(b
u/a
cre
)
Cl- Sometimes Increased Yield Without Affecting Disease
• Enhanced crop development
• Higher kernel weight
• Longer grain fill
• Greater rate of kernel growth
• Better water relations
• Reduced lodging
KK22SOSO44 KClKCl
Plant development
Cl- addition increased winter wheat kernel weight
15
20
25
30
35
40
45
10
00
Ke
rne
l W
eig
ht
(g)
1 3 4 5 6 7 8 9
Site
- Cl
+ Cl
Engel et al. 1994
Physiological Leaf Spot Physiological Leaf Spot
“Physiological Leaf Spot”
• Occurs in winter and durum wheat
• Recently reported in barley
• Looks similar to tanspot disease
• Related to crop genetics
• Redwin, Sierra, CDC Kestrel are susceptible
0
10
20
30
40
50
0 2 4 6 8
Plant Cl, g kg-1
Leaf
sp
ot
severi
ty,
%
Y = 1.01 + 39.8 expY = 1.01 + 39.8 exp
(-3.89 X)(-3.89 X)
22RR = 0.82= 0.82
Leaf spots severity is strongly related to plant Cl!
Redwin winter wheat
• 10 field locations MT
• 1.0 g kg-1 plant Cl
• Severity increases exponentially at plant Cl < 1.0 g kg-1 no lesions
Leaf Spot Severity and Plant Cl-
• 6 field locations in MT
• Relationship expressed is similar to Redwin
• Break point = 1.5 g kg-1 plant Cl
Kestrel winter wheat
0
10
20
30
40
50
0 2 4 6 8
Plant Cl, g kg-1
Leaf
sp
ot
severi
ty,
%
Y = 1.67 + 64.6 exp Y = 1.67 + 64.6 exp (-2.45 X)(-2.45 X)
RR22 = 0.98= 0.98
This phenomenon is not a disease !
Chloride Deficient Leaf Spot
• Applications of fungicides have no effect on symptoms
• There is no infectious organism on affected tissue
• Symptoms can be reproduced in solution culture
WB881 durum wheat
- 0 Cl dose -
CDC Kestrel winter CDC Kestrel winter wheatwheat
KK22SOSO44 KClKCl
“Chloride deficient leaf spot syndrome”
Soil testing can help predict Cl response
Based on responsive spring wheat varieties grown Based on responsive spring wheat varieties grown at 36 locations in South Dakota. at 36 locations in South Dakota.
Response
Category Soil Cl Frequency Average
lb/A-2 ft % bu/A
Low < 30 69 4.0
Medium 31- 60 31 2.6
High > 60 0 0.3
-400-400
00
400400
800800
12001200
00 22 44 66 88 1010
Plant Cl, g kgPlant Cl, g kg-1 -1
Yie
ld d
efici
t fr
om
max.,
kg h
aYie
ld d
efici
t fr
om
max.,
kg h
a-1
-1 maximum response linemaximum response line
NS
Significant
Yield response in wheat (size and probability) increase as plant Cl falls below 4 g kg-1
Relationship between available Cl-
and tissue Cl- in Katepwa wheat
R2 = 0.68
R2 = 0.73
0
2
4
6
8
10
0 20 40 60 80 100
Soil (to 60 cm) + Fertilizer Cl (kg ha-1)
Pla
nt
Cl
Co
nc
en
tra
tio
n (
g k
g-1
)
KCl
NaCl
Mohr
Soil test recommendations vary with region
• Montana, North Dakota and Manitoba
• Soil Cl to 24” + fertilizer should equal 30 lb Cl- acre-1
• Saskatchewan
• Apply if soil Cl- to 12” is below 16 lb acre-1
Soil test Cl- content in samples taken by Agvise Lab
Low Soil Cl- Does Not Guarantee a Reponse
• Cultivar effects
• Disease pressure
• Moisture regime
• Other stress effects
Soil testing identifies sites where responses are more likely to occur
What Have We Learned?
• Cl- responses can occur under field situations
• Not strictly a biochemical requirement
• Responses are strongly related to cultivar
What Have We Learned?
• Disease suppression plays a role• Not the sole reason for
benefits• “Physiological leaf spot” is Cl-
deficiency in susceptible cultivars• Cl- application cures the
problem
What Have We Learned?
• Other benefits occur• Kernel weight • Water relations • Lodging resistance • Crop development
• Soil testing and tissue testing can help predict responses
Questions?