Editor's Note — This is the third in a three-part series that explores the outlook for fertilizer for the 2009 cropping season.

Compared to nitrogen and phosphorus, potassium is harder to find, harder to process and less available on a global basis than nitrogen and phosphorus. For farmers that combination likely equates to uneven supply and up and down pricing for the 2009 season.

In the upper Southeast the use of phosphorus (P) and potassium (K) fertilizers has declined in the past few years as growers mined existing supplies that have accumulated from many years of over-use. The popularity of poultry litter and other organic sources of fertilizer has also created a decline in P and K usage as has the recent volatility in pricing of all fertilizers, including P and K.

Despite a couple of centuries of study, the exact function of K in plant growth has not been clearly defined. Potassium is associated with movement of water, nutrients, and carbohydrates in plant tissue. If K is deficient or not supplied in adequate amounts, growth is stunted and yields are reduced.

A summary of research over the past two decades indicates that K has the following impacts on crop plants:

  • Stimulates early growth.

  • Increases protein production.

  • Improves the efficiency of water use.

  • Is vital for stand persistence, longevity, and winter hardiness of cool weather crops.

  • Improves resistance to diseases and insects.

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

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.

Factors driving the availability and price of K for Southeast growers in 2009 are much the same as for nitrogen and phosphorus. Volatility of potassium pricing is likely to be more severe — as was seen in the summer of 2008 than for nitrogen and phosphorus.

Some of the drivers of worldwide potassium supply and price include:

World population, which has risen in the past 40 years from less than four billion people to more than six billion. Subsequently demand for grain increased during that time frame by over a billion tons.

Perhaps the most significant of world consumption factor that drive all fertilizer availability and cost is the dramatic jump in meat consumption over the past 40 years, from 80 million tons in 1967 to nearly 300 million tons in 2007.

Grain production, including wheat and coarse grains, on a worldwide basis reached a record level of nearly 1.8 billion tons in 2008. Despite the record growth in production, world supplies of most grains are near record lows.

Yield worldwide on grain crops, including corn, soybeans and rice remains inequitable, with the U.S. producing an average corn yield in 2008 of more than twice the nearest competitor (China). Rice is similar, though China has closed the yield gap significantly in recent years. Only in soybeans is average yield comparable in the U.S., China, India and Brazil.

Worldwide, 14 percent of the potassium used on crops is used on corn, compared to 13 percent for rice and eight each for soybeans and wheat. On a global basis palm oil and sugar each use almost as much as wheat and soybeans.

China uses the most potassium (20 percent of the world supply), followed by the U.S. 17 percent and Brazil 14 percent. India currently uses only 8 percent of the world's supply of potassium, but ranks among the top three countries in the world in grain acreage.

In the U.S. 46 percent of the potassium used goes on corn. By comparison, in Indonesia and Malaysia over 70 percent goes into palm oil production and in China nearly 50 percent goes into fruit and vegetable production.

Potassium usage worldwide topped out at just under 55 million tons in 2007 and dropped to 53 million tons in 2008. In the past 10 years potassium usage has been up and down, but the trend is clearly toward an increase use of K worldwide.

In 2009, there are two different, but similar, scenarios being forecast for potassium use, says Jeff Holzman, manager for market research for Potash Corporation.

“Under one scenario, we are predicting level usage in 2009 — at about 53 million tons. If world financial conditions are more favorable, the other scenario calls for a slight increase, possibly up to the record usage of 2007,” he says.

As of November 2008, U.S. inventories of potash were 37 percent below the five-year average. Inventories dropped from a high of just over three million tons in February of 2008 to just over one million tons in November of 2008.

As double-crop soybean and wheat growers in the Southeast can attest, prices for potassium have been volatile in the past couple of years. In the spring of 2007, prices averaged around $200 per ton. At the same time in 2008, prices topped $600 per ton, and sometimes was not available at that price.

New production projects worldwide are expected to boost production adequately to take care of increased demand worldwide in the long-term. In the short-term, demand for 2009 is expected to be at or above 55 million tons — close to production capacity,

Holzman was asked at a recent meeting to give growers a projection on what a ton of potash might cost in 2009. His reply: “Too many factors to even give you a guess.”