I developed these slides for the Soil Fertility class that I teach at Western Illinois University.

1. How
important is
CALCIUM?

2. Answers to reading Qs should be
submitted using the IA before the
start of class TODAY (11/4)

3. What is FGD gypsum, how does it differ from mined gypsum and why has
agricultural use of FGD gypsum increased in recent years?
Ron Chamberlains company Gypsoil is one of the biggest if not the biggest
marketer of FGD gypsum to farmers. Spend a little time browsing the
Gypsoil website www.gypsoil.com and discuss some interesting info you
found.
Mike Starkey and Jack Maloney are continuous no-tillers who use cover
crops and lots of other innovative practices in addition to gypsum. If you
could ask either of them 1 question related specifically to their experience
with gypsum, what would you ask?
The title of the article is Gypsum may enhance soil-growing conditions
rather than Gypsum enhances soil growing conditions. How convinced are
you of the value of gypsum after reading the article? Do you think the article
should have contained any additional information (e.g., more explanation of
how gypsum impacts soil structure or nutrient availability). Discuss your
perspective.
Questions

5. MSIS presentations (2011-2014)
provide a window into the science and
practice of agricultural utilization of
gypsum and are all available on-line.

6. This Ohio State U publication
presents current science based-
information about agricultural
utilization of gypsum.

7. 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?

8. Calcium (Ca) has an atomic number of 20
and an atomic weight of 40.08
Ca+2

9. Have you ever heard of the Chernobyl Disaster?
A fire and explosion at the Chernobyl Power Plant released large quantities of radioactive particles
into the atmosphere on April 26, 1986. A 30 km exclusion zone was established.

10. 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 radiation and as a potential cause of cancer.
Radioactive fall-out from Chernobyl
Sr can
substitute for
Ca with very
unhealthy
consequences

11. 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
http://www.daviddarling.info/encyclopedia/E/elterr.html

12. Most young soils
contain large
amounts of
calcium.
Old, highly
weathered soils
contain much less
calcium.
Young Ca rich soil in IL Old Ca deficient soil in NC
Soils formed from parent materials low in Ca
(e.g., quartz sand) contain low levels of Ca

13. 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.

14. 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
Large quantities of lime have been applied!!
Brazilian soybean breeders have also developed well
adapted soybeans varieties with high tolerance of Al toxicity

15. Ca+2
Ca+2
Forms of calcium in soil
Ca-rich minerals
CaSO4 * 2H2O
CaAl2Si2O8
Calcium-organo-mineral complexes
ExchangeableCa+2
Most of the Ca in soil
Solution
Ca+2
Plant
available
Ca
All of these forms of
Ca are part of
biogeochemical
cycles but the ones
on the right side of
the slide are most
dynamic
CaCO3
plagioclase
gypsum
calcium carbonate
2.0–2.5 g/l
0.015 g/l
Very insoluble

16. 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
Soil water Ca concentrations in temperate region
soils tend to range from ~30 to ~300 ppm.
15 ppm Ca is
considered
adequate for
most crops
Ca+2

17. 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 concentration
in soil water 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 ppm = 67 lbs of Ca
Very few crops need more than 67 lb of Ca/ac

18. 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

19. 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
?

20. ag.arizona.edu/pubs/crops/az1414.ppt
Does this
difference
matter?

21. Recent research indicates that high Mg levels
can destabilize the structure of some soils

22. Plant uptake of Ca sometimes 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.

23. 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

24. 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

25. 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

26. 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

27. 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.

28. High Response Crops
The following crops have been reported 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

29. 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”.

30. 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 !!

31. According to Tiedjens,
pH measurements do not give a true
picture of the need for Ca additions

32. In this study, low Ca and Mg levels in plant tissue were not always
associated with low pH levels and high Ca and Mg levels in plant
tissue were not always associated with higher pH levels. Other
factors which influence plant tissue levels of Ca and Mg include
competitive cations, crop disease/injury and sub-soil pH.

33. 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
Phosphorus 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 mass flow aka the
transpirational stream is often much greater than crop uptake

34. 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.

35. 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
. Large
additions 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 interacts 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.

36. Impact of clay mineralogy on Ca availability
Ca Saturation, %
High CEC
clay
Low
CEC
clay
High CEC clays generally need > 70% Ca saturation to provide adequate Ca availability
Low CEC clays generally only need 40-50% Ca saturation
Calciumavailability
High Mg may
be an issue.

37. 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

38. Many crop consultants promote Ca products!
Many claims do not appear to be supported
by research but Ca supplementation
programs merit consideration, especially
when growing “high response” crops

39. http://www.turfformula.com/images/images-new/super-cal.jpg
A wide range
of calcium
products are
available on
the market.

40. http://www.algreatlakes.com/PDF/factsheets/ALGLFS35_Plant_Tissue_Testing_Sufficiency_Levels_of_Row_Crops.pdf
Tissue testing can help identify situations when
Ca supplementation is likely to be of value.

41. 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 a) PRICE
b) APPLICATION
METHOD and
c) WHETHER A
LIMING MATERIAL
IS APPROPRIATE.

42. 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?

43. Magnesium (Mg) has an atomic number of 12
and an atomic weight of 24.3
Mg+2

44. 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.

45. Magnesium deficient corn

46. Magnesium deficient tomato leaves

47. ?

48. Are you on sandy soils?
Looks like a Mg deficiency
to me… some Epsom salts
through the drip should
clear it up.
I would do both run 1# ES per
acre foliar to jump start and
apply 5# per acre in drip as
needed. Don't go too high
because you can flush your
nitrate out of the plants.
http://talk.newagtalk.com/forums/thread-view.asp?tid=588924

49. 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

50. 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.

51. 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

53. High K concentration in soil solution interferes with Mg uptake by ryegrass

54. For the turf manager, one of Mg’s most important
functions is its involvement in the transport of soluble
carbohydrates from leaves to sites of utilization in
roots, rhizomes and growing points.
One common observation associated with Mg
deficiency is a sharp decline in the root: shoot ratio
(weight of roots/weight of shoots). When magnesium is
inadequate, the root: shoot ratio will often decline to
less than half that of a magnesium sufficient plant.
This means that when turf grasses are experiencing
inadequate magnesium, they will produce less root
mass and roots do not grow as deeply.

55. 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.
732 > 200 !!

56. 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

57. 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

58. Good overview of
Mg concepts
http://www.ipni.net/ppiweb/bcrops.nsf/$webindex/9657B817A2FFCA5E85257723004A0967/$file/BC22010-Page-26-28.pdf

59. Cation Balancing??
Proposed by Firman Bear, William Albrecht and
others prior to the determination of critical levels

60. 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”

61. 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

62. 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”
Sufficient supply is an especially important concern in low CEC soils

63. 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 –
I am not aware of any that concluded specific cation ratios are optimal across diverse soils

64. Why no crop response to “Ca:Mg ratio” ?
• Ca and Mg levels in the soil solution are normally high
compared to plant uptake
• Plant uptake of K 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
• Soils studied may not have been sensitive to high Mg

65. 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.
.

66. Does gypsum improve soil structure ??
It has long been known that gypsum can be used to
remediate soils that have poor structure due to high Na levels

67. Recent article in
Journal of Soil and
Water
Conservation
(peer reviewed
scientific journal)
Does
science
support
the use of
gypsum
in the
Midwest?

68. (Norton, 2009)
Soils receiving gypsum had less run-off and
less loss of sediment and soluble P

69. Using Gypsum to Affect Soil Erosion Processes
and Water Quality.
Dale Norton
A driving force in soil erosion is the low electrolyte content
of rain water. Various electrolyte sources have proven useful
in serving as electrolyte sources such as phosphogypsum,
lime and various salts, however, each has other potential
problems. We performed a number of studies on low cost
gypsum from scrubbing air from coal fired power plants for
pollution control (FGD gypsum) and found the neutral salt
produced is an excellent electrolyte source which is slowly
soluble in rainwater and has few if any potential environmental
problems. It has proven very useful in keeping soil clays
flocculated and maintaining greater infiltration rates,
therefore, reducing runoff and erosion.
https://scisoc.confex.com/crops/2009am/webprogram/Paper52042.html

70. Water that is too clean causes corrosion in metal
pipes

71. This research presents
evidence that it is beneficial
to manage soils for high
Ca:Mg ratios *IF* they are
prone to sealing.

72. Jack Maloney,
IN farmerKeith Schlapkohl,
IA Farmer
Routine applications of gypsum are used by some
successful farmer innovators
in the Midwest region.
Mike Starkey,
IN Farmer

73. 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.

74. 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/a 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.”

76. 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.”

77. Once a Pollutant, ` Scrubber Sludge ' Finds a Market
By John J. Fialka
The Wall Street Journal, Page B1, 10/05/1998
Some electric utilities are spinning gold out of the gunk they once spewed in the air.
To comply with the 1970 Clean Air Act, power companies have been "scrubbing" the
smoke coming out of their stacks to remove sulfur and fly ash, then dumping the
wastes into landfills. Now, they are finding farmers and construction companies will
buy the stuff.
Near Oak Ridge, Tenn., a unit of Caraustar Industries Inc. is building a factory to
make wallboard out of sulfur residue produced at the mammoth Tennessee Valley
Authority power plant next door. About 180 miles east, near Clarksville, Babb
Cellular Concrete Co. is building a plant to make a special lightweight concrete out
of fly ash from another TVA plant.
Farmers, too, are buying sulfur residue -- called " scrubber sludge " -- because it
improves soil and increases their crop yields. Ken A. Curtis. who farms and runs a
fertilizer business in Prairie City, Ill., sells between 20,000 tons and 30,000 tons
a year at $6 a ton. "Wherever you put that stuff," he says, "it just greens up.

79. 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

80. 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.

81. 24 hrs after salt was added to flask on the right
High electrolyte concentration promoted flocculation of clay
Class
Demo
11/4

82. Excellent review of research on the value
of gypsum in humid regions

83. 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