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Does Chloride Deserve My Attention?

Does Chloride Deserve My Attention?. American Society of Agronomy Annual Meeting Denver, Colorado November 4, 2003 Paul Fixen Potash & Phosphate Institute. This slide set available at: http://www.ppi-ppic.org/ppiweb/napro.nsf

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Does Chloride Deserve My Attention?

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  1. Does Chloride Deserve My Attention? American Society of Agronomy Annual Meeting Denver, Colorado November 4, 2003 Paul Fixen Potash & Phosphate Institute This slide set available at: http://www.ppi-ppic.org/ppiweb/napro.nsf Additional Cl information at: www.ppi-ppic.org/chloride/index.html

  2. Related questions • Can Cl significantly influence crop growth and development? • Chemical and nutritional basics • Does Cl influence the crops I manage? • Crop sensitivity for deficiency and toxicity • Is Cl an important factor in my trade area? • Nutrient cycling • Can Cl be managed economically? • Dr. Grant and Dr. Lamond

  3. Chlorine the element One of the halogens Occurs in nature only as Cl-

  4. Chloride chemistry terminology • Chlorine (Cl): The name of the element • Chlorine gas (Cl2): A greenish yellow gas with a choking odor; used to purify municipal water • Hypochlorite (OCl-): Forms when Cl2 reacts with water; A powerful oxidizing agent sold as laundry bleach • Chloride (Cl-): The naturally occurring stable form of the element

  5. Chloride in our environment • Earth’s crust 0.15% • Seawater 1.9% • Plants 0.1-1% • Table salt 60% • Muriate of potash 47%

  6. Chloride - an essential plant nutrient • Earliest report of Cl crop response in mid 1800s in England ... NaCl (salt) topdressed to stiffen barley straw • Recognized as an essential micro- nutrient since the 1950s • Research in the late 1970s revealed insufficient levels in many areas • Phillipines, Europe, NW USA

  7. Wheat and barley responses to chloride in the Great Plains(Over 200 evaluations in KS, MN, MT, ND, SD, SK, TX) Response expressed as wheat bushels Range of response: -3 to +18 bu/A Average of all: 2.4 bu/A (includes nonresponsive varieties & high Cl sites) Frequency of significant response: 48% Average significant response: 5.2 bu/A

  8. Photosynthesis and enzyme activation Photosynthetic electron transport Due to the accumulation of Cl in chloroplasts, this biochemical need is likely always met underfield conditions Roles of chloride in plants • Stomatal operation • Transport of other nutrients in plants • Water movement in the cell

  9. -Cl +Cl Effects of chloride addition on plants • Accelerated plant development • Disease suppression/enhanced host tolerance • Increased kernel size or plumpness • Reduced late season lodging

  10. Powdery Mildew Septoria Common root rot Take-all Tanspot Leaf rust Stripe rust Spot blotch Wheat, barley and millet diseases suppressed by chloride addition

  11. Tanspot and Septoria suppresion on flag leaves of Marshall spring wheat near Watertown, South Dakota in 1985 56 lb Cl/A No Cl (Septoria and tanspot incited by Septoria avenae f. sp. triticea and Pyrenophora tritiic-repentis)

  12. Leaf rust suppression on flag leaves of winter wheat in Bosque county Texas Pioneer 2158 at anthesis. NH4Cl applied at 40 lbs Cl/A     Miller, Texas A&M Univ.

  13. Other diseases suppressed by chloride addition Corn Stalk rot Potatoes Hollow heart, Brown center Celery Fusarium yellows Coconut palm Gray leafspot Rice Stem rot, Sheath blight

  14. Mechanism of disease effects • Suppression of pathogen • Increased NH4+ uptake – rhizosphere acidification – competitive disadvantage for root pathogens • Increased Mn availability • Reduced plant NO3- concentrations • Increased leaf turgor potential • Enhanced host tolerance • Increased plant turgor reduces the effect of the pathogen on crop yield

  15. Leaf blade collar Chloride accumulates in most plants 20 fold range in plant concentration

  16. Soybean Grape Shows first on older leaves, then works its way up the plant Marginal necrosis caused by spraying Mg or NaCl to prevent stem necrosis Droughted appearance and pale green marginal necrosis Fall soil Cl >60 ppm, leaf > 0.9% Cl for susceptible cultivars (Univ. GA) Chloride toxicity Grundon, Univ. of Queensland; Gartel, Germany

  17. Toxic effects of chloride • Some plants are sensitive to Cl excesses: • Some tree, vine, citrus, vegetable, conifer, and ornamental plants • Tobacco • Certain soybean varieties grown in the SE U.S. • Conditions where excesses may occur: • Low-lying poorly drained areas • Where high water tables occur • Confined soils - greenhouses • High Cl irrigation water

  18. Cl deficient leaf spot syndrome • Leaf spot of previously unknown origin • First observed in 1991 on Redwin and Manning winter wheat in Montana • Appears similar to tanspot disease but is not caused by a microorganism • Occurs when wheat tissue Cl < 0.1% and soil Cl < 10 lb/A (0-24”) • Barley flag leaf Cl < 0.09% (Oregon State Univ.) • Not shown by all varieties that are Cl deficient • No distinctive deficiency symptoms for all varieties

  19. Cl deficient leaf spot syndrome in CDC Kestrel winter wheat No Cl 20 lb Cl/A F F-1 F-2 F F-1 F-2 Engel et al., Montana State University

  20. Cl deficient leaf spot syndromein winter wheat at mild stage (left) 20 lbs Cl/A Engel, Montana State University

  21. Cl deficient leaf spot syndromeon durum grown hydroponically in a growth room Western Plant Breeders 881 durum (WB881) Engel, Montana State University

  22. Bromide does not substitute for chloride WB881 Durum Engel, Montana State University

  23. Winter wheat Spring wheat Durum wheat Barley Corn Grain sorghum Potatoes Rice Pearl millet Coconut palm Celery Crops known to respond positively to Cl in the field

  24. Chloride cycling in agroecosystems • Sources of Cl • Wet deposition • Muriate of potash fertilizer (47%) • Manure • Irrigation water • Losses of Cl • Crop removal • Leaching

  25. Cl, kg/ha Chloride ion wet deposition 2000 2001 2002

  26. Percent of Soils Testing Medium or Lower in K in 2001 North America 43%

  27. Soil chloride levels in the Northern Great Plains 52.5% < 30 lb/A 10,324 samples collected in 1995 AGVISE Laboratories (Northwood, ND)

  28. Soil samples with chloride < 30 lb/a MB Fall 2002 Samples 65% (0-24” samples) 56% 53% 13% 55% 54% 10% 19% 82% 44% 51% 30% 14% ND 47% 77% 28% 35% 78% 63 38% MN 54% 64% SD 61% 89%

  29. Cl in Oklahoma soils 200 sample pairs from 17 counties collected from June to September, 1999 Oklahoma State Univ.

  30. Chloride removal by crops Crop Plant part Cl content Alfalfa Shoot 7.6 lb/ton Barley Grain 0.024 lb/bu Wheat Grain 0.026 lb/bu Potatoes Tubers 0.06 lb/cwt

  31. Summary: Does Cl deserve my attention? • Where K fertilization is minimal • In non-coastal areas • Where fungal disease pressure is high • For responsive crops: wheat, barley, corn, sorghum • For crops sensitive to toxicity growing where soil accumulation is likely • Where soil and plant analyses indicates low levels or unusually high levels

  32. It probably deserves more attention than its getting

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