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Main Cycle More Info Links Cl- cycling in soils Plant and Animal residues Atmospheric ClPlant Primary and Secondary Cl minerals Dissolution Precipitation Uptake Soil Solution ClMineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching Soil Organic matter Main Cycle More Info Cl- cycling in soils Plant and Animal residues Atmospheric ClPlant Primary and Secondary Cl minerals Dissolution Precipitation Uptake Soil Solution ClMineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching Soil Organic matter Main Cycle More Info Cl- cycling in soils Plant and Animal residues Atmospheric ClPlant Primary and Secondary Cl minerals Dissolution Precipitation Uptake Soil Solution ClMineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching Soil Organic matter Main Cycle More Info Cl- cycling in soils Plant and Animal residues Atmospheric ClPlant Primary and Secondary Cl minerals Dissolution Precipitation Uptake Soil Solution ClMineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching Soil Organic matter Main Cycle More Info Cl- cycling in soils Plant and Animal residues Atmospheric ClPlant Primary and Secondary Cl minerals Dissolution Precipitation Uptake Soil Solution ClMineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching Soil Organic matter More Information on Chloride Form taken up by plants: Deficiency symptoms: Mobility in soil: Effect of pH on availability: Mobility in plant: Origins of Cl in soil and plants: Role of nutrient in plant growth: Fertilizer Sources: Role in microbial growth: Behavior in soil: Interactions of Cl: Accumulations of Cl in soil: Effects: Concentration in plants: Forms in soil: Main Cycle References: Other: Toxicity Symptoms: More Info. on Chloride • • • • Main Cycle Form taken up by plants ClMobility 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 More Info More Info. on Chloride • • Main Cycle 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 More Info More Info. on Chloride • • Main Cycle 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 Info More Info. on Chloride • • Main Cycle 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 Info More Info. on Chloride • • Main Cycle 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 Info More Info. on Chloride • • • Main Cycle 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 Info 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. Main Cycle More Info References Bohn, H.L., B.L. McNeal and G.A. O’Connor. 1979. Soil Chemistry, WileyInterscience, 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 Main Cycle More Info Links Chloride Crop Nutrition Nutrient Cycles Main Cycle More Info **A Great Resource** Chlorine Cycle Air pollution Atmosphere Ocean CH3 Cl Dry fallout Cl2 CFC’s (Sea Spray) Cl- cycling in soils Atmospheric Biomass Burning Volcanic emissions HClO Precipitation Plants Road salts, Feedlots, Irrigation water Industrial wastewater ClWind erosion of salt evaporates Soil Municipal water NaCl (Drinking + Swimming) Parent material MgCl2 CaCl2 Negligible addition Fertilizers Plastics (PVC-polyvinyl chloride) Runoff 8 kg/ha/hr Leaching AEC only in acid soils KCl 0-0-62 47% Cl- Air Pollution CFC’s Ocean (sea spray) Chlorine Cycle Soils Atmosphere Biomass Burning Precipitation Plants Cl- Road Salts, Feedlots, Irrigation Water, Industrial Wastewater Wind Erosion of Salt Evaporates Soil Municipal Water NaCl MgCl2 CaCl2 Runoff Plastics Volcanic Emissions Parent Material Leaching Fertilizers