1. Soil Solution Cl - Primary and Secondary Cl minerals Adsorbed or labile Cl - Soil Organic matter Dissolution Precipitation Adsorption Desorption Leaching Mineralization Immobilization PlantUptake Plant and Animal residues Cl - Cl - cycling in soils Atmospheric Main CycleMore InfoLinks

2. Soil Solution Cl - Primary and Secondary Cl minerals Adsorbed or labile Cl - Soil Organic matter Dissolution Precipitation Adsorption Desorption Leaching Mineralization Immobilization PlantUptake Plant and Animal residues Cl - Cl - cycling in soils Atmospheric Main CycleMore Info

3. Soil Solution Cl - Primary and Secondary Cl minerals Adsorbed or labile Cl - Soil Organic matter Dissolution Precipitation Adsorption Desorption Leaching Mineralization Immobilization PlantUptake Plant and Animal residues Cl - Cl - cycling in soils Atmospheric Main CycleMore Info

4. Soil Solution Cl - Primary and Secondary Cl minerals Adsorbed or labile Cl - Soil Organic matter Dissolution Precipitation Adsorption Desorption Leaching Mineralization Immobilization PlantUptake Plant and Animal residues Cl - Cl - cycling in soils Atmospheric Main CycleMore Info

5. Soil Solution Cl - Primary and Secondary Cl minerals Adsorbed or labile Cl - Soil Organic matter Dissolution Precipitation Adsorption Desorption Leaching Mineralization Immobilization PlantUptake Plant and Animal residues Cl - Cl - cycling in soils Atmospheric Main CycleMore Info

6. More Information on Chloride Effect of pH on availability: Origins of Cl in soil and plants: Accumulations of Cl in soil: Form taken up by plants: Mobility in soil: Mobility in plant: Role of nutrient in plant growth: Role in microbial growth: Concentration in plants: Forms in soil: Deficiency symptoms: Interactions of Cl: Main Cycle Fertilizer Sources: Effects: Behavior in soil: Other: Toxicity Symptoms: References:

7. More Info. on Chloride Form taken up by plants Cl - Mobility in Soil Mobile Mobility in plant Mobile Effect of pH on availability: Non adsorbed at pH >7 Non specific adsorption pH <7 No effect on availability Main CycleMore Info

8. More Info. on Chloride Role of nutrient in plant growth: Stimulates splitting of water in photosynthesis, essential for roots, cell division in leaves and as an osmotically active solute. Winter Wheat: Suppresses take-all, stripe rust, tan spot. Wheat: Suppresses leaf rust and tan spot. Oats: Suppresses leaf rust Corn: Suppresses stalk rot Role in microbial growth: Unknown Main CycleMore Info

9. More Info. on Chloride Interactions with other nutrients: Uptake of NO3 and SO4 can be reduced by the competitive effects of Cl. Lower protein concentrations in winter wheat are attributed to strong competitive relationships between Cl and NO3 when Cl levels are high. Negative interaction between Cl and NO3 has been attributed to competition for carrier sites at root surfaces. Fertilizer Sources: Source %Cl Ammonium Chloride 66 Calcium Chloride 65 Potassium Chloride 47 Magnesium Chloride 74 Sodium Chloride 60 More InfoMain Cycle

10. More Info. on Chloride Concentration in plants: Normal concentration is 0.2 - 2.0 % of dry matter. Cereal grain concentrations are 10-20 ppm, sugarbeet leaves 100-200 ppm. Tobacco plants require concentrations in soil of 10-15 ppm. <70-700 ug/g in tissue is deficient. Deficiency symptoms: pH unknown. Reduced growth, wilting, development of necrotic and chlorotic spots on leaves, with leaves eventually attaining a bronze color. Roots become stunted in length but thickened or club shaped near the tips. Acts as a counter ion during rapid K+ fluxes, contributes to turgor of leaves. Deficiency occurs in soils, <2ppm. More InfoMain Cycle

11. More Info. on Chloride Behavior in Soil Cl anion is very soluble in most soils. It is rapidly cycled through soil systems due to mobility (except in extremely acid soils). Exchangeable Cl can occur in acid, kaolinitic soils which have pH dependent positive charges. In humid climate zones Cl is leached through the soil system and in Arid to Semi-arid zones it is concentrated in the soil horizon. Origins of Cl in Soil and Plants: Most Cl in soil comes from salt trapped in parent material, marine aerosols, and volcanic emissions. Most often found in apatite, hornblende, and some feldspars. Nearly all soil Cl has been in the oceans at least once and returned to land by uplift and subsequent leaching of marine sediments or by oceanic salt spray carried in rain or snow. Sea spray near coastal regions provides about 100 kg/ha/yr and for inland regions accumulations are 1-2 kg/ha/yr. For inland regions these amounts are adequate since no deficiencies have been reported. Salt droplets and dust particles can be absorbed by plant leaves in adequate amounts for plant requirements. More InfoMain Cycle

12. More Info. on Chloride Accumulations of Cl in soils: Accumulates where internal drainage of soils is restricted and in shallow groundwater where Cl can move by capillary action into the root zone and be deposited at or near the soil surface. Effects: Primary effect is an increase of osmotic pressure of soil water and thereby lowers the availability of water to plants. Forms in Soil: Most Cl exists as soluble salts of NaCl, CaCl2, or MgCl2. More InfoMain Cycle

13. More Info. on Chloride Toxicity Symptoms: pH unknown. Can reduce yield and quality of crops. High levels will increase total leaf water potential and cell sap osmotic potential in wheat. Improves moisture relations in some crops. Leaves of tobacco and potatoes become thickened and tend to roll when excessive Cl concentrations occur. Storage quality of potato tubers are adversely affected by surplus uptake of Cl. Other: In recent years water softening, industrial brines, and road deicing have contributed significant amounts of Cl to local areas. Irrigation water that is highly mineralized, salt water spills associated with extraction of oil, natural gas, some coal deposits and improper disposal of feedlot wastes can supply Cl to soil. Wind erosion of salt evaporates can also affect enrichment of soils. More InfoMain Cycle

14. References Bohn, H.L., B.L. McNeal and G.A. O’Connor. 1979. Soil Chemistry, Wiley- Interscience, New York, 219, 232, 286 pp. Pendias-Kabata, Alina and Henryk Pendias. 1992. Trace Elements in Soils and Plants. 2nd ed. CRC Press, Florida, 251-252pp. Salisbury, Frank B. and Cleon W. Ross. 1992. Plant Physiology, 4th ed. Wadsworth Inc., California, 120, 129, 133, 135, 148, 215, 217 pp. Tisdale, S.L., W.L. Nelson, J.D. Beaton and J.L. Havlin. 1993. Soil Fertility and Fertilizers. 5th ed. Macmillan, New York, 73-75, 342-344 pp. Authors: David Gay, Justin Carpenter, Mark Wood, Curt Woolfolk and J. Clemn Turner More InfoMain Cycle

15. Chloride Crop Nutrition Nutrient Cycles **A Great Resource** Links More InfoMain Cycle

16. Chlorine Cycle Atmosphere Plants Soil NaCl MgCl 2 CaCl 2 Biomass Burning Air pollution CFC’s Volcanic emissions Precipitation Ocean (Sea Spray) CH 3 Cl HCl Dry fallout Cl 2 Wind erosion of salt evaporates HCl HClO Parent material Negligible addition Fertilizers KCl 0-0-62 47% Cl - Road salts, Feedlots, Irrigation water Industrial wastewater Municipal water (Drinking + Swimming) Plastics (PVC-polyvinyl chloride) Leaching Runoff 8 kg/ha/hr Cl - AEC only in acid soils coast 100 kg/ha/yr inland 1-2 kg/ha/yr Cl - cycling in soils Atmospheric

17. Soils Plants Cl - Soil NaCl MgCl 2 CaCl 2 Air Pollution CFC’s Ocean (sea spray) Precipitation Biomass Burning Volcanic Emissions Wind Erosion of Salt Evaporates Parent Material Fertilizers Road Salts, Feedlots, Irrigation Water, Industrial Wastewater Municipal Water Plastics Chlorine Cycle LeachingRunoff Atmosphere