The
growth and quality of many crops around the world suffer due to an inadequate
supply of plant-available potassium (K) in the soil. IPNI has had a renewed emphasis
on the importance of K for crop nutrition through recent international
conferences and an upcoming book. The outputs of the 2017 IPNI Frontiers of
Potassium Science Conference are archived at https://conference.ipni.net/conference/kfrontiers2017/article/home.
It is timely to briefly review the
development of this important industry that supports the
global
food supply.
Potassium
salts have been valuable industrial chemicals for more than a thousand years,
where they are used in making glass, soap, paper, and textiles. Leaching K
salts from wood ash in vast hardwood forests in Russia and also harvesting kelp
from the coast of northern Europe (especially Scotland) were some of the early
sources of potash. Some of the kelp biomass was used as fertilizer, but most of
the harvested kelp was treated to collect concentrated potash for industrial
purposes.
Production
of potash was an important source of income for the early North American
colonies as forests were cleared and easy access to ports made shipping to
Europe feasible. The income derived from potash sales after clearing and burning
the forests often provided the necessary financial support during the first
years while a new farm was being established.
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| e.g. www.townshipheritage.com/Eng/Hist/Life/potash.html |
As
the essential nature of K for plant nutrition was recognized in the 19th
century, the demand for K fertilizer greatly expanded, leading to the
development of the potash fertilizer industry from geologic sources.
Large-scale K mining was made possible with technology from the industrial
revolution to make potash affordable and available for farmers.
The
early supply of mined potash was from the Stassfurt region of Germany, which
still has an active K mining industry. The potash trade between North America
and the German potash cartel was halted by World War I. This abrupt potash shortage
prompted urgent exploration for new K sources.Some of the North American K
resources developed in the early 1900’s include:
Nebraska:
Potash
was extracted from brines in the Western Sandhills of Nebraska. At the peak,
there were ten plants operating in the region, with a dedicated railroad line for
transportation.
California:
Kelp
harvesting was an important source of K during the early 1900’s. Kelp was also
a source of acetone, which was important for the war effort. Potassium and
boron-rich brines from the Searles Lake region were extracted for commercial
fertilizers and industrial chemicals.
New Mexico:
Commercially
valuable deposits were developed near Carlsbad, where potash mining continues
today. Other deposits were developed in Michigan and Utah.
Large
potash reserves were developed in the Ural Mountains of the Soviet Union in the
1930’s, and later in Belarus, adding to the global supply.
Following
World War II, the largest global deposits of potash were discovered at a depth
of 1,000 m or more in Saskatchewan, Canada, with commercial production
beginning
in
the 1960’s.
Significant
potash mining still continues in China, Germany, the Middle East, Chile, Spain,
and the U.K. There are pilot projects currently underway in many additional countries
that may bring additional potash fertilizer to the global marketplace.Potash
fertilizer largely comes from the minerals sylvite (KCl), sylvinite (KCl + NaCl),
and increasingly from polyhalite (K2SO4·MgSO4·2CaSO4·2H2O). A variety of other K-rich minerals
are mined or processed into potash fertilizer to meet the needs of individual
crops and soil conditions.
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| Potash ore from Canada (Red color from traces of iron) |
The
six countries that utilize the most potash are China, Brazil, United States,
India, Indonesia, and Malaysia who consume more than 70% of global production.
This usage reflects the native soil K supply and the K demand of the crops
grown in these countries.
Potassium
minerals are fairly common around the world and the estimated world resource is
about 250 billion metric tons. Despite the abundance of potash, it is always
appropriate to use all plant nutrients carefully and apply the principles of 4R
Nutrient Stewardship
Additional Reading
Ciceri,
D., D.A.C. Manning, and A. Allanore. 2015. Science of the Total Environment
502:590-601.
Mikkelsen,
R.L. and T.W. Bruulsema. 2005. Hort Technology 15:25-30.
Nelson,
L.B. 1990. History of the U.S. fertilizer industry. Tennessee Valley
Authority,
Muscle Shoals, AL
