Download - Science and management of Ca and Mg
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Calcium (Ca) has an atomic number of 20
and an atomic weight of 40.08
What does Ca share in common
with other elements in group IlA?
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Calcium (Ca) has an atomic number of 20
and an atomic weight of 40.08
Ca+2
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The plume from the burning reactor initially traveled in a northwest direction toward Sweden,
Finland and eastern Europe, exposing the public to levels up to 100 times the normal
background radiation. Contamination of grain and dairy products was a serious concern.
Both Sr-90 and I-131 migrate to vital organs in the body where they are impossible to
remove, serving as a constant source of unnecessary radiation and as a cause of cancer or
other diseases
Radioactive fall-out from Chernobyl
Sr can
substitute for
Ca with very
unhealthy
consequences
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element atomic number % by weight
oxygen 8 46.60
silicon 14 27.72
aluminum 13 8.13
iron 26 5.00
calcium 20 3.63
sodium 11 2.83
potassium 19 2.59
magnesium 12 2.09
titanium 22 0.44
hydrogen 1 0.14
phosphorus 15 0.12
manganese 25 0.10
fluorine 9 0.08
sulfur 16 0.05
chlorine 17 0.05
Calcium is the 5th most abundant element in the earth’s crust
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As a result, most young soils contain
large amounts of calcium
Old soils that are highly weathered and soils
that formed from parent materials low in Ca
tend to contain much less Ca.
Young Ca rich soil in IL Old Ca deficient soil in NC
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The highly weathered soils of Brazil’s
Cerrado region naturally had such low
Ca levels that cattle ranchers lost cattle
due to brittle Ca deficient bones and
large scale crop production was
considered impossible.
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The highly weathered soils of Brazil’s
Cerrado region naturally had such low
Ca levels that cattle ranchers lost cattle
due to brittle Ca deficient bones and
large scale crop production was
considered impossible.
> 150 million acres converted to ag since 1985,
Brazil is now the #1 soybean exporter
Enormous quantities of lime have been applied!!
Brazilian soybean breeders have also developed well
adapted soybeans varieties with high tolerance of Al toxicity
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Ca+2
Ca+2
Forms of calcium in soil
Ca-rich minerals
CaSO4 * 2H2O
CaAl2Si2O8
Calcium-organo-mineral complexes
Exchan
geable
Ca
+2
Most of the Ca in soil
So
lutio
n
Ca
+2
Plant
available
Ca
All of these forms of
Ca are linked but the
ones on the right side
of the slide are much
more dynamic
CaCO3
plagioclase
gypsum
calcium carbonate
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For most soils, Ca+2 is the dominant
exchangeable cation and cation in solution
exchangeable
cations
Ca+2
Ca+2
Ca+2
Ca+2 Ca+2
Ca+2
Ca+2
Ca+2
Ca+2
Ca+2
cations in solution
Ca+2
Ca+2
Ca+2
Ca+2
Ca+2 Ca+2
Ca+2
Ca+2
Solution concentrations of Ca in temperate region
soils tend to range from ~30 to ~300 ppm.
Solution concentrations are not the same as
extractable (soil test) concentrations.
15 ppm Ca
is adequate
for most
crops
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How many lbs of Ca arrive at the roots of a
corn crop that transpires 20” of water during a
growing season if the average soil solution
concentration is 15 ppm Ca?
1 acre-inch = 27,000 gallons
1 gallon = 8.3 lbs
27,000 gal/ac-in * 20 inches * 8.3 lbs/ gal = 4,482,000 lbs of H2O/ac
4,482,000 lbs * 15 / 1,000,000 = 67 lbs of Ca
Very few crops need more than 67 lb of Ca/ac
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Multi-valent
cations such
as Ca+2, Al+3
and Fe+3 are
important
binding
agents at this
scale.
Impact of cations on flocculation
of clay particles
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In contrast,
monovalent
cations such
as Na+ and
K+ cause
clay domains
to disperse.
Impact of cations on flocculation
of clay particles
What about Mg+2?
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Plant uptake of Ca commonly exceeds all other
elements except for N and K
Monocots generally contain less Ca (0.15-0.5% of dry plant tissue).
Dicots generally contain more Ca (1-3% of dry plant tissue)
Woody plants store large amounts of Ca
and often have similar uptake of Ca and N.
Ca movement within plants occurs mostly through the
transpirational stream (water moving upward through the
xylem) as opposed to in the phloem.
Ca movement to growing tissues that are not transpiring
(e.g.., fruits) is very restricted.
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Crop Yield N P205 K20 Ca Mg S
Lbs/acre
Corn (grain) 150 bu 110 53 40 2 8 10
Corn (stover) 4.5 tons 100 37 145 26 20 14
Wheat (grain) 40 bu 50 25 15 1 6 3
Wheat (straw) 1.5 tons 20 5 35 6 3 5
Soybeans (beans)
50 bu 188 41 74 19 10 23
Soybeans (stover)
6,100 lb 89 16 74 30 9 12
http://www.soil.ncsu.edu/publications/Soilfacts/AG-439-16/
Calcium content of grain and stover for corn, wheat and soybeans
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Location
N P2O5 K2O Ca Mg S
lb/ton
Alabama 52 12 50 19 4.5 3.3
N. Carolina 45 15 45 28 5.3 4.8
IPNI – N. Central 51 12 49 -na- 5.4 5.4
Alberta, Canada -na- 10-15 50-65 30 5-7 5-7
P. Northwest 50-70 8-16 48-72 28-35 5-8 4-6
http://www.aces.edu/pubs/docs/A/ANR-0449/
http://www.soil.ncsu.edu/publications/Soilfacts/ag-439-16W.pdf
http://nanc.ipni.net/articles/NANC0005-EN
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex10073
http://grant-adams.wsu.edu/agriculture/forage/pubs/PNW0611NutrientManagementGuideforDrylandandIrrigated%20AlfalfaintheInlandNorthwest.pdf
Variation in nutrient levels in alfalfa
So how much Ca is removed by a typical alfalfa crop?
100 to > 300 lbs/ac
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Physiological importance of Ca
Cell division and elongation
Cell wall development
Cell membrane function
Cell protection against toxins
Nitrate uptake and metabolism
Activity of key enzymes
Starch metabolism
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Many fruits and vegetables have dramatic Ca deficiency symptoms such as
Black Heart in celery and broccoli, Tipburn in lettuce and cabbage, White Heart
or Hollow Heart in cucurbits, Blossom End Rot in tomatoes and peppers, and
Pops in peanuts. Tree fruit with low calcium exhibit storage problems such as
bitter-pit in apples, cork-spot in apples and pears, cracking in cherries, and other
degradation of the fruit while in storage.
Ca deficiency is usually associated with growing points (aka meristems)
For example: buds, unfolding leaves, fruits and root tips
Lack of moisture or non-uniform moisture availability is frequently
associated with symptoms of calcium deficiency
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Most commercial fruit producers in
the Pacific NW spray their apple and
pear trees with CaCl2 or Ca(NO3)2.
Some varieties receive 3-4
treatments, others 6-7. The
application of foliar Ca is cost
effective and can dramatically
improve fruit quality.
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High Response Crops
The following crops have been found to be especially
sensitive to Ca availability:
apples, broccoli, brussel sprouts, cabbage, carrots,
cauliflower, celery, cherries, citrus, conifers, cotton,
curcurbits, melons, grapes, legumes, lettuce, peaches,
peanuts, pears, peppers, potatoes, tobacco, and tomatoes
http://www.spectrumanalytic.com/support/library/ff/Ca_Basics.htm
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According to the U of I, Ca deficiency does not occur in Illinois when soil pH is greater
than 5.5.
“Calcium deficiency associated with acidic soils should be corrected using limestone. The laboratory procedure used for Ca is easy and reliable—probably
more accurate than the K test— but since the deficiency does not exist, there is no reason to
recommend the test”.
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According to Tiedjens,
pH measurements do not give a true
picture of the need for Ca additions
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Low Ca and Mg levels in plant tissue were not always associated
with low pH levels. High Ca and Mg levels in plant tissue were not
always associated with higher pH levels. Other factors which may
have influenced plant tissue levels of Ca and Mg include competitive
cations, crop disease/injury and sub-soil pH.
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Soil pH was clearly not the only factor
impacting plant uptake of Ca and Mg
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Interactions with other nutrients
Competitive cations: The relative amounts of other cations such as
Na+, K+, Mg+2, NH4+, Fe+2, and Al+3 impact plant uptake of Ca+2. Additions
of large amounts of Ca+2 displace other cations from exchange sites
which may temporarily increase their availability to crops but also
increase their tendency to leach. High K applications have been known
to reduce the Ca uptake in apples, which have inefficient Ca uptake and
translocation within the tree.
Phosphorus: Free or un-combined Ca is normally present in alkaline
soils. This Ca is available to interact with other nutrients. Free Ca reacts
with P to form insoluble (or very slowly soluble) Ca-P compounds that
are not readily available to plants.
Boron: High soil or plant tissue levels of Ca can inhibit B uptake and
utilization. Calcium sprays and soil applications have been effectively
used to help detoxify B over-applications.
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SOIL TEXTURE CALCIUM MAGNESIUM
Sandy 400 60-75
Silt loam 800 150-200
Levels of soil test Ca and Mg (lbs/A)
considered adequate for crop production Illinois Agronomy Handbook
A state wide (598 fields in 52 IL counties)
soil fertility survey conducted in 2007/2008
reported average Ca and Mg levels of
4,452 and 732 lbs/ac, respectively.
4500 >> 800 !!
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Portion of nutrients taken up by corn that are typically supplied by 3 main mechanisms
Nutrient Root
interception Mass flow Diffusion
% of uptake
Nitrogen <1 80 19
Phosphorous 2 5 93
Potassium 2 18 80
Calcium 150 375 0
Magnesium 33 600 0
Sulfur 5 300 0
Why are some of these #s greater than 100%???
The amount of Ca and Mg brought to roots by the transpirational
stream is often much greater than crop uptake
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Why isn’t Ca uptake higher, when more is available?
In contrast with most other nutrients, Ca is taken up
almost exclusively by young root tips.
K uptake is generally higher than Ca uptake even though
solution concentrations of Ca are often 10 times greater
than K concentrations.
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Impact of clay mineralogy on Ca availability
Ca Saturation, %
High CEC clays generally need > 70% Ca saturation to provide adequate Ca availability
Low CEC clays generally only need 40-50% Ca saturation
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Review of factors affecting Ca nutrition
Total Ca supply
Soil pH
CEC
% Ca saturation
Relative abundance of other cations
Clay mineralogy
Moisture availability and uniformity of uptake
New root growth
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Many crop consultants promote Ca products!
Most claims do not appear to be supported by
research but Ca supplementation programs
merit consideration, especially when growing
“high response” crops
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http://www.turfformula.com/images/images-new/super-cal.jpg
A wide range of calcium
products are available on the market.
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Tissue testing can help identify situations when
Ca supplementation is likely to be of value.
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Liming Material Approx. % Ca
Calcitic Limestone 32
Dolomitic Limestone 22
Hydrated Limestone 46
Precipitated Lime 60
Blast Furnace Slag 29
Ca fertilizers Approx. % Ca.
Gypsum 22
CaCI2 36
Ca(NO3) 2 19
Ca-Chelates 3-5
Calcium amendments
When evaluating Ca
products, carefully
consider price,
application method
and whether a liming
material is
appropriate.
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Does gypsum improve soil structure ??
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Ca+2 is a stronger flocculator than Mg+2
but Mg+2 is not a weak flocculator
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Ca saturated Mg saturated
Which of these soils is Ca saturated?
Thin sections showing different degrees of surface crust formation
Are these soils representative of real field soils?
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Ca saturated Mg saturated
Thin sections showing different degrees of surface crust formation
Some crust prone soils are likely to benefit from additional Ca+2 but care should be
taken to avoid creating K or Mg deficiencies through excessive Ca saturation.
Definitely not !
Ca+2 is a stronger flocculator than Mg+2 but other cations like
Fe+3 and Al+3 are even stronger!
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Recent article in Journal of Soil and Water Conservation (peer reviewed scientific journal)
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(Norton, 2009)
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(Norton, 2009)
+
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Large additions of Ca can cause
large losses of other cations
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Jack Maloney, IN farmer
Keith Schlapkohl, IA Farmer
Routine applications of gypsum are used by some successful farmer innovators
in the Midwest region.
Mike Starkey, IN Farmer
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STOCKTON, IA — Keith Schlapkohl concedes he doesn't know everything about farming. That hasn't stopped him from trying new things on his Scott County farm. "It seems for every one question I get answered, 10 more are raised," he says. Schlapkohl has been trying different ideas dealing with improving nitrogen efficiency and using gypsum on his Eastern Iowa fields. During this time, his yields have averaged close to 300 bushels per acre for corn and 60 bushels for soybeans.
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Excerpt from the Iowa Farmer Today article: “Schlapkohl believes gypsum increases production by improving water infiltration. "Its chemical tillage," says Schlapkohl about gypsum. By using gypsum, he has been able to lower the magnesium levels in his soils. Higher magnesium levels tighten up the soil, he explains. Using gypsum also has increased the amount of oxygen in the soil and increased N efficiency, Schlapkohl notes. (he has harvested >300 bu of corn/acre with less than 100 lbs of fertilizer N) He uses a calcium-sulfate product from Cedar Rapids that has a higher ratio — 3:1 — of calcium to sulfur, compared with other sources that have a 1:1 ratio. Schlapkohl says there is more available calcium and less heavy metals in this product compared with regular gypsum. This substance is not as powdery as typical gypsum. He has a business that spreads the gypsum product over the winter. Because he also farms, Schlapkohl likes to spread the product between harvest and planting and stay close to home.”
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Mike Starkey says his background in accounting helped him to
prioritize information gathering functions at the farm, including a
heavy use of on-farm trials to evaluate the impact of various
inputs.
“We are not afraid to change things when we find something that
works better,” Mike Starkey says.
The Starkey family has been a no-till operation since 2000 after
trying it briefly in the early '90s. Once he and his family learned
how to properly set up no-till planting equipment, place nitrogen
efficiently and monitor calcium and magnesium levels in soils, the
operation was successful in using no-till.
Starkey echoes Maloney’s comments about water infiltration
improvements after using Gypsoil. “It is amazing how water does
not stand anymore. When it rains hard, water is just gone now.”
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Figure 1. Varying degrees of clay dispersion in soils. The higher amounts of dispersal (4 and 5) indicate a soil's suitability for gypsum application. No.0 displays slaking (breaking off of soil particles), compared to 1 to 5 which show clay dispersion
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What about the jar test?
A tablespoon of any soluble salt (including table
salt) will flocculate clay in a quart jar!
Without the addition of a flocculating agent, it is normal for fine clay to
stay in suspension after soil is shaken vigorously with water.
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Excellent review of research on the value
of gypsum in humid regions
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Soils which respond positively to gypsum have greater ability
to adsorb both Ca+2 and SO4-2 than soils which are not
responsive. This could be developed into a routine soil test.
Green data points
represent soils that
responded positively to
gypsum
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Magnesium (Mg) has an atomic number of 12
and an atomic weight of 24.3
What does Mg share in common
with other elements in group IlA?
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Magnesium (Mg) has an atomic number of 12
and an atomic weight of 24.3
Mg+2
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According to the U of I, Mg deficiency occasionally occurs in IL for both corn and
soybean but is limited to sandy, low organic matter soils.
Southern Illinois University research has shown no response to applied Mg even when the Mg test from the surface soil
was below recommended levels. They observed that Mg levels below the surface 7-inch level were adequate and apparently met the needs for optimum crop production
even when surface levels were considered deficient.
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Magnesium deficient corn
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Magnesium deficient tomato leaves
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Physiological role of Mg in plants
Central element of the chlorophyll molecule
Enzyme activator and a constituent of many enzymes
Sugar synthesis
Starch translocation
Plant oil and fat formation
Nutrient uptake control
Increase Fe utilization
Aids N fixation in legume nodules
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The basic structure of a chlorophyll molecule is a porphyrin
ring, coordinated to a central atom. This is very similar in
structure to the heme group found in hemoglobin, except that
in heme the central atom is iron, whereas in chlorophyll it is
magnesium.
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High Response Crops
The following crops have been found to be especially sensitive
to availability of Mg:
alfalfa, blueberry, beet, broccoli, cabbage, cauliflower,
celery, clover, conifers, cotton, cucumber, eggplant, lettuce,
onion, pepper, potatoes, pumpkin, spinach, squash,
tobacco, tomato and watermelon
http://www.spectrumanalytic.com/support/library/ff/Mg_Basics.htm
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Spectrum Analytic Inc (a plant and soil testing lab in OH) analyzed
thousands of plant tissue samples in 2010. The results indicate that
many crops would benefit from more magnesium. In looking at the
data, keep in mind that this is a biased survey. Plant samples are
more often than not submitted to find out why a crop is
underperforming.
http://www.spectrumanalytic.com/doc/_media/library/newsletter/spectrum_ag_winter_2010.pdf
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Sources of Mg
Dolomitic limestone is a mixture of CaCO3 and MgCO3 and is the
lowest cost source of Mg but should only be applied when lime is
needed. The Mg content of dolomitic limestone varies from 8-10%.
To be most effective as a source of Mg, dolimitic lime should be
broadcast and incorporated.
Neutral salt sources of Mg
Sul-po-mag has a Mg content of 11%. The sulfur (S) and K2O
concentrations are ~22%.
Epsom salts = MgSO4·7H2O = 9.9% Mg
MgCl2, Mg(NO3)2 and Mg chelates can be used as solutions and
foliar sprays
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Cation Balancing??
Proposed by Firman Bear, William Albrecht and
others prior to the advent of soil test calibration
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Claims associated w/ “balanced” Ca:Mg ratios
• Improves soil structure
• Reduces weed populations
• Stimulates populations of earthworms and beneficial microorganisms
• Improves forage quality
• Excess soil Mg “ties up” and promotes leaching of other plant nutrients
• Better “balance” of soil nutrients
• Improved plant and animal health
• “Cows milk easier”
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U of WI Conclusions
• Alfalfa yield related to exchangeable K and soil pH, not Ca:Mg ratio
• Neither Ca or Mg additions affected weeds
• Earthworms related to organic matter, not Ca:Mg ratio
• Alfalfa quality related to pH and stand, not Ca:Mg ratio
• No justification to use calcitic over dolomitic lime or adding extra Ca
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NCR 103 Committee NC Regional Publication 533 Soil Cation Ratios for Crop Production
– Ca and Mg levels can be balanced but too low
– Field research does not support “optimal” Ca:Mg ratio concept
Concludes:
“A sufficient supply of nutrient cations is the most important consideration in making economic fertilizer recommendations”
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Bear, F.E., and S.J. Toth. 1948. Influence of calcium on availability of other soil cations. Soil
Sci. 65:67-74.
Eckert, D.J., and E.O. McLean. 1981. Basic cation saturation ratios as a basis for fertilizing and
liming agronomic crops: 1. Growth chamber studies. Agron. J. 73:795-799.
Eckert, D.J. 1987. Soil test interpretations: Basic cation saturation ratios and sufficiency levels.
In J.R. Brown (ed.) Soil Testing: Sampling, Correlation, Calibration, and Interpretation. Special
Publication No. 21. Soil Science Society of America. Madison, WI.
Graham, E.R. 1959. An explanation of theory and methods of soil testing. Missouri Agric. Ext.
Stn. Bull. 734.
Hunter, A.S. 1949. Yield and composition of alfalfa as affected by various calcium -magnesium
ratios in the soil. Soil Sci. 67:53-62.
Liebhardt, W.C. 1981. The basic cation saturation concept and lime and potassium
recommendations on Delaware’s Coastal Plain soils. Soil Sci. Soc. Am. J. 45:544-549.
McLean, E.O., R.C. Hartwig, D.J. Eckert, and G.B. Triplett. 1983. Basic cation saturation ratios
as a basis for fertilizing and liming agronomic crops. II. Field studies. Agron. J. 75:635-639.
Simson, C.R., R.B. Corey, and M.E. Sumner. 1979. Effect of varying Ca:Mg ratios on yield and
composition of corn and alfalfa. Commun. Soil Sci. and Plant Anal. 10:153-162.
Many studies have evaluated the base saturation ratio concept -
none have concluded that specific optimum ratios exist
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Why no crop response to “Ca:Mg ratio” ?
• Ca and Mg levels in the soil solution are normally high compared to plant uptake
• Plant K uptake is 2-4 times that of Ca and Mg despite much lower levels of K in the soil solution
• Roots preferentially take up K and exclude Ca and Mg.
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K:Mg ratio may be more important than Ca:Mg ratio
A number of studies (e.g., Rahmatullah and Baker (1981)
and Stout and Baker (1981) have reported an inverse
relationship between K:Mg ratio and Mg uptake by corn
seedlings
Wilkinson et al. (1987) reported that applications of high
rates of K to cool season grass pastures, whether from
manure or inorganic fertilizers, increased the incidence of
grass tetany.
.
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Johannsonn and Hahlin (1977) reported a strong
inverse relationship between K:Mg ratio and Mg
uptake by oats, and only a minor effect of Ca
saturation on K and Mg uptake.
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1. When the soil test K to soil test Mg ratio exceeds 1.5 many crops will have
trouble taking up Mg, almost regardless of the soil Mg test level.
2. When the ratio is between 1 and 1.5 some grasses will have occasional Mg
problems, and corn is the most sensitive grass species.
3. When the ratio is less than 1, there are few Mg problems in any crop,
assuming that the soil Mg is not initially deficient.
4. When the soil pH is less than 6.0, situations described in points 1 through 3
will occur at a lower soil K:Mg ratio and the Mg shortage will be more severe.
5. It is rare to find an example where the soil levels of K or Mg have any effect on
Ca uptake.
6. It is very rare to find poor Ca uptake when the soil Ca saturation is higher than
50%. Some exceptions to this can be found with some crops, such as apples,
that use Ca inefficiently.
http://www.spectrumanalytic.com/support/library/ff/Is_Magnesium_a_Hidden_Problem_in_your_area.htm
From the Spectrum Analytic, Inc website:
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Good overview of
Mg concepts
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