U.S. Department of the Interior

U.S. Geological Survey

Open File Report 2016–1167

Potash—A Vital Agricultural Nutrient Sourced 

from Geologic Deposits

U.S. Department of the Interior

U.S. Geological Survey
Cover. Photos of underground mining operations, Carlsbad, New Mexico, Intrepid Potash Company, Carlsbad West Mine. 
Potash—A Vital Agricultural Nutrient 

Sourced from Geologic Deposits

By Douglas B. Yager

Open File Report 2016–1167

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2016

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Suggested citation:

Yager, D.B., 2016, Potash—A vital agricultural nutrient sourced from geologic deposits: U.S. Geological Survey OpenFile Report 2016–1167, 28 p., https://doi.org/10.3133/ofr20161167.

ISSN 0196-1497 (print)

ISSN 2331-1258 (online)

ISBN 978-1-4113-4101-2
iii

Acknowledgments

The author wishes to thank Joseph Havasi of Compass Minerals for a surface tour of their 

Great Salt Lake operations. Eric Rogers, Intrepid Potash Company, provided a surface tour of the 

Wendover, Utah, site. Gregory Bruce and Ralph Ramstetter of Intrepid Potash Company provided 

an underground tour of the Carlsbad West Mine in Carlsbad, New Mexico. Background discussions with Dr. Raymond H. Johnson of Navarro Research and Engineering, Inc., were very helpful. Peer reviews by Stephen Jasinski, Mary Ellen Benson, and Rhonda Driscoll, all of the U.S. 

Geological Survey, improved this report. The author thanks Sally Almeria of the U.S. Geological 

Survey for her technical edit. This report was made possible by support from the U.S. Geological 

Survey Central Mineral and Environmental Resources Science Center’s Industrial Mineral Project 

led by Anna Wilson.

Contents

Acknowledgments........................................................................................................................................iii

Introduction.....................................................................................................................................................1

What is Potash? ....................................................................................................................................1

Potash as an Essential Nutrient .........................................................................................................4

Early History of Potash.........................................................................................................................4

Geologic Setting and Geographic Distribution of Potash .......................................................................4

Quaternary, Nonmarine Potash Sources..........................................................................................4

Great Salt Lake, Utah ..................................................................................................................6

Bonneville Salt Flats, Wendover, Utah .....................................................................................6

Searles Lake in California...........................................................................................................6

Paleozoic Marine-Type Potash Deposits..........................................................................................7

Delaware Basin, Southeast New Mexico ...............................................................................7

Paradox Basin, Southeast Utah ................................................................................................7

Holbrook Basin, East-Central Arizona....................................................................................11

Michigan Basin ..........................................................................................................................12

Williston Basin, North Dakota .................................................................................................14

Nontraditional Potential Geologic Sources of Potassium for Fertilizer.....................................15

Mining Methods for Potash........................................................................................................................15

Underground Mining Methods .........................................................................................................15

Potash Recovery from Lacustrine and Groundwater Brines Through Solar Evaporation .....18

Conversion of Underground Mining to In Situ Solution Mining ..................................................18

Primary In Situ Leach Solution Mining............................................................................................18

Past and Current Potash Production........................................................................................................21

Import-Export Supply Chain—Current and Projected Use...................................................................21

Summary........................................................................................................................................................26

References....................................................................................................................................................26
iv

Figures

1. Index map of features discussed in the text............................................................................2

2. Paleogeographic reconstruction showing the Early Permian seaway where potash

was deposited in the Delaware Basin, New Mexico .............................................................8

3. Paleogeographic reconstruction showing the Middle Pennsylvanian seaway

where potash was deposited in the Paradox Basin, Utah.....................................................9

4. Photographs of a drill core from 1 Cane Creek, west of Moab, Utah ................................10

5. Paleogeographic reconstruction showing the Early Permian seaway where potash

was deposited in the Holbrook Basin, Arizona......................................................................11

6. Conceptual model of marine-type evaporite deposition in a restricted seaway.............12

7. Paleogeographic reconstruction showing the late Silurian seaway where potash

was deposited in the Michigan Basin.....................................................................................13

8. Paleogeographic reconstruction showing the Middle Devonian seaway where

potash was deposited in the Williston Basin, North Dakota...............................................14

9. Photographs of Intrepid Potash Company surface operations, Carlsbad, 

New Mexico ................................................................................................................................16

10. Photographs of Intrepid Potash Company, Carlsbad West Mine underground 

potash deposits and mining methods......................................................................................17

11. Photographs of Compass Minerals, sulfate of potash surface evaporation and 

brine transfer operations, Great Salt Lake, Utah...................................................................19

12. Photographs of Intrepid Potash Company, groundwater brine transfer and 

surface evaporation operations, Wendover, Utah................................................................20

13. Photograph of Intrepid Potash Company, solar evaporation ponds at the in situ 

solution mine west of Moab, Utah ...........................................................................................21

14. Graph showing U.S. potash production between 1915 and 2012 .......................................22

15. Graph showing a comparison of U.S. and world potash production between 

1918 and 2011...............................................................................................................................22

16. Graph showing global potash production in 2012 and 2013 ................................................23

17. Graph showing global potash reserves..................................................................................23

18. Graph showing U.S. potash imports between 1900 and 2012..............................................24

19. Graph showing the ratio of domestic to world potash production between 

1919 and 2011...............................................................................................................................25

20. Graph showing the price of muriate of potash between 1960 and 2014 ...........................25
v

Conversion Factors

International System of Units to Inch/Pound

Multiply By To obtain

Length

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi)

Area

square kilometer (km2

) 247.1 acre

square kilometer (km2

) 0.3861 square mile (mi2)

Volume

cubic kilometer (km3

) 0.2399 cubic mile (mi3)

Mass

metric ton per day 1.102 ton per day (ton/d)

metric ton per year 1.102 ton per year (ton/y)

Tables

1. Common, naturally occurring potash salts...............................................................................3

2. Selected rock-forming silicate minerals containing abundant potassium.........................3

3. Potash occurrence in the United States...................................................................................5

Potash—A Vital Agricultural Nutrient Sourced from 

Geologic Deposits

By Douglas B. Yager

Abstract

This report summarizes the primary sources of potash in 

the United States. Potash is an essential nutrient that, along 

with phosphorus and nitrogen, is used as fertilizer for growing crops. Plants require sufficient potash to activate enzymes, 

which in turn catalyze chemical reactions important for water 

uptake and photosynthesis. When potassium is available in 

quantities necessary for healthy plant growth, disease resistance and physical quality are improved and crop yield and 

shelf life are increased. Potash is a water-soluble compound 

of potassium formed by geologic and hydrologic processes. 

The principal potash sources discussed are the large, stratiform 

deposits that formed during retreat and evaporation of intracontinental seas. The Paradox, Delaware, Holbrook, Michigan, and Williston sedimentary basins in the United States 

are examples where extensive potash beds were deposited. 

Ancient marine-type potash deposits that are close to the 

surface can be mined using conventional underground mining 

methods. In situ solution mining can be used where beds are 

too deep, making underground mining cost-prohibitive, or 

where underground mines are converted to in situ solution 

mines. Quaternary brine is another source of potash that is 

recovered by solar evaporation in manmade ponds. Groundwater from Pleistocene Lake Bonneville (Wendover, Utah) and 

the present-day Great Salt Lake in Utah are sources of potashbearing brine. Brine from these sources pumped to solar 

ponds is evaporated and potash concentrated for harvesting, 

processing, and refinement. Although there is sufficient potash 

to meet near-term demand, the large marine-type deposits are 

either geographically restricted to a few areas or are too deep 

to easily mine. Other regions lack sources of potash brine from 

groundwater or surface water. Thus, some areas of the world 

rely heavily on potash imports. Political, economic, and global 

population pressures may limit the ability of some countries 

from securing potash resources in the future. In this context, 

a historical perspective on U.S. potash production in a global 

framework is discussed.

Introduction

This summary report discusses the U.S. geologic sources, 

mining, and recovery methods of the industrial mineral potash. 

It was prepared as part of the U.S. Geological Survey’s Industrial Minerals Project. While the information presented here 

can be found in literature elsewhere, the purpose of this report 

is to summarize and compile information on potash resources 

in the United States. The import-export supply chain of potash 

consumption for the United States is also discussed in a global 

context. Geographic and geologic features mentioned in the 

text are shown in figure 1.

What is Potash?

Potash is a water-soluble compound of potassium formed 

by geologic and hydrologic processes. Along with phosphorus 

and nitrogen, potash is an essential nutrient necessary to sustain plant life. In addition to being used as fertilizer, potash has 

been used for textile bleaching, glass manufacturing, and soap

production. The world’s major potash resources are related to 

evaporite deposits that principally occur as potash salts such as 

sylvite, which is potassium chloride in natural mineral form, 

and sylvinite, which consists of potassium chloride and halite 

(table 1). Halite is also known as sodium chloride or common 

salt. Sylvite and sylvinite are generally found with chlorides, 

sulfates, and halite in evaporite sequences (Orris and others, 2014). Industrial phrases to describe potash varieties are 

muriate of potash (MOP) and sulfate of potash (SOP). MOP is 

potassium chloride, whereas SOP is potassium sulfate. 

Potassium, the nutrient-bearing element in potash, is an 

alkali metal contributing approximately 3.2 percent by weight 

as potassium oxide in the Earth’s crust. Potassium is estimated 

to be the seventh most abundant element on Earth (Fountain 

and Christensen, 1989; Rudnick and Gao, 2003). Potassium 

is a cation that readily bonds with available anions to produce chemical compounds. It is rarely found in its elemental 

form in nature because it usually is chemically bound to other 

elements. Although potassium is a major element in silicate 

minerals including feldspars, micas, nepheline, leucite, and 

in whole rocks (table 2), silicate minerals are not currently a 

major source for potash for agriculture. 
GSL WSIMLB

MR

MC

HB

Color shaded relief image from 

National Elevation Dataset (20

by John J. Kosovich, USGS, D

GOM WM

B

LL

Z

UB

SRS

UPPB M

MUD SJDHM Colorado Plateau

F H

DU

C DB GM

DV

LM

AR

SM

SL CH

AM

DM

CBP

WB

BD

BH SU

Great

 Basin

WA

Wyoming

Colorado

New Mexico

Arizona

Nevada

California

Utah

Idaho

SB SH
Introduction 3

Figure 1 (previous page). Index map of features discussed in the text. (Towns, squares: D, Durango, Colo.; C, Carlsbad, N.Mex.; H, 

Holbrook, Ariz.; F, Flagstaff, Ariz.; DV, Death Valley, Calif.; B, Bishop, Calif.; SB, Santa Barbara, Calif.; HE, Hersey, Mich.; W, Wendover, 

Utah; Z, Zenda, Idaho; and M, Moab, Utah. Large, western U.S. Pleistocene lakes, blue (labeled) filled areas: LL, Lake Lahontan; and 

LB, Lake Bonneville. Large, modern remnant of Lake Bonneville, light blue: GSL, Great Salt Lake. Small lakes, circles: CH, China Lake, 

Calif. (ancient, dry); and SL, Searles Lake, Calif. Black dotted lines, ancient potash evaporite basins: WB, Williston Basin; MB, Michigan 

Basin; DB, Delaware Basin; HB, Holbrook Basin; and PB, Paradox Basin. Dotted line, other sedimentary basin: UB, Uinta Basin. Uplifts 

and arches: BD, Bowdoin dome; MC, Miles City arch; BH, Black Hills uplift; SU, Sioux uplift; WA, Wisconsin arch; KA, Kankakee arch; 

FA, Findley arch; AA, Algonquin arch; CA, Cincinnati arch; DU, Defiance uplift; MU, Monument upwarp; UP, Uncompahgre Plateau; SJD, 

San Juan dome; and SRS, San Rafael Swell. Other structural features: CBP, Central basin platform; MR, Mogollon Rim; HM, Hogback 

monocline. Mountain ranges, triangles: AM, Apache; DM, Delaware; GM, Guadalupe; LM, Lava; SH, Spangler Hills; SM, Slate; AR, 

Argus; GOM, Goshute; SIM, Silver Island; and WM, Wasatch. Brown dashed line, border of the Great Basin; brown solid line, border of 

the Colorado Plateau)

Table 1. Common, naturally occurring potash salts. (Modified from Garrett, 1996)

Compound/mineral Formula

Potassium

oxide

(percentage)

Potassium oxide K2

O 100.00

Sylvite KCl 100.00

Sylvinite KCl+NaCl 63.17

Langbeinite K2

SO4•2MgSO4 22.70

Carnallite KCl•MgCl2 6•H2

O 16.95

Kainite KCl•MgSO4

•3H2O 18.92

Leonite K2SO4

 MgSO4 4H2O 25.69

Hanksite Na22K(SO4

)

9

(CO3)2Cl 3.00

Polyhalite K2

SO4•MgSO4•2CaSO4•2H2O 15.62

Table 2. Selected rock-forming silicate minerals containing abundant potassium. (Modified from Barker 

and others, 2008)

[wt. %, weight percentage; ND, not detected; NA, not applicable]

Mineral Family Formula Potassium (K)

(wt. %)

Potassium

oxide (K2O)

(wt. %)

Potassium feldspar Feldspar KAlSi3

O8 14.0 16.9

Leucite Feldspathoid KAlSi2

O6 17.9 21.6

Nepheline Feldspathoid Na3

KAl4Si4O16 13.0 15.7

Kalsilite Feldspathoid KAlSiO4 24.7 29.8

Muscovite Mica KAl2

(AlSi3O10)(F,OH)2 9.0 10.9

Biotite Mica K(Mg,Fe)3

AlSi3O10(OH)2 7.6 9.2

Phlogopite Mica KMg3

AlSi3O10(F,OH)2 9.4 11.3
4 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

Potash as an Essential Nutrient

Potash is an essential nutrient for food crops. It is 

obtained primarily from geologic environments. Feeding an 

ever-growing human population requires a constant supply of 

potash and other essential soil nutrients. The primary constituents in agricultural fertilizers are nitrogen (N), phosphorus (P), and potassium (K). Fertilizers are sold with numeric 

N-P-K labels. A 10-10-10 label, for example, indicates that 

the fertilizer product contains 10 percent nitrogen, 10 percent 

phosphorus, and 10 percent potassium in the form of potash. 

The optimal proportion of nitrogen-phosphorus-potassium in 

a fertilizer varies between plant species because of differences 

in the efficiency of plant uptake (Baligar and others, 2001).

High crop yields and vital plant health depend on sufficient potash (Armstrong, 1998; Wang and others, 2013). Plants 

utilize potassium in many growth processes; principal among 

these is enzyme activity. The number of enzymes activated 

in plants depends on the quantity of available potassium and 

the rate at which potassium enters a plant cell. Enzymes, once 

activated, catalyze chemical reactions that regulate multiple 

plant functions. One such function, photosynthesis, which is 

essential for both sugar and starch production, is controlled by 

an enzyme requiring sufficient potassium. Another function 

dependent upon the potassium-enzyme interaction is a plant’s 

ability to transport water to its entire system by means of the 

opening and closing of stomata (Armstrong, 1998). Stomata 

are the micropores of plant leaves and stems that open when 

water is available and close during dry periods to prevent 

water loss. Efficient stomata function also helps to ward off 

microbial attack because microbes often enter a plant through 

stomata pores (Melotto and others, 2006). Soils enriched with 

potassium improve plant quality and reduce plant diseases. 

When potassium is available in quantities necessary for 

healthy plant growth, disease resistance and physical quality 

are improved and crop yield and shelf life are increased. 

Early History of Potash

The term potash was first used to describe the evaporated 

residue from wood chips that had been leached in a pot of 

water. The evaporated residue contained “pot ashes” that were 

a source of potassium and used as a fertilizer for plants. The 

first U.S. patent granted to Samuel Hopkins in 1790 involved a 

new apparatus and process for making pot ash (Paynter, 1990). 

In the early 1900s, the United States obtained most large 

quantities of potash fertilizer from Germany (Turrentine and 

Shoaff, 1919). Due to a potash shortage and dependence on 

foreign potash imports during the early 1900s, the U.S. Congress authorized the U.S. Department of Agriculture (USDA) 

to research U.S. potash sources (Turrentine and Shoaff, 1919). 

USDA’s authority was expanded by Congress in 1916 to 

include evaluation of commercial potash production methods. Recovery of potash from kelp was explored near Santa 

Barbara, California, and an experimental plant that was constructed in 1917 was capable of processing 90.72 metric tons 

of raw kelp per day (Turrentine and Shoaff, 1919). However, 

the early methods of potash extraction from wood chips and 

kelp were inadequate to meet fertilizer demand, and mining 

of large geologic sources of potash soon became the principal 

focus of the U.S. potash industry.

Geologic Setting and Geographic 

Distribution of Potash

Potash that is highly soluble and readily bioavailable to 

plants is derived from potash salts that were precipitated from 

ancient seas or are concentrated in modern surface water or 

groundwater brines. The term bioavailable in this paper is 

defined as the ability of a molecule to be absorbed by a plant 

for use in its healthy growth. 

The largest mined U.S. potash deposits are marine in 

origin and located in areas that were inundated by Paleozoic 

intracontinental seas. These inland seas were calcium rich and 

generally sulfate poor (Warren, 2010). Less extensive U.S. 

sources of potash are associated with Quaternary continental 

interior lacustrine brines (Spencer and others, 1985). Interior 

lacustrine brines were formed in areas lacking basin outlets 

and freshwater recharge where brine would become concentrated during evaporation. Tertiary basin-wide, marine-type 

potash deposits are uncommon in the geologic record. 

The following sections review the geologic setting and 

geographic distribution of various U.S. potash deposits. Most 

current and past potash production in the United States has 

been concentrated in the West and Southwest. Other mapped, 

but largely unmined, potash reserves are located in the Northeast and north-central United States (table 3).

Quaternary, Nonmarine Potash Sources

Brines that formed in intracratonic, nonmarine, closed 

basins with no or minimal outflow are economically important 

sources of potash in the United States (Orris, 2011). Brine is 

defined as saltwater that has a high concentration of sodium 

and chloride but can also contain calcium, magnesium, sulfate, 

potassium, iron, lithium, and bromine along with multiple 

other trace constituents (Domagalski and Eugster, 1990; 

Tripp, 2009). This report does not attempt to further subdivide 

these Quaternary U.S. brine sources by age. There was an 

attempt, however, to identify Quaternary brine sources that are 

extracted from groundwater reservoirs that possibly evolved 

from Pleistocene lakes (such as Lake Bonneville near Wendover, Utah, and Searles Lake in California) and from modernday surface water (such as the Great Salt Lake in Utah). 

Quaternary brines have formed in the Great Basin section of the Basin and Range Province, encompassing an area 

of the western United States that includes northern Nevada and 

eastern California (Garrett, 1996). The Basin and Range is a vast 

expanse of broad depressions, or basins, with adjacent mountain 

ranges. The mountains vary in age, lithology, and composition. 
Table 3. Potash occurrence in the United States modified from Warren (2010). Dashed line separates Quaternary brine from Paleozoic, ancient mari[SOP, sulfate of potash; NA, not applicable; MOP, muriate of potash]

Location Age Brine source Source Mine method Potash minerals Producing Referenc

Great Salt Lake, Utah Quaternary Nonmarine Lake brine Solar evaporation SOP Yes Bingham (1

Garrett (1

Sevier Lake, Utah Quaternary Nonmarine Groundwater brine NA SOP No Garrett (199

Bonneville Salt Flats, 

Wendover, Utah

Quaternary Nonmarine Brine recovered from 

wells

Solar evaporation MOP Yes Garrett (199

Clayton Valley, Nevada Quaternary Nonmarine Groundwater brine NA Sylvinite No Garrett (199

Searles Lake, California Quaternary Nonmarine Groundwater brine Solar evaporation MOP No Smith (2009Delaware Basin,

Carlsbad, New Mexico

Upper Permian; 

Lower Triassic

Marine McNutt zone of the 

Delaware Basin

Conventional underground mining Sylvite, carnallite, langbeinite Yes Lowenstein 

Delaware Basin,

Carlsbad, New Mexico

Upper Permian; 

Lower Triassic

Marine McNutt zone of the 

Delaware Basin

Conventional underground mining Langbeinite Yes Lowenstein 

Delaware Basin,

Carlsbad, New Mexico

Upper Permian; 

Lower Triassic

Marine McNutt zone of the 

Delaware Basin

In situ, solution leach, 

solar evaporation

MOP Yes Bureau of L

Managem(2015)

Paradox Basin, Moab,

Utah

Middle

Pennsylvanian

Marine In situ leach, solution 

mining of Paradox Formation

In situ, solution leach Sylvite in halitesylvite cycles Yes Hite (1961)

Williams

(1994)

Holbrook Basin,

Holbrook, Arizona

Permian Marine Supai Group (Possible underground 

and solution leach)

Sylvite, carnallite, 

polyhalite

No Rauzi (2000

Michigan Basin,

Michigan

Lower to Upper 

Silurian

Marine Salina A-1 evaporite In situ, solution Sylvinite, carnallite No Matthews a

Egleson (

Williston Basin, North 

Dakota and Montana

Devonian Marine Prairie Formation NA Sylvite, carnallite No Anderson a

Swinehar(1979)
6 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

Neogene extension and associated thinning of the continental 

lithosphere in the western United States caused many areas 

of the Great Basin to become topographically low. A series of 

lowland basins surrounded by relatively high mountain ranges 

developed over a broad region during crustal extension. The 

topographically low areas evolved into closed basins that lacked 

a hydrologic outlet. Badwater Basin in Death Valley National 

Park, with an elevation of 86 meters (m) below sea level, is an 

example of extreme subsidence within the Great Basin (Craig 

and others, 2012). 

Closed-basin brines have formed in topographic depressions filled by lakes in several areas of the Great Basin. 

Surface water has evolved to brine compositions in continental interior lakes where brine concentrations are not diluted 

by precipitation and inflow from surface water or upwelling 

from groundwater. Groundwater brine has also formed in 

areas formerly occupied by closed-basin brine lakes. Potash 

is extracted from closed-basin brine primarily through solar 

evaporation of lake water or groundwater that is pumped from 

wells that intersect porous evaporite layers (Garrett, 1996). 

Great Salt Lake, Utah

Utah’s Great Salt Lake formed in the northeast part of the 

Great Basin along the western flank of the Wasatch Range. The 

Great Salt Lake is what remains of the much larger, freshwater 

Lake Bonneville that occupied the area from about 32,000 to 

10,000 years B.P (Oviatt, 1987). Lake Bonneville sedimentary 

deposits contain evidence of freshwater species, including trout 

and ostracod fossils (Oviatt, 1987). A catastrophic outflow event 

about 15,000 years ago lowered the former Lake Bonneville water 

level by 114 m. The lake overtopped its rim at Red Rocks pass 

near Zenda, Idaho, and released an estimated 4,700 cubic kilometers of lake water down the Snake River (Jarrett and Malde, 1987). 

The Great Salt Lake began evolving toward a brine composition 

15,000 years ago. The Wasatch Range borders the Great Salt Lake 

to the east and is geologically complex. The range comprises 

Precambrian schist, quartzite, and quartz monzonite, overlain by 

Paleozoic carbonates, Mesozoic sandstone, limestone and shale 

units, and Tertiary felsic volcanic rocks (Davis, 1983). 

Potash is geochemically conservative in Great Salt Lake 

brine and becomes more concentrated with increasing chloride 

concentration (Spencer and others, 1985). Being geochemically 

conservative means that the potash tends to stay in solution 

until it is highly concentrated and eventually precipitated during evaporation. Potash that is sufficiently concentrated in lake 

brine can be harvested by solar evaporation. Differences in the 

chemical concentration of potassium in brine determines where 

harvesting by solar evaporation is advantageous. Changes in 

Great Salt Lake salinity have been caused, in part, by a railroad 

embankment that was constructed in 1959 that divides the lake 

into two segments. Potassium concentrations in brine are highest in the northern arm of the lake. In contrast, the southern arm 

of Great Salt Lake can have potassium concentrations that are 

one-half of a percentage point less concentrated compared to 

the northern arm (Spencer and others, 1985). 

Bonneville Salt Flats, Wendover, Utah

Groundwater beneath the Bonneville Salt Flats, a remnant 

of former Lake Bonneville, is the second oldest mined potash 

resource in the United States; Searles Lake in California is the 

oldest. Potash was initially produced from groundwater brine 

at Wendover, Utah, in 1917. Today, solar evaporation at the 

surface of potassium-rich groundwater pumped from beneath 

the Bonneville Salt Flats yields about 90,700 metric tons per 

year of MOP (Garrett, 1996; Intrepid Potash, 2013). 

The Bonneville Salt Flats are bordered on the west 

by Middle Cambrian to Lower Triassic marine limestone, 

dolomite, and shale. Other rock units bordering the western 

edge of the Salt Flats include Jurassic to Miocene intrusive 

rocks, Tertiary sedimentary rocks, and Miocene rhyolite. 

Rhyolite is restricted to the Goshute Mountains of the Toano 

Range. To the north, the Salt Flats are bounded by the Silver 

Island Mountains of the Pilot Range, which are dominated 

by a 6,096-m-thick section of Paleozoic limestone, dolomite, 

quartzite, and siltstone. Granitic intrusive and tuffaceous rocks 

border the area to the north (Anderson, 1957; Schaeffer, 1960). 

As with similar brine deposits of the Great Basin, the 

Bonneville Salt Flats lack an external drainage so water that has 

collected in the basin since the Pleistocene has evolved compositionally toward brine. The brine of the Salt Flats is similar to that 

of the Salar de Atacama, a closed basin, intracontinental brine 

located in the Atacama Desert of Chile. Brines of the Bonneville Salt Flats and Salar de Atacama are saturated with sylvinite 

(Garrett, 1996). Brine wells of the Bonneville Salt Flats range 

in depth from just a few meters to 366 m at the top of what is 

inferred to be volcanic bedrocks (Turk and others, 1973).

Searles Lake in California

Searles Lake is a Holocene remnant of the larger Pleistocene Lake Lahontan that formed along the eastern margin of 

the Great Basin. It is bordered to the east by the Slate Mountains, which consist of schist, gneiss, and slate; to the south by 

the porphyritic andesite of the Lava Mountains; to the west by 

the Argus Mountains, which consist of Paleozoic limestone; 

and to the southwest by the Spangler Hills, which consist of 

quartz monzonite intrusive rocks crosscut by diorite dikes 

(Smith, 2009). Searles Lake formed about 150,000 years ago 

when China Lake, located to the west, overflowed and filled 

the Searles Lake depression. During the Pleistocene, Searles 

Lake was about 172 m deep (Giambastiani and Bullard, 2010). 

The present-day desert climate of this region, located near 

the southern margin of Death Valley, California, has very low 

precipitation and high evaporation rates.

The first U.S. potash production occurred at Searles Lake 

in 1916 and continued episodically until 1996 (Garrett, 1996). 

Three evaporite layers containing a varied combination of 

water-soluble salts are present under Searles Lake. The more 

complex salt mixtures are nearer the surface. The variety of salts 

deposited at Searles Lake may be attributed, in part, to discharge 

from thermal springs near Bishop, California (Garrett, 1996). 
Geologic Setting and Geographic Distribution of Potash 7

Of the three evaporite layers, the bottommost layer is 

a simple mixture of sodium carbonate and halite (Smith and 

Haines, 1964). The upper and lower salt layers described in 

Smith and Haines (1964) contain mixtures of multiple soluble 

salts, including the potash mineral hanksite. Hanksite is 

most abundant in the upper layer. Brines containing sylvite, 

borax, sodium sulfate, halite, and water have historically been 

pumped from the highly porous upper and lower layers and 

processed in a series of evaporators that concentrate MOP and 

SOP (Garrett, 1996).

Paleozoic Marine-Type Potash Deposits

The principal potash sources are from the extensive, 

bedded deposits that formed during retreat and evaporation 

of intracontinental seas. Episodes of seaway transgression 

and regression occurred at multiple intervals throughout the 

Paleozoic. The Delaware, Holbrook, Michigan, and Williston 

sedimentary basins are examples where extensive potash beds 

were deposited. Paleogeographic reconstructions are used in 

this report to show those areas affected by seaway encroachment and potash deposition.

Delaware Basin, Southeast New Mexico

The Permian Delaware Basin in New Mexico is host to 

extensive potash deposits. The Delaware Basin deposits were 

the principal source of U.S. potash beginning in 1931. These 

deposits continue to be mined today. When New Mexico potash production was near its peak in 1966 and before the giant 

potash deposits of Canada were discovered, the Delaware 

Basin was the source of about 25 percent of the world’s potash 

(Jones and Madsen, 1968). In 2006, the Delaware Basin 

deposits supplied 19 percent of the potash for domestic use 

(Barker and others, 2008).

The Delaware Basin formed in what today is west Texas 

and southeast New Mexico. The basin is bordered on the east 

by the Central basin platform and on the west by the Guadalupe Mountains. Midland Basin, east of the Central basin 

platform, is not known for potash deposits. The Delaware 

and Apache Mountains border the basin on the southwest and 

south, respectively. The basin has a 9,144-m-thick accumulation of Cambrian to Quaternary sedimentary rocks. Potash 

formed in the 609-m-thick Salado Formation that is part of 

the Ochoa Series (Lowenstein, 1988). The Ochoa Series is 

a sequence of ocean-basin carbonate reef, shoal, shale, and 

turbidite sandstone deposits. The series formed when a Permian seaway advanced into the area of what is today southern 

Arizona and New Mexico; northern Sonora, Mexico; and 

west-central Texas (fig. 2) (Hayes, 1964). 

Salt evaporites that contain potash form stratiform 

beds that overlie the basin, reef, and shoal marine-carbonate 

deposits. The McNutt zone of the Salado Formation contains 

multiple potash beds that are interbedded primarily with halite 

and polyhalite but also contains minor siltstone and anhydrite 

(Lowenstein, 1988).

Paradox Basin, Southeast Utah

The Paradox Basin is a northwest-trending structural 

foreland basin formed during the Paleozoic because of 

downwarping and infilling by clastic sedimentary deposits, 

evaporite salts, and limestone. Basin deposits are composed of more than 6,096 m of Cambrian to Quaternary 

sedimentary rocks. Sedimentary units consist of 4,572 m 

of terrigenous clastic sediments shed along the Uncompahgre uplift to the east during the Pennsylvanian to Permian Period. A 1,219- to 1,829-m section of Pennsylvanian 

evaporites formed in the Paradox Basin during retreat of an 

intercontinental seaway that had inundated most of what is 

Utah (fig. 3). 

The Paradox Basin is located mostly in southeast 

Utah and southwest Colorado, but it extends into northeast 

Arizona and northwest New Mexico. A carbonate platform 

in the south bordering the central Paradox Basin forms a 

constructional deposit of carbonaceous minerals with topographic relief and is a remnant of a Paleozoic seaway. The 

evaporite salts that were deposited in the Middle Pennsylvanian are used to define the basin boundary. The basin is 

bordered on the northeast by a Precambrian-cored anticlinal 

uplift associated with the Uncompahgre Plateau (Nuccio 

and Condon, 2000). The San Juan dome, a Precambriancored uplift partly covered by Tertiary volcanic rocks, forms 

the eastern boundary of the basin. Cretaceous sedimentary 

rocks exposed along the Hogback monocline southwest of 

Durango, Colorado form the southeast border. The southern 

and southwest basin borders are not well defined structurally but are delineated mainly by the extent of Pennsylvanian 

evaporite deposits and by the Monument upwarp, a classic 

Colorado Plateau monoclinal fold (Nuccio and Condon, 

2000). The San Rafael Swell, a Laramide dome that formed 

over uplifted Precambrian rocks, marks the northwest basin 

boundary. The Uinta Basin merges with the Paradox Basin 

along the northern margin of the Paradox Basin. 

The Pennsylvanian Paradox Member of the Hermosa 

Formation is an economic source of potash currently mined 

near Moab, Utah. Potash deposition in the Paradox Basin 

was controlled over time by evolution of brine compositions with late-stage brines having a higher concentration of 

potassium. Potash in brine is highly soluble, and potassium 

minerals are among the last phases to precipitate. Common 

precipitation sequences for ocean brine are calcite-gypsum 

or anhydrite-halite-potash. Episodic transgressive (inundation) and regressive (retreat) seaway events are recorded 

in a section of core collected near the active Cane Creek 

Mine, 14.5 kilometers (km) west of Moab, Utah. A 283-m 

section of continuous core shows four black shale and 

two limestone depositional intervals preceded by evaporite mineralization. Some shale intervals are hydrocarbon 

rich and have been investigated as source rocks for oil and 

gas in the Paradox Basin (Nuccio and Condon, 2000). The 

Cane Creek core can be viewed online at https://my.usgs.

gov/crcwc/core/report/16647, or researchers may view the 
8 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

Delaware 

Basin

Figure 2. Paleogeographic reconstruction of western North America for the Early 

Permian (Modified from Blakey, 2011). Location of present day Delaware Basin in New 

Mexico, and state boundaries shown for reference. Areas in light blue were inundated 

by the Permian seaway. (Copyright by Ron Blakey, Colorado Plateau Geosystems, used 

with permission.)
Geologic Setting and Geographic Distribution of Potash 9

Figure 3. Paleogeographic reconstruction of western North America for the Middle 

Pennsylvanian (Modified from Blakey, 2011). Location of present day Moab, Utah, 

along the northern Paradox Basin margin, and state boundaries shown for reference. 

Areas in light blue were inundated by the Pennsylvanian seaway. (Copyright by Ron 

Blakey, Colorado Plateau Geosystems, used with permission.)

Moab Paradox

Basin
10 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

Figure 4. Cane Creek Well Number 1; USGS Core Research Center ID: F016. A, Interval 589.18 to 593.14 meters; banded, 

centimeter-scale gray to millimeter-scale black anhydrite overlying light brown to gray halite. B, Interval 802.54 to 806.35 

meters; banded light- to dark-gray halite overlying dark-gray anhydrite. C, Interval 825.40 to 829.36 meters; potash layers 

are reddish-hued and are intergrown with light-gray to light-brown halite. White sections are Styrofoam that represents 

sections of missing core. 

A

B

C

physical core by contacting personnel at the U.S. Geological 

Survey core library at http://geology.cr.usgs.gov/crc/index.

html. Researchers have documented 28 separate evaporite 

mineralization events in the Paradox Basin during the Middle 

Pennsylvanian period, with 18 of the intervals containing 

potash (Garrett, 1996). Evaporite intervals of the Cane Creek 

Well Number 1 drill core contain mainly halite or intergrown 

halite-sylvite. These minerals indicate episodes of seawater 

influx that diluted the brine such that it was no longer saturated with potash.

Evaporite minerals present in the Cane Creek core 

suggest that the brine evolved from a high sulfate and halite 

system (anhydrite-halite) into a low sulfate, concentrated 

potassium, sodium, chloride system (halite-sylvite). Figure 

4A–C shows three core intervals that represent brine evolution 

and potash deposition. 
Geologic Setting and Geographic Distribution of Potash 11

Holbrook Basin, East-Central Arizona

Exploration drill-hole data collected in the mid-1960s 

from the Pennsylvania- Permian-aged Holbrook Basin, located 

in eastern Arizona, identified a significant potash resource. The 

Holbrook Basin is a northwest-southeast oriented structural 

basin located east of Flagstaff, Arizona. This basin is bordered to the south by the Mogollon Rim and to the north and 

northeast by the Defiance uplift. The basin consists of about 

1,829 m of sedimentary rocks that thin outward from Holbrook, Arizona. Rocks in the central part of the basin consist 

of a 305- to 457-m-thick section of Triassic clastic sedimentary rocks (Blakey, 1979, 1990). These Triassic rocks contain 

red beds of the Moenkopi Formation that are composed of a 

shale-dominated sequence of interbedded mudstone, siltstone, 

and sandstone. These rocks overlie the porous cross-bedded 

sandstone of the Coconino Sandstone. The Lower Permian 

Schnebly Hill Formation that underlies the Triassic red beds 

and sandstone is host to the evaporite deposits. The basal 

Schnebly Hill consists of sands, silts, and muds that transition 

to a thick section of bedded evaporites in the upper part of the 

formation. The evaporites formed during retreat of an Early 

Permian seaway (fig. 5). Devonian to Lower Pennsylvanian 

strata uncomformably overlie the Precambrian-floored basin 

(Rauzi, 2000). 

Potash was deposited as a single layer overlying a halite 

layer in the Schnebly Hill Formation described in Blakey 

(1979, 1990). Potash thicknesses range from 1.5 to 9 m and 

extend across an area of 1,554 square kilometers (km2

) (Rauzi, 

2000). Some of the thickest potash zones occur beneath the 

Figure 5. Paleogeographic reconstruction of western North America for the Early Permian 

(Modified from Blakey, 2011). Holbrook Basin evaporites formed during encroachment of an 

inland sea into east central Arizona during Late Pennsylvanian to Early Permian. (Copyright 

by Ron Blakey, Colorado Plateau Geosystems, used with permission.)

Holbrook

Basin
12 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

current boundaries of the Petrified Forest National Park and 

an adjacent area proposed for park expansion. Potash depths 

range from 213 to 610 m and are accessible by either conventional underground or in situ solution mining. Recoverable 

potash resource estimates vary, but assuming a uniform 20 

percent potassium oxide content, the Holbrook Basin potash 

resource ranges from 210 million to 1.75 billion metric tons 

(Rauzi, 2000, 2008). 

Michigan Basin

The Michigan Basin contains extensive potash deposits 

consisting of bedded sylvinite. Both shallow- and deep-precipitation models have been proposed for potash formation in the 

Michigan Basin. Gill (1977) suggested that potash precipitated 

in the central part of the Michigan Basin during an episode 

of inland sea transgression and subsequent evaporite deposition in a salt flats environment. An alternative, deep-water 

model for potash deposition was proposed by Schmalz (1969). 

His model suggests an environment where seawater became 

stratified in dissolved oxygen with high concentrations at 

the surface and low concentrations at depth. The oxygenated 

conditions at the surface helped initiate crystallization with 

the most soluble phases precipitating last and at the top of the 

stratigraphic sequence. Deposition of potash in the deepest 

water indicates evaporation of potash near the former seaway 

surface, density separation, and accumulation at a depth where 

potash remained concentrated (Matthews, 1970). The main 

prerequisites for potash deposition are for the water to become 

sufficiently concentrated with respect to potash and for the 

water to remain undiluted by outflow from the depositional 

basin (Matthews, 1970). In the Michigan Basin, the greatest 

potash thicknesses occur in what were the deepest parts of the 

seaway. A conceptual model of evaporite formation from a 

closed or restricted ocean basin is shown in figure 6. 

The evaporite deposit in the Michigan Basin covers an 

area of 33,670 km2 (Anderson and Egleson, 1970). The deposit 

is bordered on the northwest by the Wisconsin arch and on the 

southeast by the Cincinnati arch. The Findley and Algonquin 

arches form the northeast basin margin. During the middle 

Evaporation

 Calcite 

Gypsum/anhydrite 

 Potash salts 

 Halite 

Increasing 

solubility—

Potash is last to 

precipitate

Figure 6. Conceptual model of brine formation from an epeiric seaway inundating a closed or restricted basin. Mineral precipitation 

sequence shown by straight arrow and described in Garrett (1996). First formed is calcite. Potash is the most soluble in this sequence, 

so it precipitates last. Potash (sylvite) is commonly intergrown with halite (see fig. 4).
Geologic Setting and Geographic Distribution of Potash 13

Silurian, the Kankakee arch developed across northeastern 

Illinois. Although it did not form a land barrier, it greatly 

restricted circulation of seawater within the Michigan Basin.

Potash deposits formed during retreat and evaporation of 

a Silurian inland sea (fig. 7). Wells drilled in the central part of 

the basin intersect potash-bearing rocks of the Silurian Salina 

Group at depths of between 2,134 and 2,743 m. 

Potash salts can be distinguished from other salts 

using gamma ray technology. Salts without potassium lack 

a radioactive signature. The radioisotope 40K that is present 

in potash salts can be used to identify deposits. The potashbearing zone of the Salina Group is estimated to be at a 

depth greater than 152 m and was measured using gamma 

ray and mechanical well logs (Anderson and Egleson, 1970; 

Matthews, 1970). Gamma ray logs for the Salina Group and 

the A-1 evaporite, a term used locally to define the potashbearing stratigraphy, show that the potash is in multiple 

intervals (Elowski, 1980). Because of the great depths of the 

potash strata, in situ solution mining is the only economically feasible potash mining method in the Michigan Basin. 

The primary interval targeted for solution mining is the top 

of the A-1 evaporite known informally as the “Borgen Bed” 

occurring within the Salina Group stratigraphic sequence. 

Some layers of the “Borgen Bed” are reported to be of 

especially high purity containing 70 to 100 percent potassium chloride by volume. The potash deposit in the Michigan 

Basin is fortuitously located in the agricultural region of the 

United States where soy and corn are grown. 

Figure 7. Paleogeographic reconstruction of western North America during the late 

Silurian (Modified from Blakey, 2011). Michigan Basin area and adjacent Great Lakes 

area were inundated by a Silurian inland sea. (Copyright by Ron Blakey, Colorado 

Plateau Geosystems, used with permission.)

Michigan 

Basin
14 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

Williston Basin, North Dakota

Possibly the largest known but unexploited potash 

resources in the United States are within the Devonian strata 

of the Williston Basin. The Williston Basin is the southernmost extension of the Canadian Elk Point Basin, which hosts 

some of the largest mined potash deposits in the world. The 

Williston Basin is an intracratonic basin characterized by slow 

and moderate subsidence (Xie and Heller, 2009). This gradual 

subsidence may have produced conditions more favorable for 

evaporation and brine concentration compared to basins that 

subsided more rapidly. The inflow of seawater into the basin 

was restricted by carbonate reefs that developed during the 

Middle Devonian and with reefs that formed over intra-basin 

structural highs; the restricted inflow, coupled with an arid 

climate, enhanced brine formation (Anderson and Swinehart, 

1979) (fig. 8). 

The Williston Basin is located in eastern Montana, 

western North Dakota, northern South Dakota, and southern 

Saskatchewan (Canada). The basin is bordered on the east by 

the Canadian Shield and to the southeast by the Sioux uplift. 

The western and southwestern parts of the basin are defined by 

the Black Hills uplift, the Miles City arch, and Bowdoin dome. 

Basin deposits consist of a 4,877-m sequence of Cambrian 

through Holocene sedimentary rocks. The potash that formed 

in the Devonian Prairie Formation ranges in thickness from 13 

to 16.8 m. Five potash-bearing zones have been identified in 

the Prairie Formation using gamma ray logs (Kruger, 2014). 

Total potash resources throughout the Williston Basin are 

estimated to be 50 billion metric tons (Anderson and Swinehart, 1979). Potash beds occur at depths between 1,707 m and 

greater than 3,810 m (Kruger, 2014); these great depths limit 

recovery of potash to in situ solution mining methods. 

Figure 8. Paleogeographic reconstruction of western North America for the Middle Devonian 

(Modified from Blakey, 2011). Williston Basin in North Dakota is the southern extension of the potash 

deposits in the Elk Point Basin in Saskatchewan Province, Canada. (Copyright by Ron Blakey, Colorado 

Plateau Geosystems, used with permission.)

 Williston 

 Basin
Mining Methods for Potash 15

Nontraditional Potential Geologic Sources of 

Potassium for Fertilizer

Silicate rocks and minerals at or near the Earth’s surface 

are another, albeit non-traditional, source of potash. Early in 

the 20th century, a report by Schulz and Cross (1912) suggested the possible use of nepheline-bearing rocks that are 

high in potassium as a source of fertilizer. Nepheline is a 

relatively rare, rock-forming mineral that is found in large 

quantities in only a few U.S. localities (Schulz and Cross, 

1912). The Schulz and Cross (1912) report identified the challenges the United States faced at that time for obtaining potash 

from overseas sources. The Schulz and Cross (1912) report 

was written prior to the discovery of the potash-bearing saline 

lake deposits at Searles Lake and the Bonneville Salt Flats, 

and New Mexico’s 1925 Delaware Basin find. The report, 

however, demonstrated how eagerly scientists were searching 

for domestic sources of a vitally important industrial mineral. 

Since the discovery of massive potash deposits in the western 

United States and the Saskatchewan Province of Canada, the 

United States has not experienced a potash shortage. Other 

countries are not so fortunate, however. According to Orris 

and others (2014), much of Africa, Australia, and India lack 

either natural deposits or the ability to purchase potash from 

supplier countries. 

Currently, the potash deficit is particularly severe in 

Africa, which has few developed naturally occurring potash 

salt resources. In addition, the high cost of potash fertilizer 

prevents poor regions in Africa from acquiring sufficient 

potash for agricultural applications (Sheldrick and others, 

2002). Newly discovered deposits in Eritrea may soon help to 

alleviate the potash deficit in parts of Africa (Al Rawashdeh 

and others, 2016). Nonetheless, if potash derived from silicate 

minerals is found to be an effective alternative fertilizer to 

augment or replace traditional forms of potash salts, the 

economic burden on countries now required to import potash 

to sustain their agricultural industry could be lessened (Ciceri 

and others, 2015).

Studies in the early 21st century have been conducted 

to determine if accessible potassium-silicate deposits may 

be suitable for agricultural applications. Selected studies 

have shown that crop yields respond favorably when crushed 

potassium-bearing minerals are applied. Soils treated with 

the silicate mineral biotite were as productive as soils treated 

with potash (Mohammed and others, 2014). Soils amended 

with the mineral nepheline were slightly less productive and 

released potassium more slowly (Mohammed and others, 

2014). Field trial results of potassium-bearing silicate minerals in agricultural environments have been inconsistent and 

are not well documented. Standardized, well-documented 

field and laboratory tests are needed so that experimental 

results can be compared. Standardized field trials will aid 

in assessing the solubility and bioavailability of potassium 

derived from silicate minerals (Kristiansen and others, 2006; 

Manning, 2010). 

Mining Methods for Potash

Potash can be mined or harvested using several underground and surface methods. Mining methods discussed in 

this report are (1) traditional underground mining of potashbearing strata, (2) solar evaporation in surface ponds of brine 

sourced from groundwater or saline lakes, and (3) in situ solution mining of underground potash strata followed by solar 

evaporation in surface ponds.

Underground Mining Methods

The Carlsbad, New Mexico, potash deposits are at depths 

amenable to underground mining and accessed by vertical 

shafts between 198 and 533 m below the surface (Austin, 

1980) (fig. 9A). 

The Carlsbad deposits that are considered mineable 

contain a minimum of 10 percent potassium oxide in sylvite, 

or 4 percent potassium oxide in langbeinite. The Moab, Utah, potash deposit was mined by the underground method in the 

1960s, but the Carlsbad deposits are the only U.S. potash 

deposits currently mined underground.

A 75-year mining legacy at the Carlsbad potash mine 

has generated significant mine waste at the surface (fig. 9B). 

A primary geoenvironmental issue related to potash mining 

is the weathering of mine waste. Weathering of potash waste 

produces brine that may migrate from the waste site to nearby 

streams and soils and can be toxic to vegetation and aquatic 

life. A relatively dry climate near Carlsbad helps to mitigate 

waste weathering and reduce brine mobility. 

The Carlsbad potash deposits differ from the nonstratiform potash-bearing salts of Moab, Utah. The potash at 

Carlsbad is in multiple, nearly flat, continuous beds that can 

be mined using a continuous mining machine. Continuous 

miners can extract sylvite-rich, gently dipping strata along 

miles of strike (fig. 10A–E). A two-person crew operating a 

remotely controlled continuous mining machine and a loading 

car (fig. 10E) can mine as much as 600 to 1,000 metric tons 

of ore per 12-hour shift. Due to the precision of the mining 

equipment and skill of the operator, the continuous miner can 

avoid impure layers containing clay, salt, or dolomite and 

extract only high purity ore. Underground mining of potash 

is still profitable in the Carlsbad region today, making this 

one of the longest operating underground potash mines in the 

United States.
16 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

A

B

C

Figure 9. Photos of Intrepid Potash Company’s surface operations, Carlsbad, New Mexico. A, Site of original, early 1930s 

headframe over a vertical shaft (see Underground Mining Methods section of this paper) for Intrepid Carlsbad west mine. B, View 

northeast of mine waste pile. Potash processing plant at photo left. C, Solar evaporation ponds to capture brine leachate from the 

Carlsbad HB In Situ Solution Mine. Eighteen-pond complex is approximately 2 square kilometers. 
Mining Methods for Potash 17

Figure 10. Photos of underground mining operations, Carlsbad, New Mexico, Intrepid Potash Company, Carlsbad West Mine. 

A, Carbide steel-tipped drum on front of continuous miner. B, Active mining of potash layer by drum at mine face. C, Ore conveyor 

transfer system as part of continuous miner. D, Sylvite ore pillar (approximately 2.4 meters tall). Sylvite reddish to pink; gray bands 

are impurities formed during deposition. E, Loading vehicle (left) receiving ore from conveyor while ore face is being mined (far right). 

Grooves on mine back from continuous miner drum nibs.

A B

C D

E
18 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

Potash Recovery from Lacustrine and 

Groundwater Brines Through Solar Evaporation

Solar evaporation is used today to concentrate and harvest potash from Great Salt Lake brines. Sequential evaporation of Great Salt Lake brine in multiple manmade ponds 

concentrates halite first. Once halite has precipitated, the 

remaining brine becomes concentrated in the potassium salts 

kainite and carnallite. Kainite is a source of potassium sulfate. 

Potassium sulfate, referred to as SOP, is important for use as a 

fertilizer for chloride-intolerant crops including some fruit and 

nut varieties. The Compass Minerals Great Salt Lake operation supplies most of the U.S. domestic SOP and about 20 

percent of global exports (Joseph Havasi, Compass Minerals, 

oral commun., 2015). 

The Compass Minerals solar evaporation ponds are 

strategically located for optimal potash recovery. Conditions 

favorable for concentration of potash are due, in part, to the 

physical separation of the lake water that occurred when the 

1904 Southern Pacific railroad trestle was replaced with a new 

solid fill railroad embankment in 1959. The new embankment, constructed of rock and earthen fill, bisects the lake into north 

and south arms and prevents mixing between the two arms so 

the north arm has become more saline. Compass Minerals has 

constructed more than 200 km2 of manmade ponds near the 

northern arm of the Great Salt Lake to collect and evaporate 

brine (fig. 11A).

A geoengineered hydraulic feature known as the Behrens trench (named after former Great Salt Lake Minerals’ 

vice chairperson, Peter Behren) was constructed parallel to 

and north of the railroad embankment. Behrens trench was 

designed to transport higher density brine from Compass Minerals’ northwest ponds to solar evaporation ponds and a processing plant located near the northeast lake margin (fig. 11A). 

Pond water from the northwestern evaporation pond complex 

is transferred through a pump station to the trench (fig.11 B, 

C, and D). The Behrens trench allows the higher density brine 

to flow by gravity from west to east, even when lower density 

brine lake water overlies the hydraulic trench. 

Solar evaporation is also used to recover potash from 

high-salinity groundwater that is pumped to the surface. At the 

Bonneville Salt Flats (fig. 12A), Intrepid Potash pumps brine 

from shallow and deep groundwater wells to a primary canal 

(fig. 12B and C). Water from the primary canal is transferred 

to a series of solar evaporation reservoirs (fig. 12D and E). 

When potassium in the first evaporative reservoir reaches a 

specific level of concentration, the water is transferred to a 

second reservoir. The evaporative process continues through 

a series of water transfers with each transfer producing a 

higher potassium concentration. When water achieves potassium saturation in a final-stage “ripening” reservoir, and prior 

to magnesium chloride precipitation, water is transferred to 

a potassium-harvesting reservoir. The harvesting reservoir is 

subsequently drained and the precipitate allowed to dry. 

Solar evaporation to recover potash is favored by cool, 

wet winters and hot, dry summers with high solar evaporation 

rates. The entire cycle from pumping to transport to sequential 

solar evaporation can take more than one year (Eric Rogers, 

Intrepid Potash, oral commun., 2015). Relatively fresh water, 

derived from groundwater originating beneath the Silver 

Island Mountains to the north, serves as rinse water for brine 

transfer ponds and ditches. 

A series of processing steps involving flotation-cell concentration, centrifugation, kiln drying, and sieving are used to 

make multiple products suitable for use as fertilizer for homeand agricultural-scale use. Producing high-grade potash is a 

slow and precise process.

Conversion of Underground Mining to In Situ 

Solution Mining

The Cane Creek Mine, west of Moab, Utah, is operated 

as an in situ solution mine by Intrepid Potash, Inc. The Cane 

Creek Mine was initially operated in the 1960s as a traditional 

underground mine. However, since the Cane Creek potash beds 

formed in a salt dome, they are discontinuous and contorted so 

the mine operator converted the Cane Creek property to a more 

suitable in situ solution mine. A water-based brine solution is 

injected into the potash-bearing beds through intersecting drill 

holes. The injected solution leaches the soluble potash and the 

leachate is pumped to solar evaporation ponds at the surface 

using recovery drill holes. Potassium is concentrated in a series 

of solar evaporation ponds until an optimal potassium concentration is achieved prior to harvesting (fig. 13).

Typical potash deposits that are leached at Cane Creek 

are shown in figure 4C. The evaporated potash is shipped 

directly from the mine site by rail car to the midwestern 

United States for agricultural use.

Traditional underground mining of potash does not 

extract all of the available resource since underground pillars 

containing high-grade ore must be left as infrastructure to stabilize the mine workings. Solution mining is used to recover 

the ore left behind as pillars and to leach potash from unmined 

strata. Today, Intrepid Potash has converted the traditional 

underground workings of the former Eddy Potash Mine to 

an in situ solution mining operation (Berg, 2012; Bureau of 

Land Management, 2015). The renamed HB In Situ Solution 

Mine is located 32.18 kilometers northeast of Carlsbad, New 

Mexico, only a few kilometers from the Carlsbad underground 

potash workings (fig. 9A–C). 

Primary In Situ Leach Solution Mining

When the cost of underground mining is prohibitive, in 

situ solution mining may be an economical alternative. An 

in situ mine is located in Hersey, Michigan. Until November 

2013, this deposit was in situ solution mined by The Mosaic 

Company. At this locality, geologic units containing potash 

are exposed at or near the Michigan Basin margins where in 

situ wells have been installed. As with the Cane Creek Mine 

in Utah, injection wells serve as conduits for brine solutions 
Mining Methods for Potash 19

Figure 11. Photos of Compass Minerals Company, Great Salt Lake west ponds, potash solution transfer, and conveyance system. 

A, View north of west pond (approximately 11.3 kilometers wide); arrow is location of photos B and C. B, Pump system for transfer 

of west pond water to Behrens trench. C, View southeast of Behrens trench. D, View north of Behrens trench with dashed arrow 

showing trend of trench. Solid arrow is location of photos B and C. Trench continues eastward toward east ponds.

A

B C

D
20 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

Figure 12. Photos of solar evaporation operations for potash recovery at the Intrepid Potash Company, Wendover, Utah, site. 

A, View north of Bonneville Salt Flats under which groundwater brine is sourced (Silver Island Mountains in distance). B, View north 

of approximately 3.2 kilometer-long central canal where groundwater brine is collected. C, Pump station for groundwater brine 

transfer from central canal. D, Transfer pipes from central canal. E, Transfer of brine to Pond 1 for start of solar evaporation and 

potash concentration. Pond 1 is about 2.4 kilometers wide by 1.8 kilometers long and is one of multiple ponds constructed onsite.

A

B

C

D E
Import-Export Supply Chain—Current and Projected Use 21

Figure 13. Photo showing Intrepid Potash Company’s solar evaporation ponds near Moab, Utah (view toward the east). Ponds are 

on an upper member of the Permian Cutler Formation. Red beds to east of ponds are Cutler Formation at base, overlain by Triassic 

Moenkopi and Chinle Formations and cliff-capping Jurassic Wingate Sandstone (Doelling and others, 1994). Anticlinal fold (northeast 

limb of Cane Creek salt anticline) gently dipping red beds at left (arrow). High peaks in the distance are the La Sal Mountains.

used to dissolve potash-bearing strata that are intersected at 

moderate depths. Recovery wells drilled near the sites of brine 

injection permit potash-bearing leachate to be pumped to the 

surface, evaporated, and processed.

Past and Current Potash Production

A large increase in U.S. potash production corresponds 

with the 1925 discovery and development of potash in the 

Delaware Basin near Carlsbad, New Mexico, with 126,000 

metric tons of potash (K2O equivalent) being produced by 

1933 (Kelly and Matos, 2013). Potash production in the 

United States peaked in 1966 when 2,840,000 metric tons of 

potash (K2O) were produced primarily from the New Mexico 

deposits (fig. 14).

Mining of Canadian deposits commenced in the Saskatchewan Basin and in New Brunswick around 1958. Potash production in the United States peaked about 10 years after initial 

development of these large Canadian deposits. The Canadian 

potash resources are the largest known in the world and have 

been the primary global source since their discovery. Between 

1958 and 1988, a fourfold increase in global production 

occurred, which corresponded with a twofold decrease in U.S. 

production. A graph comparing domestic and world potash 

production between 1918 and 2011 is provided in figure 15. 

Import-Export Supply Chain—Current 

and Projected Use

Manning (2010) estimated that global potash production must double to satisfy the projected need in Africa alone. 

Potash was found to be most prone to depletion in agricultural 

soils in Africa when compared with phosphorus and nitrogen (Manning, 2010). This fact highlights the importance of 

potash in the global supply chain, especially for economically 

challenged or developing countries that lack local potash 

resources. In addition to cropland use, potash will also be 

needed to restore areas disturbed by anthropogenic uses to 

healthy functioning ecosystems. It is projected that sufficient 

potash will be available to meet worldwide demand; however, 

traditional sources of potash salts are found concentrated in 

only a few geographic regions including, in descending order 

of total production, Canada, Russia, Belarus, China, and 

Germany. Figure 16 provides potash production data for the 

highest producing countries in 2012 and 2013.

Production data for 2011 (Jasinski, 2011) show that Canada is the major global potash producer. Russia, China, and 

the European countries of Belarus and Germany, also produce 

large quantities of potash (fig. 16). The Middle Eastern countries of Israel and Jordan together produce three times more 

potash than the United States (Jasinski, 2011). Chile and the 

United States produce approximately equal volumes of potash 

annually. England, Spain, and Brazil have the lowest potashproducing areas. These data highlight the limited geographic 

distribution of potash sources, which could affect the global 

supply chain. Potash reserves are estimated to be greatest in 

Canada, Belarus, and Russia (fig. 17). The data indicate that 

Brazil has larger potash reserves than its current low annual 

production might suggest (figs. 16 and 17).

A stable trade relationship between the United States and 

Canada likely ensures an uninterrupted supply of potash to 

the United States. Political uncertainty and subjective trade 

agreements in other regions of the world can, and sometimes

do, interfere with potash import-export markets. It is clear that 

the U.S. potash supply is currently stable since Canada’s large 

potash deposits are available for import. In contrast, possible 

political unrest in Europe, Asia, the Middle East, or Russia 

could interfere with distribution of potash resources to nations 
22 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

0

 0.5

 1.0

 1.5

 2.0

 2.5

 3.0

 3.5

1912 1932 1952 1972 1992 2012

Year

U.S. potash production (millions of metric tons K2O)

Figure 14. Graph showing U.S. potash production between 1915 and 2012. 

Production peaked in 1966 at 2.84 millions of metric tons potassium oxide (K2O). 

(Kelly and Matos, 2013).

Figure 15. Graph comparing U.S. (black solid line) and world potash 

production (blue dashed line) between 1918 and 2011. Data are 

reported in millions of metric tons potassium oxide (K2

O) equivalent 

(Kelly and Matos, 2013).

Year

1915

40

35

30

25

20

15

10

5

0

1935 1955

Domestic

World

1975 1995 2015

Potash production (millions of metric tons, K2O)
Import-Export Supply Chain—Current and Projected Use 23

0

 2

 4

 6

 8

 10

 12 Potash production (millions of metric tons K2O)

2012

2013

Belarus

Brazil

Canada

Chile

China

Germany

Israel

Jordan

Russia

Spain

United Kingdom

United States

Figure 16. Graph showing global potash production for 2012 and 2013 reported as 

potassium oxide (K2O) (U.S. Geological Survey, 2015).

Figure 17. Graph showing global potash reserves in potassium oxide (K2

O) 

equivalent (U.S. Geological Survey, 2015).

0

 200

 400

 600

 800

 1,000

 1,200 Potash reserves (millions of metric tons K2O)

Belarus

Brazil

Canada

Chile

China

Germany

Israel

Jordan

Russia

Spain

United Kingdom

United States

Other countries
24 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

that depend on these potash sources. Potash is but one of many 

examples of how the geographically limited occurrence of a 

mined commodity can be a contributing factor to the availability of a commodity. 

Periods of global economic downturn or recession have 

been mirrored by a decrease in global potash production. For 

example, global decreases in potash production were observed 

during the 1991–1993 and 2009 global recessions. In 2009, 

U.S. potash imports declined by more than half compared to 

the previous year (fig. 18).

The ratio of U.S. domestic to world production shows a 

slight increase in domestic production in 1992 followed by a 

gradual decline as economic recovery continued to be sluggish 

through the remainder of the decade (fig. 19).

Overall, the domestic to world production ratio of potash 

illustrates the abrupt decrease in U.S. production when the 

Canadian deposits were discovered in 1958. Canada replaced 

the United States as the world’s main supplier of potash during 

this time. In addition, figure 16 illustrates the world domination of potash production compared to that of the United States 

(U.S. Geological Survey, 2015). 

Estimates of global reserves indicate that there is sufficient supply to meet current and future global demand (U.S. 

Geological Survey, 2015). Although there is no foreseeable 

shortage of potash, not all countries can afford to buy or 

distribute the commodity. It can be challenging for countries 

to pay $500 per metric ton, the calculated five-year average 

cost, for potash. According to USDA data charts, one U.S. acre 

of wheat tillage requires 9.5 kg of potash and one U.S. acre of 

soybean tillage needs about 34 kg of potash (http://www.ers.

usda.gov). Due to the irregular distribution of potash deposits 

and business organizations that have controlled the price of 

potash on global markets, potash prices peaked at historically 

high levels in February 2009 at $875 per metric ton (fig. 20). 

The 52-week price range as of August 2014 ranged from $287 

to $393 per metric ton. 

The global distribution of potash deposits can be a limiting factor in a country’s ability to have adequate fertilizer supplies. Many countries in Africa, for example, lack sufficient 

potash resources to meet projected demand for agricultural 

applications (Manning, 2010). Other factors that may make it 

difficult for African countries to obtain adequate supplies of 

potash are the price of the commodity and the global distribution of potash reserves. Even if countries can afford the commodity, they may lack the infrastructure or mechanism for its 

distribution (Manning, 2010). Therefore, even though potash 

may be abundant, it may still be unavailable to much of the 

world. Many African nations are economically poor and lack 

resources to purchase potash, especially when the market price 

is high. Large potash deposits of the marine type only occur 

in a few areas of the world. Any commodity that has such 

an uneven distribution is subject to socio-political unrest if 

demand exceeds or pressures the supply. For example, the current political situation in Ukraine possibly makes the potash 

deposits there less readily available for distribution locally and 

on the global market. 

0

 1

 2

 3

 4

 5

 6

 7

1900 1920 1940 1960 1980 2000

 Potash imports (millions of metric tons, K2O)

Year

Figure 18. Graph showing U.S. potash imports between 1900 and 2012 reported 

as potassium oxide (K2O) (Kelly and Matos, 2015).
Import-Export Supply Chain—Current and Projected Use 25

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

1918 1928 1938 1948 1958 1968 1978 1988 1998 2008

Ratio of U.S. to world potash production

Year

0

100

200

300

400

500

600

700

800

900

1,000

1960196119621963196419651966196719681969197019711972197319741975197619771978197919801981198219831984198519861987198819891990199119921993199419951996199719981999200020012002200320042005200620072008200920102011201220132014

Price of muriate of potash in U.S. dollars per metric ton

Production year

Figure 19. Graph showing ratio of U.S. to world potash production between 1919 and 2011 (Kelly and 

Matos, 2015).

Figure 20. Graph showing price of muriate of potash between 1960 and 2014. Solid black line is actual price; dotted 

black line is 12-month yearly average adjusted to 2010 U.S. dollars. (Modified from World Bank, 2016).
26 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

Summary

Potash is a geologically sourced essential nutrient. While 

silicate minerals have shown promise as an alternative source 

of potash for agricultural use, potash salts remain the primary commodity for this purpose in the foreseeable future. 

The distribution of large, Paleozoic-age potash salt deposits 

is controlled by global seas that encroached on the interior 

North American continent. Seaway retreat, restriction from 

inflow or outflow of seawater, and evaporation resulted in the 

formation of extensive potash deposits. The Delaware Basin 

of New Mexico, Michigan Basin, Paradox Basin of Utah, 

and Williston Basin of North Dakota are examples of marinetype deposits. Marine-type deposits are primarily mined as a 

source of muriate of potash. Quaternary brine derived from 

continental interior lakes such as the Great Salt Lake in Utah 

is an important source of sulfate of potash that is used as a soil 

amendment for chloride-intolerant crops. Groundwater brine 

that is a remnant of the large Pleistocene Lake Bonneville 

continues to be an important U.S. source of potash at Wendover, Utah. In situ solution mines that have been converted 

from underground mines, such as the HB In Situ Solution 

Mine project in Carlsbad, New Mexico, and the Cane Creek 

Mine in Grand County, Utah, are viable potash operations 

that are producing today. Known, extensive potash reserves 

that are too deep for conventional underground mining (such 

as those in the Michigan and Williston Basins) are potential 

sources of potash that could be mined using the in situ solution mining method. While current estimated potash reserves 

can supply all the global demands for the foreseeable future, 

potash reserves are geographically limited to specific regions. 

The limited geographic distribution of potash salts, the price 

of the commodity, a government’s infrastructure and ability to 

distribute potash, and political unrest can all affect a country’s 

ability to obtain and use this essential nutrient. 

References

Al Rawashdeh, R., Xavier-Oliveira, Emanuel, and Maxwell, 

Philip, 2016, The potash market and its future prospects: 

Resources Policy, v. 47, p. 154–163.

Anderson, R.J., and Egleson, G.C., 1970, Discovery of potash 

in the A-1 Salina salt in Michigan, in Kneller, W.A., ed., 

Miscellany 1, Papers Presented at the Sixth Forum on Geology of Industrial Rocks and Minerals: Lansing, Michigan, 

State of Michigan Department of Natural Resources, p. 

9–12. 

Anderson, S.B., and Swinehart, R.P., 1979, Potash salts in the 

Williston Basin, U.S.A.: Economic Geology, v. 74, no. 2, 

p. 358–376.

Anderson, W.L., 1957, Geology of the northern Silver Island 

Mountains, Box Elder and Tooele Counties, Utah: University of Utah , Department of Geology, M.S. Thesis, 131 p.

Armstrong, D.L., ed., 1998, Potassium for agriculture: Better 

Crops With Plant Food, v. 82, no. 3, 39 p. 

Austin, G.S., 1980, Potash in New Mexico: New Mexico 

Geology, v. 2, p. 7–9.

Baligar, V.C., Fageria, N.K., and He, Z.L., 2001, Nutrient use 

efficiency in plants: Communications in Soil Science and 

Plant Analysis, v. 32, no. 7–8, p. 921–950.

Barker, J.M., Gundiler, Ibrahaim, and Walsh, Patrick, 2008, 

New Mexico potash—Past, present, and future: New Mexico Bureau of Mines and Bureau of Geology and Mineral 

Resources, New Mexico Earth Matters, v. 8, no. 2, 6 p.

Berg, W. R., 2012, Regional geology—Geology and minerals issues related to the proposed HB in-situ solution mine 

project, in HB In-Situ Solution Mine Project Final Environmental Impact Statement, 2012: Bureau of Land Management, DOI–BLM–NM–P020–2011–498–EIS, accessed 

November 13, 2014 at http://www.nm.blm.gov/cfo/HBIS/

finalEIS.html.

Bingham, C.P., 1980, Solar production of potash from the 

brines of the Bonneville Salt Flats: Utah Geological and 

Mineral Survey Bulletin 116, p. 229–242. 

Blakey, R.C., 1979, Lower Permian stratigraphy of the 

southern Colorado Plateau, in Baars, D.L., ed., Permianland—Four Corners Geological Society Field Conference, 

9th: Durango, Colorado, Four Corners Geological Society, 

p. 115–129.

Blakey, R.C., 1990, Stratigraphy and geologic history of 

Pennsylvanian and Permian rocks, Mogollon Rim region, 

central Arizona and vicinity: Geological Society of America 

Bulletin v. 102, no. 9, p. 1189–1217.

Blakey, R.C., 2011, Paleogeography of Western North 

America: Colorado Plateau Geosystems, Inc., Western 

North America series, 1 CD-ROM, accessed July 1, 2016, at 

https://www2.nau.edu/rcb7/RCB.html.

Bureau of Land Management, 2015, HB in-situ project environmental impact statement: U.S. Bureau of Land Management, accessed July 15, 2015, at http://www.nm.blm.gov/

cfo/HBIS/overview.html.

Ciceri, D., Manning, D.A.C., and Allanore, A., 2015, Historical and technical developments of potassium resources: 

Science of the Total Environment, v. 502, p. 590–601.

Craig, M.S., Jol, H.M., Teitler, Lora, and Warnke, D.A., 2012, 

Geophysical surveys of a pluvial lake barrier deposit, Beatty 

Junction, Death Valley, California, USA: Sedimentary Geology, v. 269–270, p. 28–36.
References 27

Davis, F.D., comp., 1983, Geologic map of the southern 

Wasatch Front, Utah: Utah Geological and Mineral Survey 

Map 55–A, 2 sheets, scale 1:100,000.

Domagalski, J.L., and Eugster, H.P., 1990, Trace metal geochemistry of Walker, Mono, and Great Salt Lakes: The Geochemical Society, Special Publication No. 2, p. 315–353.

Elowski, R.C., 1980, Potassium salts (potassium) of the Salina 

A–1 evaporite in the Michigan Basin: Michigan Department 

of Natural Resources, Report of Investigation 25, 14 p.

Fountain, D.M., and Christensen, N.I., 1989, Composition of 

the continental crust and upper mantle—A review: Geological Society of America Memoirs 172, p. 711–742.

Garrett, D.E., 1996, Potash deposits, processing, properties, 

and uses: London, Chapman and Hall, 734 p. 

Giambastiani, M., and Bullard, T.F., 2010, Terminal Pleistocene—Early Holocene adaptations on the eastern shore of 

China Lake, California, in Kaldenberg, R.L., ed., Archaeology of Naval Air Weapons Station, China Lake, California: 

Pacific Coast Archaeological Society Quarterly, v. 43, no. 

1–2, p. 50–70.

Gill, Dan, 1977, Salina A–1 sabkha cycles and the late Silurian 

paleogeography of the Michigan Basin: Journal of Petrology, v. 47, no. 3, p. 979–1017.

Hayes, P.T., 1964, Geology of the Guadalupe Mountains, New 

Mexico: U.S. Geological Survey Professional Paper 446, 

69 p.

Hite, R.J., 1961, Potash-bearing evaporite cycles in the salt 

anticlines of the Paradox Basin, Colorado and Utah in Short 

paper in hydrologic and geologic sciences: USGS Professional Paper 424-D, p. D135–D138.

Intrepid Potash, 2013, Annual Report, Form 10–K: Washington, 

D.C., United States Securities and Exchange Commission. 

Jarrett, R.D., and Malde, H.E., 1987, Paleodischarge of the 

late Pleistocene Bonneville flood, Snake River, Idaho, computed from new evidence: Geological Society of America 

Bulletin, v. 99, p. 127–134.

Jasinski, S.M., 2011 [2013], Potash, in U.S. Geological Survey 

Minerals Yearbook—2011: U.S. Geological Survey, p. 

58.1–58.5, accessed April 23, 2015, at http://minerals.usgs.

gov/minerals/pubs/commodity/potash/myb1-2011-potas.pdf.

Jones, C.L., and Madsen, B.M., 1968, Evaporite geology 

of the fifth ore zone Carlsbad district, southeastern New 

Mexico: U.S. Geological Survey Bulletin 1252–B, 21 p.

Kelly, T.D., and Matos, G.R., comps., 2013, Historical statistics for mineral and material commodities in the United 

States (2013 version): U.S. Geological Survey Data Series 

140, accessed July 15, 2015, at http://minerals.usgs.gov/

minerals/pubs/historical-statistics/.

Kristiansen, Paul, Taji, Acram, and Reganold, J.P., eds., 2006, 

Organic agriculture—A global perspective: Australia, 

CSIRO publishing, 480 p.

Kruger, Ned, 2014, The potash members of the Prairie Formation in North Dakota: North Dakota Geological Survey 

Report of Investigations no. 113, 39 p.

Lowenstein, T.K., 1988, Origin of depositional cycles in a 

Permian “saline giant”—the Salado (McNutt zone) evaporates of New Mexico and Texas: Geological Society of 

America Bulletin v. 100, p. 592–608.

Manning, D.C., 2010, Mineral sources of potassium for plant 

nutrition—A review: Agronomy for Sustainable Development, v. 30, p. 281–294.

Matthews, D.R., 1970, The distribution of Silurian potash in 

the Michigan Basin, in Kneller, W. A., ed., Miscellany 1, 

Papers presented at the Sixth Forum on Geology of Industrial Rocks and Minerals: State of Michigan Department of 

Natural Resources, Lansing, Michigan, p. 9–12.

Matthews, R.D., and Egleson, G.C., 1974, Origin and implications of a mid-basin potash facies in the Salina Salt 

of Michigan, in Coogan, A.H., ed.: Fourth International 

Symposium on Salt, v. 1, Northern Ohio Geological Society, 

p. 15–34.

Melotto, M., Underwood, W., Koczan, J., Nomura, K., and 

He, S.Y., 2006, Plant stomata function in innate immunity 

against bacterial invasion: Cell, v. 126, no. 5, p. 969–980.

Mohammed, S.M.O., Brandt, K., Gray, N.D., White, M.L., and 

Manning, D.A.C., 2014, Comparison of silicate minerals as 

sources of potassium for plant nutrition in sandy soil: European Journal of Soil Science, v. 65, p. 653–662.

Nuccio, V.F., and Condon, S.M., 2000, Burial and thermal 

history of the Paradox Basin, Utah and Colorado, and 

petroleum potential of the Middle Pennsylvanian Paradox 

Formation: U.S. Geological Survey Bulletin 2000–O, 41 p.

Orris, G.J., 2011, Deposit model for closed-basin potashbearing brines: U.S. Geological Survey Open-File Report 

2011–1283.

Orris, G.J., Cocker, M.D., Dunlap, P., Wynn, Jeff, Spanski, 

G.T., Briggs, D.A., and Gass, L., with contributions from 

Bliss, J.D., Bolm, K.S., Yang, C., Lipin, B.R., Ludington, 

S., Miller, R.J., and Slowakiewicz, M., 2014, Potash—A 

global overview of evaporite-related potash resources, 

including spatial databases of deposits, occurrences, 

and permissive tracts: U.S. Geological Survey Scientific 

Investigations Report 2010–5090–S, 76 p., and spatial 

data, accessed July 1, 2016 at http://dx.doi.org/10.3133/

sir20105090S.
28 Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits

Oviatt, C.G., 1987, Lake Bonneville stratigraphy at the Old 

River Bed, Utah: American Journal of Science, v. 287, 

p. 383–398.

Paynter, H.M., 1990, The first U.S. patent: American Heritage 

of Invention & Technology, v. 5, no. 3, p. 18–22.

Rauzi, S.L., 2000, Permian salt in the Holbrook Basin, Arizona: Arizona Geological Survey Open-File Report 00–03, 

20 p.

Rauzi, S.L., 2008, Arizona has potash: Arizona Geological 

Survey, v. 38, no. 2, p. 1–4.

Rudnick, R. L., and Gao, S., 2003, Composition of the continental crust, in Rudnick, R.L., ed., The Crust: Treatise in 

Geochemistry, v. 3, p. 1–64.

Schaeffer, F.E., 1960, Geology of the Silver Island Mountains: 

Utah Geological Society Guidebook 15, p. 169–175.

Schmalz, R.F., 1969, Deep-water evaporite deposition—A 

genetic model: The American Association of Petroleum 

Geologists Bulletin, v. 53, no. 4, p. 798–823.

Schulz, A.R., and Cross, Whitman, 1912, Potash-bearing rocks 

of the Leucite Hills, Sweetwater County, Wyoming: U.S. 

Geological Survey Bulletin 512, 39 p. 

Sheldrick, W.F., Syers, J.K., and Lingard, J., 2002, A conceptual model for conducting nutrient audits at national, 

regional and global scales—Nutrient cycling: Agroecosystems, v. 62, p. 61–67.

Smith, G.I., 2009, Late Cenozoic geology and lacustrine 

history of Searles Valley, Inyo and San Bernardino Counties, California: U.S. Geological Survey Professional Paper 

1727, 115 p.

Smith, G.I., and Haines, D.V., 1964, Character and distribution 

of nonclastic minerals in the Searles Lake evaporite deposit, 

California: U.S. Geological Survey Bulletin 1181–P, 59 p.

Spencer, R.J., Eugster, H.P., Jones, B.F., and Rettig, S.L., 

1985, Geochemistry of Great Salt Lake, Utah I—Hydrochemistry since 1850: Geochimica Cosmochimica Acta, v. 

49, no. 3, p. 727–737. 

Tripp, T.G., 2009, Production of magnesium from the Great 

Salt Lake, Utah, USA: Natural Resources and Environmental Issues, v. 15, article 10, p. 55–61, accessed April 13, 

2015, at http://digitalcommons.usu.edu/nrei/vol15/iss1/10.

Turk, L.J., Davis, S.N., and Bingham, C.P., 1973, Hydrogeology of lacustrine sediments, Bonneville Salt Flats, Utah: 

Economic Geology, v. 68, no. 1, p. 65–78.

Turrentine, J.W., and Shoaff, P.S., 1919, Potash from kelp—

The experimental plant of the United States Department of 

Agriculture, preliminary paper: Industrial and Engineering 

Chemistry, v. 11, p. 864–874.

U.S. Geological Survey, 2015, Mineral commodity summaries: U.S. Geological Survey, accessed July 15, 2015, at 

http://minerals.usgs.gov/minerals/pubs/commodity/potash/.

Wang, M., Zheng, Q., Shen, Q., and Guo, S., 2013, The critical role of potassium in plant stress response: International 

Journal of Molecular Sciences, v. 14, p. 7370–7390.

Warren, J.K., 2010, Evaporites through time—Tectonics, 

climatic and eustatic controls in marine and nonmarine 

deposits: Earth Science Reviews, v. 98, p. 217–268.

Williams-Stroud, S.C., 1994, The evolution of an inland sea 

of marine origin to a non-marine saline lake: the Pennsylvanian Paradox salt, in Renault, R.W., and Last, W.M., eds., 

Sedimentology and geochemistry of modern and ancient 

saline lakes: Tulsa, Okla., Society for Sedimentary Geology, 

Special Publication 50, p. 293–306.

World Bank, 2016, Global Economic Monitor (GEM) 

commodities: The World Bank Group, accessed 

July 1, 2016, at http://databank.worldbank.org/data/

reports.aspx?source=global-economic-monitor-(gem)-

commodities#.

Xie, X., and Heller, P.L., 2009, Plate tectonics and basin 

subsidence history: Geological Society of America Bulletin, 

v. 121, 55–64.

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Yager—Potash—A Vital Agricultural Nutrient Sourced from Geologic Deposits—Open File Report 2016–1167

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