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Plant uptake as Mg2+ at root tip
Crop removal
Plant residue and Microbial population
Mineralization
Immobiliz
ation
Erosion
CEC
Leaching MgSO4
Chelates in solution
Secondary clay and humus
Weathering
PPTSoil Solution
Mg fertilizer
Mg 2+
Magnesium Cycle
Authors: Jeffrey Ball, Mark Everett, Rick Kochenower, and Heather Qualls
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Dolomite, MgSO4, MgO, Mangesite,Magnesia, Kainite,
Langbeinite, Epsom salts
OxidesSilicatesSulfides
Etc
Plant uptake as Mg2+ at root tip
Secondary clay and humus
Mg fertilizer
Soil Solution
Where you can goWhere you have been
More Info.
Soil Solution
Plant uptake as Mg2+ at root tip
Crop removal
Plant residue and Microbial population
Chelates in solution
Mg fertilizer
Dolomite, MgSO4, MgO, Mangesite,Magnesia, Kainite,
Langbeinite, Epsom salts
Where you can goWhere you have been
More Info.
Plant uptake as Mg2+ at root tip
Plant residue and Microbial population
Mineralization
Immobiliz
ation
Erosion
Chelates in solution
Soil Solution
Where you can goWhere you have been
More Info.
Plant residue and Microbial population
ErosionSoil Solution
Where you can goWhere you have been
More Info.
OxidesSilicatesSulfides
Etc
Plant uptake as Mg2+ at root tip
Plant residue and Microbial population
Leaching MgSO4
Chelates in solution
Secondary clay and humus
Soil Solution
Where you can goWhere you have been
More Info.
Parent materialnon-exchangeable 2% of all rock
Dolomite MagnesiteSerpentine BiotiteOlivine FosteritePyrope IoliteDiopside AugiteEnstatite ActinoliteHornblende TalcPhlogopite Clinochlore
OxidesSilicatesSulfides
Etc
Secondary clay and humus
Weathering
Soil Solution
Where you can goWhere you have been
More Info.
Secondary clay and humus
Weathering
PPT
Mg fertilizer
Soil Solution
OxidesSilicatesSulfides
Etc
Parent materialnon-exchangeable 2% of all rock
Dolomite MagnesiteSerpentine BiotiteOlivine FosteritePyrope IoliteDiopside AugiteEnstatite ActinoliteHornblende TalcPhlogopite Clinochlore
Dolomite, MgSO4, MgO, Mangesite,Magnesia, Kainite,
Langbeinite, Epsom salts
Where you can goWhere you have been
More Info.
Plant uptake as Mg2+ at root tip
Plant residue and Microbial population
Mineralization
Immobiliz
ation
Erosion
CEC
Leaching MgSO4
Chelates in solution
Secondary clay and humus
Weathering
PPTSoil Solution
Mg fertilizer
Mg 2+Parent materialnon-exchangeable 2% of all rock
Dolomite MagnesiteSerpentine BiotiteOlivine FosteritePyrope IoliteDiopside AugiteEnstatite ActinoliteHornblende TalcPhlogopite Clinochlore
OxidesSilicatesSulfides
Etc
Dolomite, MgSO4, MgO, Mangesite,Magnesia, Kainite,
Langbeinite, Epsom salts
Where you can goWhere you have been
More Info.
Deficiencies:pH 5.0 is best for Mg availability. A higheror lower pH depresses Mg uptake. High Kand Ca levels also interfere with uptake.
Where deficiencies occur:Highly leached humus acid soils or onsandy soils which have been limed heavily(due to Ca2+ competition). Deep sandysoils. Soils with high forage production (8-10ton/ac/yr) removal. Sometimes on soilshigh in K, Mg deficiencies are indicated bysoil test index values less than 100lbs/acre.
Toxicity Symptoms:none
Toxicities: Grass Tetany when K/(Ca+Mg)> 2.2
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Form taken up by plant: Mg2+
Mobility in Soil: yes/no
Mobility in Plant:yes as Mg2+ or Mg Citrate
Deficiency Symptoms: Interveinal chlorosis, necrosis, andGeneral withered appearance. Leaves arestiff and brittle and intercostal veins aretwisted. Observed in lower leaves first.Between veins striping, mottling, andblotching.
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Role of Mg in Plant Growth: Responsible for electron transfer inphotosynthesis. Central element ofchlorophyll molecule (6-25% of total plantMg). Required for starch degradation in thechloroplast. Involved in regulating cellularpH. Required for protein synthesis.Required to form RNA in the nucleus, Mgpectate in the middle lamella.
Role of Nutrient in Microbial Growth:Important for phosphorus metabolism.Helps to regulate colloidal condition of thecytoplasm.
Concentration in plants: 0.15% - 0.35% (1500-3500 ppm)
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Effect of pH on Availability: Highest Mg availability at pH 5.0.
Precipitated forms at low pH: MgCl2 , MgSO4 , Mg(NO3)2
Precipitated forms at high pH: MgO, MgCO3, Mg(OH)2, MgCa(CO3)2
Interactions with other nutrients: Uptake of K+, NH4
+, Ca 2+, Mn2+ by plantlimits Mg2+ uptake. H+ (low pH) can limitMg2+ uptake. Mg salts increasephosphorus adsorption.
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Fertilizer Sources:Dolomite (MgCa(CO3)2) (most common);Magnesium sulfate (MgSO4 x H2O)(Kieserite); Magnesium oxide (Mg(OH)2)(Brucite); Magnesite (MgCO3); Magnesia(MgO); Kainite (MgSO4 x KCl x 3H2O);Langbeinite (2MgSO4K2SO4); Epsom Salts(MgSO4 x 7H2O)
Location in Plants: In corn, 34% of total Mg is in grain.
Radioactive Isotopes: 23Mg t 1/2 = 11.6 sec27Mg t 1/2 = 9.6 min28Mg t 1/2 = 21.3 hr
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Enzymes that require Mg2+: Magnesium is a co-factor for manyenzymes. This includes enzymes involvedin glycolysis, carbohydrate transformationsrelated to glycolysis, Krebs cycle, themonophosphate shunt, lipid metabolism,nitrogen metabolism, “phosphate pool”reactions, photosynthesis, and othermiscellaneous reactions.
Examples:ATPase (phosphorylation),phosphokinases;RuBP carboxylase(photosynthesis); Fructose 1,6phosphatase (starch synthesis inchloroplasts); Glutamate synthase(ammonia assimilation in the chloroplasts);Glutathione synthase; PEP carboxylase
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Ionic Radius: 0.78 Angstroms
Hydration Energy: 1908 J mol-1
Toxicity Symptoms:none
Toxicities: Grass Tetany when K/(Ca+Mg)> 2.2
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References:
Ball, Jeffrey. 1994. Magnesium Cycle. As presented to SOIL 5813.
Brady, Nyle C. and Ray R. Weil. 1996. The Nature and Properties of Soils. 11th
Edition. Prentice Hall, Upper Saddle River, N.J.
Jacob, A. 1958. Magnesium - the fifth major plant nutrient. Staples Press Limited,London.
Johnson, G.V., W.R. Raun, and E.R. Allen. 1995. Oklahoma Soil FertilityHandbook. 3rd
ed. Okla. Plant Food Educational Society and Okla. State Univ. Dept. ofAgronomy, Stillwater, OK.
Johnson, G.V., W.R. Raun, Hailin Zhang, and Jeffrey A. Hattey. 1997.Oklahoma Soil
Fertility Handbook. 4th Edition. Oklahoma State University Department ofAgronomy, Oklahoma Agricultural Experiment Station, Oklahoma
CooperativeExtension Service, And Oklahoma State University Division of AgriculturalSciences and Natural Resources, Stillwater, OK.
Lauchli, A. and R.L. Bieleski (editors). 1983. Inorganic Plant Nutrition. Springer-Verlag,
Berlin.
Marschner, H. 1986. Mineral Nutrition of Higher Plants. 2nd ed. Academic Press,London.
Mengel, K. and E.A. Kirkby. 1978. Principles of Plant Nutrition. InternationalPotash
Institute, Bern.
West Virginia Univ. 1959. Magnesium and agriculture symposium. Morgantown,WV.
Authors: Jeffrey Ball, Mark Everett and Rick Kochenower, and Heather Qualls
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Form taken up by plant
Mobility in soil
Mobility in plant
Deficiency symptoms
Deficiencies
Where deficiencies occur
Toxicity symptoms/ToxicitiesRole of nutrient in microbial and plant growth
Concentration in plants
Effect of pH on availability
Precipitated forms at pH
Interactions with other nutrients
Fertilizer sources
Location in plants
Radioactive isotopesEnzymes that require Mg2+
Ionic radius/Hydration energy References Back to cycle
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Deficiencies:pH 5.0 is best for Mg availability. A higher or lowerpH depresses Mg uptake. High K and Ca levels also interfere with uptake.Where deficiencies occur:Highly leached humus acid soils or onsandy soils which have been limes heavily(due to Ca2+ competition). Deep sandysoils. Soils with high forageproduction (8 –10ton/ac/yr) removal.Sometimes on soils high in K, Mg deficiencies areindicated by soil test index values less than 100lbs/ac.