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Potash on the Prairies

Nitrogen (N), phosphorous (P), potassium (K) and sulphur (S): the four major nutrients that keep us going in Western Canada.

The abbreviation “K” for comes from “Kalium” — German for potassium. The first major K mine began at Stassfurt, Germany in 1861. By 1900 Germany was producing more than a million tons of potassium for agricultural purposes.

The word “potash” actually comes from the original agricultural source of K fertilizer — putting burnt wood or other “ash” in a “pot” and washing the salts out with water. Early on, it was learned that the K was the valuable part of the ashes rather than the other salts.

In fertilizer talk, “potash” refers to K2O, which is just a method of expressing the K content that harks back to early chemistry days when soil analysis for plant nutrients was expressed as the oxide so it would all add up to 100 per cent. There is no K20 in potash fertilizer — the compound is KCl (potassium chloride).

When the federal government pushed the metric system down our throats in the 1970s, I tried mightily to get the fertilizer industry to throw out P2O5 and K2O and move to P and K. Not so easy — the fertilizer industry is international.

Potash

In Saskatchewan, potash is a very large-P political animal. A very important chunk of our provincial revenue comes from our potash mines.

While Saskatchewan sits on one of the best K deposits in the world, most Saskatchewan and Western Canada farmers can get along quite nicely without using it. A 50 bushel wheat crop may have 80 pounds or more of K20 above the ground, but most of it is in the straw and is returned to the soil, so we haul off little.

Many years ago I was giving a talk to agronomists in Alberta and I said, “In Alberta, use all the K you want on any soil you want in any amount you want — we have all that good potash under Saskatchewan and we’ll gladly sell it to you.”

Having said that, there are places in Saskatchewan (and Manitoba) with some of the most K-deficient soils in the world. They are the Carrot River soils of northeast Saskatchewan and the Almassippi soils of central Manitoba.

In the 1960s, 70s and 80s we did dozens and dozens of experiments all over Saskatchewan. In Carrot River we learned that farmers should either apply K or quit farming. In most other areas there might be the odd response of a bushel or three but it is no big deal. When K2O could be bought for $0.10 per pound, adding a few pounds wasn’t significant, but at $0.50 a pound for K2O, it’s a different story. I’ll spend my fertilizer dollars on N and P.

Potash deficiency

As early as 1871 in jolly old England they had discovered where the need for potash lay “On light sandy soils and peat soils” (from A History of Agricultural Science in Great Britain, 1620-1954, by E.J. Russell).

As the years go by and we grow ever larger crops we are “mining “ our soils for K so a constant watch must be kept — but there are still many of us who can survive very well without the K we dig out of the ground

When our K work at U of S was in the heydays of the 1970s, I wrote up a proposal calling for the potash industry and the Saskatchewan government to establish a potash demonstration farm at Carrot River. They are some of the most K deficient soils in the world and we could work out all the details for using it: placement, rates, soil building, safe rates withseed andso on. Then, we could bring Chinese and other customers to see the experiments in action.

But alas, Carrot River was too far from the Saskatoon airport. †

About the author

Columnist

Les Henry

J.L.(Les) Henry is a former professor and extension specialist at the University of Saskatchewan. He farms at Dundurn, Sask. He recently finished a second printing of “Henry’s Handbook of Soil and Water,” a book that mixes the basics and practical aspects of soil, fertilizer and farming. Les will cover the shipping and GST for “Grainews” readers. Simply send a cheque for $50 to Henry Perspectives, 143 Tucker Cres., Saskatoon, Sask., S7H 3H7, and he will dispatch a signed book.

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