Soil Solution

1
Main Cycle
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Cl- cycling in soils
Plant and Animal residues
Atmospheric
Cl-
Plant
Uptake
Primary and Secondary Cl minerals
Soil Organic matter
Soil Solution Cl-
Dissolution
Precipitation
Mineralization
Immobilization
Adsorption
Adsorbed or labile Cl-
Desorption
Leaching
2
Main Cycle
More Info
Cl- cycling in soils
Plant and Animal residues
Atmospheric
Cl-
Plant
Uptake
Primary and Secondary Cl minerals
Soil Organic matter
Soil Solution Cl-
Dissolution
Precipitation
Mineralization
Immobilization
Adsorption
Adsorbed or labile Cl-
Desorption
Leaching
3
Main Cycle
More Info
Cl- cycling in soils
Plant and Animal residues
Atmospheric
Cl-
Plant
Uptake
Primary and Secondary Cl minerals
Soil Organic matter
Soil Solution Cl-
Dissolution
Precipitation
Mineralization
Immobilization
Adsorption
Adsorbed or labile Cl-
Desorption
Leaching
4
Main Cycle
More Info
Cl- cycling in soils
Plant and Animal residues
Atmospheric
Cl-
Plant
Uptake
Primary and Secondary Cl minerals
Soil Organic matter
Soil Solution Cl-
Dissolution
Precipitation
Mineralization
Immobilization
Adsorption
Adsorbed or labile Cl-
Desorption
Leaching
5
Main Cycle
More Info
Cl- cycling in soils
Plant and Animal residues
Atmospheric
Cl-
Plant
Uptake
Primary and Secondary Cl minerals
Soil Organic matter
Soil Solution Cl-
Dissolution
Precipitation
Mineralization
Immobilization
Adsorption
Adsorbed or labile Cl-
Desorption
Leaching
6
More Information on Chloride
Form taken up by plants
Deficiency symptoms
Effect of pH on availability
Mobility in soil
Origins of Cl in soil and plants
Mobility in plant
Role of nutrient in plant growth
Fertilizer Sources
  Behavior in soil
Role in microbial growth
  Accumulations of Cl in soil
Interactions of Cl
  Effects
Concentration in plants
  Other
Forms in soil
  Toxicity Symptoms
Main Cycle
  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 gt7
•   Non specific adsorption pH lt7
•   No effect on availability

Main Cycle
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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 Cycle
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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

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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.
  lt70-700 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, lt2ppm.

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Main 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.

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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.

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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.
•  

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14
References

• Bohn, H.L., B.L. McNeal and G.A. OConnor. 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

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15
Links
Chloride Crop Nutrition
Nutrient Cycles
A Great Resource
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Main Cycle
16
Cl- cycling in soils
Atmospheric
17
Soils
Air Pollution CFCs
Chlorine Cycle
Ocean (sea spray)
Biomass Burning
Atmosphere
Precipitation
Volcanic Emissions
Plants Cl-
Road Salts, Feedlots, Irrigation
Water, Industrial Wastewater
Wind Erosion of Salt Evaporates
Soil NaCl MgCl2 CaCl2
Municipal Water
Parent Material
Leaching
Runoff
Plastics
Fertilizers