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Potassium Sources

Elemental K is not found in nature because of its chemical reactivity. Potash deposits occur as beds of solid salts beneath the earth's surface and brines in dying lakes and seas.

Potassium is mined from a number of minerals. Sylvinite, sylvite and langbeinite are the most important.

- Sylvinite is composed primarily of potassium chloride (KCl) and sodium chloride (NaCl)-containing 20 to 30 percent K20.

- Sylvite is composed mainly of KCI, containing about 63 percent K20-

Langbeinite is composed largely of potassium sulphate (K2SO4) and magnesium sulphate (MgSO4)- containing about 23 percent K2O. (Brines containing K are about two-thirds water and contain about three percent K20)

Potassium chloride- Potassium Chloride, or muriate of potash, accounts for more than 90 percent of the K sold in the U.S. and Canada. It is water soluble and contains 60 to 62 percent K20- Most North American KCI is produced from sylvinite, but some comes from brines. The raw, impure ore is refined to fertilizer by crystallization or flotation processes. Most agricultural KCI is produced by the flotation process.

Fertilizer grade KCI is available in five particle sizes: (1) white soluble, (2) special standard, (3) standard, (4) coarse and (5) granular. Granular is very suited to bulk blending. The white soluble grade is ideal for clear liquids.

Potassium sulphate (K2SO4)- Also called sulphate of potash (SOP), contains about 50 percent K2O and 18 percent sulphur (S). Because its chloride (Cl) content is below 2.5 percent, it is used for Cl-sensitive crops such as tree fruits and tobacco, and to supply S. It accounts for about six percent of total agricultural K sales. Potassium sulphate can be used where Cl buildup becomes a problem.

Sulphate of potash-magnesia (K2SO4-2MgSO4)- It is also called potassium-magnesium sulphate, "Sul-PoMag" and "K-Mag.". It contains about 22 percent K20, 11 percent magnesium (Mg) and 22 percent S. It occurs in nature as the mineral, langbeinite, which is refined to the commercial fertilizer product. It is a good source of water-soluble K and Mg, and is very important where Mg and/or S is deficient.

Potassium nitrate (KNO3)- Potassium nitrate contains little or no Cl or S. It contains about 44 percent K20 and 13 percent N.

Composition of common potassium fertilizer sources:

Material K2O - % Mg - % S - % N - % Cl - %
KCl 60-62 - - - 45-47
K2SO4 50 - 18 - -
K2SO4-2MgSO4 22 11 22 - -
KNO3 44 - - 13 -

 

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News

A closed boll is seen on a cotton plant growing in a field.
Filed Under: Agricultural Economics, Cotton September 15, 2017

STARKVILLE, Miss. -- Rain, cool weather, more rain and some wind have slowed cotton maturation, but since the crop was a little behind schedule, the damage may be less than if harvest were already underway.

Darrin Dodds, cotton specialist with the Mississippi State University Extension Service, said recent weather is causing some yield loss, but it is hard to estimate how much.

“Being late to a degree helped the crop because rain did not string out open cotton, but given that we are running out of heat, we may have been better off with an earlier crop that had been defoliated and was standing up when the rain came,” Dodds said.

Mississippi Boll Weevil Management Corp. representative Mike Mullendore checks one of the cone-shaped traps located near a Mississippi State University research field on June 27, 2017. The traps evolved from U.S. Department of Agriculture research at the Robey Wentworth Harned Laboratory, commonly known as the Boll Weevil Research Lab at MSU. (Photo by MSU Extension Service/Linda Breazeale)
Filed Under: Cotton, Insects-Crop Pests August 24, 2017

STARKVILLE, Miss. -- Cotton will always have challenges, but few of them will ever compare to the boll weevils that thrived in Mississippi from 1904 until 2009.

“It is nearly impossible for this younger generation of consultants, scouts and growers to understand how hard boll weevils were to control and how much boll weevil control hurt beneficial insects and complicated cotton management,” said Will McCarty, who served as the Mississippi State University Extension Service cotton specialist during “the boll weevil wars.”

Award-winning farmer Paul Good examines cotton growing in Noxubee County during a Mississippi State University field tour on July 12, 2017. Good said he remembers a time when farmers did not grow cotton in the area, mostly because of boll weevils. (Photo by MSU Extension Service/Linda Breazeale)
Filed Under: Cotton, Insects-Crop Pests August 24, 2017

MACON, Miss. -- Farmers' independent natures make them strong, but when agricultural producers join forces, they can take success to the next level.

Darrin Dodds, cotton specialist with the Mississippi State University Extension Service, commended Mississippi farmers for their efforts to unite in the battle to eradicate boll weevils from the state.

“Historically, boll weevils were the prime pest in cotton fields. To control them, it took numerous pesticide applications,” he said. “Those treatments were costly and ate into the growers’ profit margins.”

Dark clouds move toward Mississippi State University soybean and corn plots at the R.R. Foil Plant Science Research Center in Starkville, Mississippi, on Aug. 17, 2017. (Photo by MSU Extension Service/Linda Breazeale)
Filed Under: Cotton, Grains, Rice, Soybeans August 18, 2017

STARKVILLE, Miss. -- Mississippi’s row crops have had enough rain, and most fields just need sunshine.

Erick Larson, grain crops specialist with the Mississippi State University Extension Service, said corn is mature and will gain no benefit from additional moisture. In the first couple of weeks of August, skies were overcast or rain was falling across most of the state.

Cotton across the state has been struggling with excess rainfall but remains in good shape at this point in the season. This cotton was growing in a saturated field June 22, 2017, at Mississippi State University in Starkville. (Photo by MSU Extension Service/Kevin Hudson)
Filed Under: Cotton June 23, 2017

STARKVILLE, Miss. -- Tropical Storm Cindy did not help the state's cotton crop that struggled with cool and wet weather all spring.

Darrin Dodds, cotton specialist with the Mississippi State University Extension Service, said in mid-June, cotton received about a week of the heat and sun it needs to thrive. Weather before that was not ideal, and rain remains in the forecast.

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