Chloride Research: What Have We Learned?

1. 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

2. 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

3. 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

4. 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

5. 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

6. Effect of K Source and Placement on Grain Yield of Field-Grown Corn 20 lb K2O acre-1 Younts and Musgrave 1958

7. Effect of K Source and Rate on Stalk Rot in Field-Grown Corn Younts and Musgrave 1958

8. 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)

9. Winter Wheat Grain Yield as Function of N Source Christensen et al. (1981)

10. 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

11. Take-all root rot of winter wheat was reduced by KCl in Oregon

12. 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

13. 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?

14. 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

15. Wheat and barley responded to KCl while oats did not 8 site-years in South Dakota Fixen et al. (1986)

16. Chloride fertilization increased grain corn yield in Kansas Brown County - 2000 Lamond et al. 2000

17. Chloride fertilization increased grain sorghum in Kansas Brown County- 2000 Lamond et al. 2000

18. 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

19. Summary of grain yield responses to addition of 50 kg Cl- ha-1 (Manitoba, 1989-91) Mohr

20. 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-

21. Response of Winter Wheat Cultivars to Cl- fertilization Responsive Non-responsive Lamond et al. 2000

22. Response of Spring or Durum Wheat Cultivars to Cl- Fertilization Responsive Non-responsive Grant et al. 2000

23. 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

24. KCl application reduced common root rot in barley Grant and Bailey 1994

25. KCl application reduced common root rot in wheat 1= clean and 4 = severe Mohr et al 1992

26. Cl- reduced leaf rust in winter wheat in Texas Miller reported at PPI-FAR.org

27. Application Of Cl- Decreased Leaf Diseases In Marshall Spring Wheat Septoria and tanspot leaf spot complex PPI-FAR.org

28. KCl or Tilt decreased leaf disease and increased grain yield Butte spring wheat Flandreau, SD,  1984. Fixen et al. 1986 PPI-FAR.org

29. 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

30. 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

31. Osmotic potential of winter wheat leaves as related to Cl- concentration Christensen et al. 1981

32. Cl- increased leaf relative water content and grain yield in Butte spring wheat Flandreau, SD,  1984 Fixen et al. 1986

33. Effect of K source on tissue nitrate Timm et al. 1986

34. Chloride reduced the effect of take-all on grain yield 1986-88 Grain Yield (bu/acre) Christensen et al. 1990

35. 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

36. Plant development K2SO4 KCl

37. Cl- addition increased winter wheat kernel weight Engel et al. 1994

38. Physiological Leaf Spot Physiological Leaf Spot

39. “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

40. (-3.89 X) Y = 1.01 + 39.8 exp 2 R = 0.82 0 2 4 6 8 -1 Plant Cl, g kg Leaf spots severity is strongly related to plant Cl! Redwin winter wheat 50 • 10 field locations MT • 1.0 g kg-1plant Cl • Severity increases exponentially at plant Cl < 1.0 g kg-1 40 30 Leaf spot severity, % 20 10 0 no lesions

41. -1 Plant Cl, g kg Leaf Spot Severity and Plant Cl- Kestrel winter wheat • 6 field locations in MT • Relationship expressed is similar to Redwin • Break point = 1.5 g kg-1 plant Cl 50 (-2.45 X) 40 Y = 1.67 + 64.6 exp 2 R = 0.98 30 20 Leaf spot severity, % 10 0 0 2 4 6 8

42. Chloride Deficient Leaf Spot This phenomenon is not a disease! • 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 -

43. CDC Kestrel winter wheat K2SO4 KCl

44. “Chloride deficient leaf spot syndrome”

45. Soil testing can help predict Cl response 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 Based on responsive spring wheat varieties grown at 36 locations in South Dakota.

46. Yield response in wheat (size and probability) increase as plant Cl falls below 4 g kg-1 maximum response line -1 1200 NS 800 Significant Yield deficit from max., kg ha 400 0 -400 0 2 4 6 8 10 -1 Plant Cl, g kg

47. Relationship between available Cl- and tissue Cl- in Katepwa wheat Mohr

48. 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

49. Soil test Cl- content in samples taken by Agvise Lab

50. 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