Soil Testing Staves Off Problems

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Liebig’s “Law of the Minimum” principle was developed in the 19th century by German agricultural scientist Justus von Liebig; the thesis is that if one essential plant nutrient is deficient, plant health and growth will be poor, even if all other nutrients are present and abundant.

Phosphate Fireworks

Of all the fertilizer inputs, none has gone up faster and higher than phosphorus.
The world is in a feeding frenzy that would shame a shark, and it’s questionable whether there will be enough to meet world demand. “I don’t know where we will find enough phosphate to feed crops around the world,” says CHS Crop Nutrient Sales Manager Frank Edwards. “We are buying heavy; other countries are buying heavy. Phosphate prices are double or triple from where they were last year.”
The supply of triple superphosphate (0-46-0) is almost nonexistent, so growers are having to turn to DAP (18-46-0) and MAP (11-52-0). Retail prices for DAP have gone up nearly $300 per ton in the last year.
If there’s a bright spot, DAP and MAP both contain nitrogen, so some of the high cost of the phosphate in both is somewhat offset.

In other words, growth is controlled not by the total nutrients available, but by the scarcest. Liebig used a wooden barrel to explain his law: The capacity of the barrel is limited by the shortest stave.

Liebig’s Law applies particularly to nutrient management in cotton, and a simple example is this: You can use 200 pounds of nitrogen per acre, if you choose, but if your soils are deficient in phosphorus or potash, or even essential micronutrients, your cotton crop cannot reach its full potential.

“Rule number one is to always make a fertilizer decision based on a soil test for phosphorus and potash,” says Dr. Larry Oldham, Extension soil specialist at Mississippi State University.

But soil sampling across the Cotton Belt is sort of like flossing. You want to do it. You mean to do it. And probably you tell your dentist you do it. But do you?

Soils constantly undergo physiological changes. Plant uptake, leaching, volatility and erosion can all remove nutrients from the soil. That’s why soil testing is so valuable. Measuring available nutrients in the soil serves as the best guide to profitable use of fertilizers.

With fertilizer prices being what they are, it’s also essential that you put out exactly what you need, when you need it. “Make sure equipment is in good shape and calibrated,” continues Oldham. “You want to be sure you are putting out what you think you are putting out. Put it where it is supposed to go and when it is supposed to be there.”

And face reality: “Be realistic,” he says. “Know what your production potential is, considering the soil type and irrigation.”


The Price Of Potash Is Looney

In the 2006 Winter Olympics in Turin, Italy, for good luck the Canadian hockey team managed to slip a Canadian dollar — known as a “Looney” — onto the ice rink before water was added and frozen. A Canadian dollar has on its face an image of a common loon, a well-known Canadian bird. (Just so you’ll know, the flip side also has an image — Queen Elizabeth II.)
One American official joked that the U.S. team would have matched the Canadian dollar if we’d had a 56-cent piece. At that time, a Canadian dollar was worth only 56 cents American.
But the jokes backfired on both the Canadians and the Americans. What was supposed to be one of the all-time best Canadian teams didn’t even make it to the bronze-medal round. And now an American dollar is worth almost exactly what a Canadian dollar is.
How that comes to apply to potash is relatively simple. The United States imports 90% of its potash — and Canada produces almost all of that. For example, in 2002, one American dollar would buy $1.56 in Canadian potash. Today the ratio is 1:1. One American dollar buys one Canadian dollar worth of potash.
At the moment, potash is so short it is under allocation in the U.S.

Oldham says much higher fertilizer prices also make it essential that growers establish and cultivate relationships with fertilizer retailers. “The increases in prices are not just happening at the retail level – it’s happening all up and down the supply chain,” he says.

“A company has to make a healthy investment to buy a barge load of fertilizer. Sellers have to make sure they have the fertilizer marketed properly,” he continues. “They can’t have their capital tied up in fertilizer sitting in a warehouse. Growers need to understand that a dealer has to look at his business, too.”

Oldham writes in his “Nutrient and Soil Management” newsletter that fertilizer price volatility didn’t just happen over night. Factors he pointed to were:

  • Disruptions in manufacturing and shipping caused by Hurricanes Katrina and Rita in 2005.
  • Higher energy prices.
  • Depressed global grain stocks have increased grain prices around the world, which has increased demand for crop nutrients.
  • The declining value of the American dollar. Imports cost more.
  • Transportation costs have increased all along the supply chain.
  • Economic conditions in Brazil, India and China have increased the demand for meat protein, which increases fertilizer-based crop production to produce meat.

All Nitrogen Is Considered Equal

All nitrogen sources are considered equal in the ability to provide nitrogen to cotton. No one form or source is superior to another if all are applied correctly, according to data from Mississippi State University.
Forms of nitrogen vary. In the Mississippi Delta, for instance, 32% solution and urea are the forms of choice, while in North Carolina, it might come in the form of something as simple as chicken litter.
“If you are close enough to get it, chicken litter is a good source of nitrogen,” says North Carolina Extension Cotton Specialist Dr. Keith Edmisten. Not to mention that most chicken litter is free. It’s a case of mutualism: Growers need the nutrients in the litter; chicken and turkey producers need it hauled off and disposed of in an environmentally friendly manner.
Most blanket recommendations for nitrogen in cotton call for from as much as 110 pounds in the Mississippi Delta to as little as 60 pounds in North Carolina.
The recommendations generally call for split applications based on yield potential and soil type. Timing of applications is just as essential. Applications can start at preplant and extend to first bloom. In some instances, foliar applications are effective.

Demand Driven
The logistics of supplying nitrogen fertilizer changed in 2007 when 93 million acres of corn were planted. Because of that, the supply of all forms of nitrogen all but disappeared. The industry as a whole has recovered nicely, and there appears to be enough nitrogen in inventory to feed a huge wheat crop in the Cotton Belt and get a cotton crop started.
But with increased demand, a weak dollar and the loss of the U.S. nitrogen-producing infrastructure (as much as 50% of the U.S. nitrogen is imported now), nitrogen prices have not backed off.
Anhydrous ammonia is the main feed ingredient in all inorganic nitrogen fertilizer products, and one of its main building blocks is natural gas. Despite the fact that natural gas prices have dropped nearly 30% over the past three years, demand is keeping the price of nitrogen fertilizer at record prices.

Captions (3):
Phosphorus deficiency.
Potassium deficiency.
Nitrogen deficiency.

Add Charts (4):
Average Farmer Prices for DAP
Average Farmer Prices for Potash
Decrease in Buying Power
Average Farmer Prices

Gantz is the editor of Cotton Grower magazine. Over the years, he has won many National Agricultural Marketing Association awards, including two national NAMAs – one in advertising and one in public relations. Gantz brings hands-on experience, having worked as Sales Manager for an agricultural supply distributor in the Mississippi Delta.

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