In 1981, I heard a discussion on micronutrients in crop production by the late Jerry Stoller. He talked about the need to pay attention to the micronutrient needs of crops, because just like macronutrients — nitrogen, phosphorus, potassium and sulphur — they can be depleted over time on even the best cropland.
Stoller also said peat soils in Alberta, particularly neutral-pH soils prevalent in the Westlock and Barrhead regions, could be farmed if we applied micronutrients, copper in particular.
Following his initiative, an Alberta Agriculture district agriculturalist applied a few ounces of copper sulphate to a fixed footage of a barley crop sown on a flat, fairly dry section of neutral pH peatland. The results in 1981 were dramatic.
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I took a photograph that can be seen on page 3 of the fact sheet “Copper deficiency: diagnosis and correction” (Alberta Agriculture, Agdex 532 – 3). Later work on copper nutrition in cereal crops, particularly wheat, was then done on peat soils and sandy/loam soils at Lacombe by Lu Peining and at Edmonton by Alberta Agriculture’s crop protection group. We all got amazing results with copper fertility, particularly on wheat and barley, and we also had to cope with mountains of skepticism, primarily from soil scientists.
Peatlands in Canada cover 12 to 13 per cent of the country’s total land area. This amounts to some 320 million acres. Much of this acreage is wet, shallow or acidic and it accumulates annually at some 60 times the rate that it’s harvested for compost. Despite this, many in the general public seem to think it is a limited resource.
Of those 320 million acres, only about one million are used for agriculture in Prairie Canada and less than a million for grassland. Elsewhere in North America, these black agricultural peat soils are referred to as fenlands, such as the 200,000 acres in Florida’s Everglades and the black peatlands of Ontario’s Bradford (Holland) Marsh.
On the Bradford Marsh, some 7,000 acres are used for horticultural crops — and believe it or not, on page 35 of Ontario’s Agronomy Guide for Field Crops, it states that when these organic soils are brought into production, they must be treated with 12.5 pounds per acre of copper per year for three years.
That means 50 lbs. of bluestone per acre for three years, which is 25 per cent copper. Copper is 25 per cent by weight of copper sulphate. About 230,000 acres of peat soils are cultivated in the Everglades for horticultural crops and sugarcane. These peat or fenland soils are heavily fertilized with copper sulphate on a regular basis.
Here in these tables we see the factual data from a Manitoba Agriculture fact sheet published in March 1990 and written as part of a master’s degree by Ray Dowbenko. It was provided to the Manitoba Peat Growers Association but otherwise hardly saw the light of day.
Across Western Canada there seemed to be a consensus among soil scientists that micronutrient requirements in field crops were fictional. Dowbenko listed wheat, flax and canary seed as the most sensitive field crops to copper deficiency, barley and alfalfa as medium-high, oats and corn as medium and peas, clovers, canola, rye and forage grasses as low.
He found that producers who burned their peat fields in the past could grow good cereal crops. That practice is now forbidden in our Prairie-wide dry cycle. In fact, in Alberta there are dozens of smouldering peat bogs that inevitably fire up in windy dry summers — forest fires in the waiting. That’s a good reason to harvest dry peat bogs.
When Dowbenko did his research in the 1980s, there were three copper fertilizer products available: copper sulphate; EDTA copper chelate; and sequestered copper chelate. Today there are far more copper-based products. Both chelates are liquids and, when mixed with water, can be applied with a herbicide sprayer.
Copper sulphate is somewhat corrosive and should only be applied with a Valmar spreader or similar equipment and incorporated after broadcast. Rates of 10 kg/ha (nine pounds per acre) of actual copper (copper sulphate is 25 per cent copper by weight), translates to 40 kg/ha or 36 lb./ac. of copper sulphate and may be effective for six to eight years.
Table 1 above is taken directly from the Manitoba fact sheet. Note the huge yield differences. Even with the high price of copper, do the math and figure out your cereal yields over eight years.
Table 2 shows the effect of the three kinds of copper, taken as a mean of two barley sites. The foliar application was the least effective at 27 and 39 bushels of barley with either EDTA chelate or sequestered chelate. Soil incorporation was by far the best of all three products.
Table 3 gives the 1989 prices of copper so you will have to substitute those with 2024 prices. Both barley and wheat have risen considerably in price as well.
In 2010, I persuaded a Swan River farmer to apply 25 lbs. of bluestone to a quarter section, at a cost of about $150 an acre. This quarter usually produced around 40 bu./ac. of sample wheat. Following the fall copper application on this 10 per cent organic soil, there was a 70-bushel yield of No. 2 wheat. The cost of the copper application was covered by the increased wheat yield in one season. I estimated the copper application on this quarter was good for at least 10 years.
The original fact sheet is unavailable, but a few years ago I obtained an original copy from Dowbenko. I have since given away hundreds of copies.
