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Copper: For peat’s sake!

Think peaty soil isn’t worth farming? Just add copper to get better results

Peat is nature’s natural organic compost. As a field crop amendment, peat has a lower carbon-to-nitrogen ratio (C:N), 60:1, than straw or cattle manure — that’s around 80:1. Canada has 270 million — yes, million — acres of peat lands, making up 25 per cent of the world’s peatland supply. Peat is harvested right across Canada at just over 1.5 million tons annually. This peat production is around one per cent of world production.

Peat is harvested in Canada at less than 60 times the rate in which peat accumulates annually — wouldn’t you call this sustainable production? Presently one acre of peat is being harvested for every 6,000 acres. The general public refers to peat harvesting as mining — a very odd term since peat harvesting merely removes two to three inches of dried peat from the peat bog surface annually. This process continues for up to 50 years until several feet of peat are removed. The peat is piled and bagged with 90 per cent primarily exported to the U.S.

After harvesting a few feet or so, peat bogs are allowed to reflood and the process of peat buildup resumes. Most harvested peat is the brown acidic sphagnum type with a pH of three to four. The annual industry value of peat in Canada is around $320 million, most of which is exported as backhaul to the U.S. and Mexico in the trucks that bring fruits and vegetables to the Prairies. On the Canadian Prairies, peat harvesting is worth some $62 million annually in Manitoba and some $53 million in Alberta. Very little peat is harvested in Saskatchewan.

Peat bogs or peat lands in all three Prairie provinces are for the most part acidic with levels around a pH of three to four. Such peat can hold up to 20 times its weight in water. To a lesser degree, there are hundreds of thousands of acres of peatlands that range in pH from five to seven and higher. These nutrient-rich peats have, over time, been infiltrated with dissolved limestone (calcium and magnesium carbonate) thus raising the pH. Such peat soils are generally black in colour and are referred to as muck soils from Florida to Alaska. In the U.K., these soils are called Fenlands and, as in North America, very highly productive.

The muck soils that I am most familiar with are the Holland marsh area of Ontario (north of Toronto) and the tens of thousands of black muck soils north of Edmonton in the Barrhead/Westlock area of Alberta.

Acidic peat on croplands

Acidic peat has many impacts on croplands:

  • Helps water and air exchange;
  • Helps root growth and nutrient exchange;
  • Provides buffering for the soil;
  • Retains moisture in dry or sandy soils;
  • Reduces fertilizer leaching;
  • Keeps soil from hardening and crusting;
  • Aerates heavy soils and binds dry soils; and,
  • Provides some nutrients.

Acidic peat is easily worked into cropland soils. If many tons of peat are applied to cropland it should be disced in ASAP. Remember, peat has a C:N ratio of around 60, wheat straw around 80. Nutrients, especially sulphur and nitrogen, should be incorporated over and above the needs of the following crop just as you would have done for wheat straw. The nitrogen, phosphorus and potassium levels in acidic brown peat are very similar to cow manure. The incorporated peat will release these nutrients over the next two to three years.

Farming Peatlands

I was first aware of Alberta’s muck soils (peatlands with a pH of six to seven) in the Westlock/Barrhead region just north of Edmonton in the late 1970’s. I was told that cereal crops in particular would grow poorly or not at all on these black peaty soils, especially wheat and barley. The story went that these soils were too wet, too cold and too frost prone for cereals. These tens of thousands of peat acres were considered marginal and not worth farming. None-the-less, muck peatlands reminded me of Holland Marsh in Ontario, the muck soils of Florida and the Fenlands of the UK which were considered to be highly valuable croplands.

My answer came from Jerry Stoller, founder of Stoller USA. Jerry suggested that I apply generous amounts of copper sulphate to a small plot of land in any field seeded to wheat or barley in 1981. He recommended a rate of 10 pounds of actual copper (40 pounds of copper sulphate) per acre. In small plot terms that is one ounce of copper sulphate to 70 square feet. The results in early July of 1981 on a barley field: a vigorous plot of barley surrounded by a field of dead or dying barley plants.

Despite the dramatic results from copper application the skeptics, naysayers and luddites were numerous. It took another 10 to 20 years to realize the effect of copper application on these very fertile peatlands.

In the late 1980’s Ray Dowbenko, an agronomy student at the University of Manitoba, did his master’s thesis on the copper fertilizer requirements of Peat Soils.

Ray’s results were dramatic. He found that adding 4.5 pounds per acre and nine pounds per acre of actual copper increased barley yields on Manitoba peatlands with increased yields out of this world, just copper increasing yields from three bushels to 83 bushels of barley. Your wildest dream!

All five locations in Manitoba gave huge yield increases as seen in the table above. None-the-less, there are still those individuals who cannot come to terms with copper requirements of small grain cereals, especially on peat and sandy and high organic soils.

In the case of peat soils, the copper is low to begin with and what is present becomes sequestered by the organic matter so as to be unavailable to plant growth. In order to overcome this problem it is recommended that 10 actual pounds (10 kg/ha) of copper be applied to peatlands, that is 40 pounds of bluestone per acre. This level of copper is good for perhaps eight to 10 years but the returns on wheat and barley yields as well as the quality pay for the copper application in just one year.

Wheat, flax and canary seed and barley are the most copper sensitive, followed by alfalfa, timothy and oats. Peas, canola and rye are relatively insensitive.

If you farm or own any kind of peatland, just do it. A few handfuls of bluestone on such land will convince you and silence the many naysayers once and for all.

About the author

Contributor

Dr. Ieuan Evans is a forensic plant pathologist based in Edmonton, Alta. He can be reached at [email protected]

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