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Potassium
- 1. A group ofUdon 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 followingquestions 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 typesof 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 andGerman, 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 ofnutrients 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 wheredid 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 aground- breaking bulletin on potassium in IL soils almost a century ago. http://www.archive.org/stream/potassiumfromsoi00hopk#page/n3/mode/2up
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- 10. Unavailable (90 to98%) 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 potassiumin 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 marginsare associated with potassium deficiency
- 14. K deficiency symptomscan 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 ofK by grain crops is small compared to forages
- 16. Vegetable crops usea 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 applicationrates for fruit and vegetable crops in the US
- 18. Fertilizers do notactually contain K2O 1 lb of elemental K = 1.2047 lbs of K2O Crops do not actually take up K2O
- 19. The more highlyweathered 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 toextractable K in low CEC soils No maintenance Sufficiency
- 21. Crop response toextractable K in highCEC soils Crop response to extractable K in low CEC soils No maintenance Sufficiency
- 22. Iowa State hasupdated their K recommendations for corn and soybeans How do you convert between ppm and lbs/acre?
- 23. Variation in soiltest 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 differentstates 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 recommendmuch 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 methodsfor 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 Ksurvey 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 valuesfor K fluctuate during the year K is more available in wet soils
- 29. Drying of moistsamples increases soil test K
- 30. General rule ofthumb: 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 havehigh K fixation capacity
- 33. Economic response toK 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 happensto 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 SoilTest 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 temperatureand 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 nutrientuptake ! 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 Effectson Corn Yield with Increasing Soil Compaction Initial K Soil test = 102 ppm www.soils.wisc.edu/extension/teachingmaterials/Wolkowski/RowPlacedFertilizer2004.ppt
- 39. Plant analysis forK 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 documentedthat 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 levelsof magnesium and calcium generally need higher levels of potassium to maintain high crop yields due to competitive ion effects.
- 42. High soil testK: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 BalanceMatter? 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 salesin 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 inMOP 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 saltystuff !
- 48. White potash isproduced 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 fertilizerproduction and consumption Total world production = 33 million metric tons of K2O in 2007
- 50.
- 51. Canada has thelargest 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 theworld's largest fertilizer company #1 in potash, #3 in phosphate and #4 in nitrogen fertilizers
- 54. How much doespotash cost in IL this fall?
- 55. Potash prices wereup 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 Potashtrack differently than Ammonia and DAP?