I shared this presentation with my Soil Fertility class in October 2011.

1. A group of Udon Thani's Iron Ladies shout "No Potash!", a phrase
that has become their battle cry in a four year struggle against a
proposed mine in their village.

2. Answer the following questions based on information in 2 readings:
1) The New Thai Capitalism: Development or Disaster?
http://clpmag.org/article.php?article=The-New-Thai-Capitalism-Development-or-
Disaster_162
2) The potash project: Thailand's first underground mine – Canadian Mining
Journal (abridged version should be attached)
Questions:
1) Who are the “Iron Ladies” and what is their mission? Do you think the age and
gender of the “Iron Ladies” has affected the way Thai society, government
officials and industry reps have responded to their protests? What if the protests
were led by college students? or young male farmers?
2) Why did the mining company lobby for changes in Thailand's Mineral Act of
2002? What has the mining company done to address public skepticism about
foreign owned companies?
3) Identify several potential negative environmental impacts of the proposed
mining project.

3. 4) What types of technologies does the mining company plan to employ to minimize
negative environmental impacts?
5) What types of public benefits does the mining company claim will come about if the
mine is developed? Do any of the villagers believe these claims?
6) Estimate the potential economic value (in US dollars) of the Udon potash reserves.
Assume 500 million tons of potash ore with an average K2O content of 20% can be
economically extracted. Assume a world price of $500 per ton of potash fertilizer
containing 60% K2O.
7) How do the 2 articles differ in their tone? (Hint: compare words used to describe
local opposition to the mine)? Do you think one article is more likely to be accurate or
objective than the other? Explain.
8) How do you think members of your community would react if a mining company
wanted to extract minerals from deep underneath your community and claimed that
the mining would *not* significantly disrupt current land uses or harm the
environment?
9) As far as I can tell, mining still has not begun in Udon and the Iron Ladies have
remained unwavering in their opposition. What do you think will happen? Do you think
a compromise is possible?

4. In Latin and German, Kalium = Potassium ?
Why is potassium represented by the symbol K
39K is the dominant isotope.
40K (radioactive) and 41K (stable)
are used as tracers.

5. Typical quantities of nutrients in Midwest farm soils (kg/ha)
Element Total Exchangeable Solution
K 38,000 190 10-30
Ca 8000 2250 60-120
Mg 6000 450 10-20
N 3500 -na- 7-25
P 900 -na- 0.05-0.15
S 700 -na- 2-10
1 kg/ha = 0.89 lbs/ac
The total potassium content of most Midwest soils is
tens of thousands of lbs per acre-plow layer
but most of the K is locked up in minerals like
K feldspar that release K very slowly

6. Depth of
So where did all
loess cap
this potassium
come from?
K-rich
primary
minerals
A loess cap covers
about 2/3rds of IL
Glacial
outwash

7. Cyril Hopkins
wrote a ground-
breaking
bulletin on
potassium in
IL soils almost a
century ago.
http://www.archive.org/stream/potassiumfromsoi00hopk#page/n3/mode/2up

8. Is this possible?

9. Luxury consumption

10. Unavailable (90 to 98%)
K
K K+ K+
Soil Minerals Soil solution K+
(feldspar, mica)
K+
K K K Readily
available
(0.1 to 2%)
K+ K+ K+ K+
Soil Colloid Soil Colloid
Trapped K
K+ K+ K+ K+
Soil Colloid
Slowly available (1 to 10%)

11. Important potassium concepts
No significant gaseous forms
3rd most likely (after N and P) to be plant
limiting
Non-toxic at high concentrations
Does not promote eutrophication
(unlike N and P)

12. Role of potassium in plant nutrition
Remains in ionic form inside plants (rather than being
incorporated into organic molecules)
Very important osmotic regulator (lowers water
potential inside of plant cells)
Activator of over 80 enzymes
1-4% of plant dry matter (similar to N)
Important for tolerance of environmental and biotic
stresses (drought tolerance, winter hardiness,
resistance to fungal pathogens, resistance to insects)
Important for crop quality (flavor, color, stem strength)

13. Necrotic leaf margins are associated with
potassium deficiency

14. K deficiency symptoms can occur even when soil test K levels are high
Corn in ridge-till and no-till
systems are often first to
show K deficiency symptoms,
but they can occur in other
tillage systems as well.
Uptake of K by plants requires an active root system, especially in
the soil zone where plant-available K is located !!
When this soil zone is dry, uptake is limited. Anything that exerts additional stress
or limits root growth--compacted soil layers, root pruning, side-wall smearing--
further reduces K uptake, especially when root growth is restricted in the zones of
highest available K.

15. Crop removal of K by grain crops is small compared to forages

16. Vegetable crops use a lot of potassium !
Crop Yield N P2O5 K2O
Bell Peppers 180 cwt 137 52 217
Cabbage 20 tons 130 35 130
Peas 25 cwt 164 35 105
Potatoes (white) 30,000 lb 90 48 158
Snap Beans 4 tons 138 33 163
Sweet Corn 90 cwt 140 47 136
Tomatoes 20 tons 120 40 160
Many veggies use more K2O than N!

17. Average K2O application rates for fruit and vegetable crops in the US

18. Fertilizers do not actually contain K2O
1 lb of elemental K = 1.2047 lbs of K2O
Crops do not actually take up K2O

19. The more highly weathered
soils in southern IL tend to have
low CECs. Pockets of sandy
soils (grey shaded areas) in
northern and central IL also
have low CECs
Most soils in the “high” region
shown on this slide have CECs
12 centimols / kg.
1 centimol/kg = 1 meq / 100 g
Most soils in the “low” region
shown on this slide have CECs
< 12 centimols / kg.
The U of Ilinois recommends
higher soil test K for soils with
higher CEC!

20. Crop response to extractable K in low CEC soils
No maintenance
Sufficiency

21. Crop response to extractable K in highCEC soils
Crop response to extractable K in low CEC soils
No maintenance
Sufficiency

22. Iowa State has updated their K recommendations
for corn and soybeans
How do you convert between ppm and lbs/acre?

23. Variation in soil test K critical levels across the US and Canada
http://www.ipni.net/ipniweb/portal.nsf/0/c13f0cf310f1903e062577c7005a4bd7/$FILE/2010%20Critical%20P%20and%20K%20Maps.pdf

24. Why do different states have different soil test critical levels?
Part of the reason is differences in soils but climate, cropping
systems and data interpretation philosophy also matter.

25. Some labs recommend much higher K levels for soils with high CECs
http://www.spectrumanalytic.com/support/library/ff/Soil_test_P_and_K_buildup_and_drawdown.htm

26. Soil testing methods for potassium
used by US labs in 2005
Traditional method
Universal
extractant
adopted by more
NH4+ exchanges with labs every year
K+ on soil colloids

27. Soil Test K survey results
(> 4 million samples from ~ 60 labs)
Change between 2005 and 2010 % of samples below critical level
Declines in many states but not IL

28. Soil test values for K fluctuate during the year
K is more available in wet soils

29. Drying of moist samples increases soil test K

30. General rule of thumb:
4 lbs of K2O are required to raise soil test K by 1 lb

31. Annual application vs. build up and maintenance

32. Some soils have high K fixation capacity

33. Economic response to K fertilization is most likely when soil test K
is low and K fertilizer is cheap relative to the price of corn.
K fertilizer is cheap relative to grain prices
high
medium
K fertilizer is expensive low
relative to grain prices
low high

34. What really happens to
fertilizer K?
Only 20 to 60% of applied K is
taken up by crops in year 1
Highest recovery on low K soils
Why??
Slowly
Available K Unavailable K
Available K
The K in KCl (muriate of potash) is near 100% plant
available but is not the only source of K (and other
cations) in the soil. Also, crop roots normally explore a
much larger volume than the zone of amendment

35. Relationship Between Soil Test K Level and Yield
Response to Starter Fertilizer in WI - 1995
100
QRP
80 y=343-6.82x+0.034x2
if x<100
Yield response, bu/acre
60 y=0 if x>100
R2=0.52 n=54
40
20
0
-20
VL L O H EH
-40 (47) (19) (-2) (8) (1)
50 100 150 200 250
Soil test K, ppm
www.soils.wisc.edu/extension/teachingmaterials/Wolkowski/RowPlacedFertilizer2004.ppt

36. Relationship between temperature and maximum soil test K
level where yield response occurred to starter fertilizer
2500
Air temperature departure ,oF
1995 y = 1119 - 0.84x + 0.00017x2 1
2400 R2 = 0.97
Cumulative GDD
2300
0
2200
1994
-1
2100
1993 1996
2000
-2
100 110 120 130
Critical soil test K level, ppm
www.soils.wisc.edu/extension/teachingmaterials/Wolkowski/RowPlacedFertilizer2004.ppt

37. Compaction affects nutrient uptake !
Potassium Affected Most
• Compaction reduces porosity and
limits root growth
• Lowers soil O2 and slower
replenishment from the atmosphere
• O2 needed for root respiration and
active uptake of K
• Compacted soils are often
responsive to K fertilization
www.soils.wisc.edu/extension/teachingmaterials/Wolkowski/RowPlacedFertilizer2004.ppt

38. Row K Effects on Corn Yield with
Increasing Soil Compaction
Initial K Soil test = 102 ppm
www.soils.wisc.edu/extension/teachingmaterials/Wolkowski/RowPlacedFertilizer2004.ppt

39. Plant analysis for K in soybean leaves at R1 can be a useful tool for
identifying K deficiencies. Critical levels ranging from 1.2 to 1.7% K
have historically been recommended in many Corn Belt states.
It now appears that higher K levels are needed in
conservation tillage systems.
(Yin and Vyn, 2005)
Leaf samples consisted of the most recently fully
developed trifoliate leaves, including the petiole, collected
from 20 plants at R1 in mid- to late-July from each plot

40. It’s well documented that alfalfa will
take-up K beyond its needs if high
levels of soil or applied K are
available. This is referred to as “luxury
consumption”.

41. Soils containing high
levels of magnesium and
calcium generally need
higher levels of potassium
to maintain high crop
yields due to competitive
ion effects.

42. High soil test K:Mg ratios
Over many years of looking at plant analysis samples, we
have seen that where the soil test ratio (lb:lb) of K:Mg is
greater than 1.5:1; many crops are likely to suffer Mg
shortages. This is often in spite of the soil having
"adequate" amounts of Mg in the soil. Where the soil test
ratio of K:Mg is between 1:1 and 1.5:1, grass crops,
including corn may be at risk of an Mg shortage. While
such an induced Mg deficiency can reduce yields, it is
possibly a bigger problem for livestock that consume the
green chop or silage. When these high soil K:Mg ratios are
combined with low to marginally sufficient Mg and/or acid
soils, the probability of Mg deficiency increases.
http://www.spectrumanalytic.com/support/library/ff/Potassium_basics.htm

43. Does Cation Balance Matter?
http://www.pda.org.uk/leaflets/6/no6-print.htm
The relative concentration of potassium, calcium, magnesium,
ammonium, and other positively charged ions in the soil solution
influences their relative uptake.
Excessively high concentrations of one cation often results in
inadequate uptake of other cations.
For example, very high concentrations of calcium reduce uptake
Grass tetany
of potassium and very high concentrations of potassium reduce
magnesium uptake.
Cation balance affects animal health

44. Potassium Fertilizers
K 2O
Chemical
Material Content
Formula
%
“Potash” = muriate of potash = MOP
guaranteed
potassium chloride KCl 60 analysis
sul-po-mag K 2 SO 4 2MgSO 4 20
potassium nitrate KNO 3 44
potassium sulfate K 2 SO 4 50
Used in organic agriculture

45. Potassium fertilizer sales in IL
Material fall06 spring07
0-0-60 207,410 143,041
MOP 0-0-62 92,880 86,821
99.1 % of material grade 569,491 tons
94% of total

46. The chloride in MOP has
negative effects on some crops
Tobacco fertilized with MOP
produces cured leaves with muddy
and uneven color with excessive
hygroscopicity and poor burn.

47. MOP is salty stuff !

48. White potash is produced of KCl, NaCl and other salts. and
Potash ore is a mix by a process of dissolution
The KCl is concentrated using a flotation process which
recrystallization. Potash ore is dissolved under pressure in
skims off the surface of a fluid suspension of finely
hot brine, and MOP is precipitated further processed and
crushed ore. This concentrate is
as the brine cools and
pressure reduces. resulting fertilizer materialthis process, and
screened. The The iron is removed in is ~ 95 percent
the resulting MOP fertilizer isbecauseWhite MOP is generally
MOP. It is reddish in color white. iron impurities in the
at least are not removed in this process.
ore 98 percent potassium chloride.

49. Global K fertilizer production and consumption
Total world production = 33 million metric tons of K2O in 2007

50. http://minerals.usgs.gov/minerals/pubs/commodity/potash/mcs-2008-potas.pdf

51. Canada has the largest potash reserves
and also exports the most potash
Total global economic reserves ~ 8 billion metric tons

52. PotashCorp produces 23% of the world's supply of potash.
PC also controls most of the world's unused supply, and has
historically held back production to keep potash prices high.

53. PC is the world's largest fertilizer company
#1 in potash, #3 in phosphate and #4 in nitrogen fertilizers

54. How much does potash cost in IL this fall?

55. Potash prices were up about $5.50 a ton last week in
Illinois, with the average price at $639, ranging from
$600 to $710. Illinois prices remain about $25 a ton
cheaper than Iowa, which is more in line with our forecast
models, which puts spring prices at $690 a ton.

57. Why does Potash track differently than Ammonia and DAP?