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Myths, yarns and ridiculous claims

Many long-standing popular myths about agriculture have been disclaimed by science

After 60 years of work and observations in Canadian, British and U.S. agriculture, most of it on the Canadian prairies, I still cannot believe how many farmers and scientists believe in plain falsehoods. Here are a few of those unsubstantiated myths.

Manure causes lodging

FALSE: If you apply 10 to 20 or more tons of cattle manure per acre to cropland, especially sandy soil and then plant wheat the crop will lodge due to excess nitrogen.

Diagnosis: Yes, the wheat will often lodge, especially on sandy soil, but this is primarily due to a lack of copper and nitrogen starvation. When you apply cattle manure with an 80 to one carbon to nitrogen ratio at 20 tons per acre, you’re applying a huge amount of carbon for the soil bacteria and fungi. With this huge bonanza of food, the bacteria and fungi quickly multiply and tie upsoil nutrients.

Most often in sandy soil the limiting nutrients are nitrogen and copper. The bacteria and fungi grab these nutrients before the wheat crop has a chance. Consequently, you have weak, nitrogen-starved wheat and no copper for stem lignin synthesis. Without lignin, wheat stems are like flexible rope, and the spindly, lodged wheat plants have very poor grain filling due to nitrogen starvation.

Correction: You need to apply about 100 pounds per acre of extra nitrogen to compensate for the nitrogen tie-up by the soil microflora, and a foliar application of copper at the shot blade stage just before head emergence. If your soil had been tested and was low or deficient in copper, you could have applied about 15 to 20 lbs. of bluestone per acre (four to five pounds of actual copper). You would then be guaranteed your 60 bushels of wheat (or your target yield) provided there was no other nutrient deficiency. In succeeding years, the bacteria and fungi die off and release the macro and micronutrients they tied up following the carbohydrate (carbon) manure bonanza.

Burning increases yield

FALSE: After you burn straw in a cereal field you get an increased yield due to disease control.

Diagnosis: There is a lot less straw burning now than in the past but it does still take place. What really happens is the carbon in the straw goes up in flames, along with about 30 pounds of nitrogen and seven pounds of sulphur from a 60-bushel crop of wheat straw or an 80-bushel crop of barley straw. In addition, there is no tie-up of the soil nitrogen by the two-or-so tons of straw. If left in place and worked under in the spring, the straw would release an additional 50 pounds of nitrogen as well as a few pounds of soil sulphur in the rotting and decomposition process. There might be some disease control with burning, but foliar disease outbreaks are more dependent on weather in any given year.

Correction: On a quarter section, the loss from burning the remains of a 60 bu./ac. wheat crop, amounts to 4,500 pounds of nitrogen and 1,000 pounds of sulphur. You just degraded your cropland and sent thousands of dollars up in smoke.

Cereals are shallow rooted

FALSE: Cereal roots stick to the soil surface and do not move into the subsoil, canola goes down a foot or so and only alfalfa grows deep into the subsoil.

Diagnosis: In wet years, cereal roots may be confined to the top six to eight inches of soil. If it’s very wet, canola and alfalfa roots will rot and yields will plummet. Soybeans are the only member of the legume family that can cope with wet soils and even they struggle. In water-logged soils, roots cannot get oxygen and they die.

Correction: Water moves from wetter areas to drier areas, so if the soil profile is 10 feet deep and there is moisture at the 10-foot level, this moisture (vapour) will move upwards as the top soil becomes drier. As the soil dries out, the ability of the soil to move water upward to the soil surface limits the evaporation rate. Plant roots actually take in water films from the soil particles very efficiently and they need oxygen (air) to function effectively. A good wheat crop can drain the soil profile down to 10 feet or more, even if the cereal roots go no deeper than three feet or less.

Alfalfa can grow anywhere

FALSE: Alfalfa will grow in any well-drained soils.

Diagnosis: Research has shown that if you seed alfalfa in soils with a pH as low as 5.0, they will actually grow fairly well as long as the soil drainage is good. But if the pH is below 6.5 the bacterial rhizobia necessary to form the nitrogen-fixing root nodules just die out. In other words, the alfalfa cannot fix nitrogen so you may as well plant brome grass. Alfalfa needs a pH between 6.5 and 8.5 to fully and effectively fix nitrogen to outcompete weeds and grasses. A good field of alfalfa at proper pH can actually fix around 200 pounds of nitrogen annually.

Correction: If your soil pH is around 5.5 you will need several tons of crushed limestone (actual amounts depend on soil type) to bring the pH close to 7.0 to allow the alfalfa to effectively reform its miracle of nitrogen fixation. In Prince Edward Island, the natural pH is around 4.0 – 4.5 so even to grow potatoes they have to crush and import lots of Nova Scotia limestone.

Alberta has no rats

FALSE: Alberta has no Norway rats.

Diagnosis: Most of the time we do not, but the provincial government has to maintain vigilance to eradicate new and regular infestations that arrive from Saskatchewan, Montana and in trains or trucks. No infestations come from British Columbia or the territories. No, they do not humanely catch the rats and release them back into Saskatchewan — they terminate them as quickly as possible.

Norway or common rats are very destructive on farms and urban areas. They damage grain, stored foods, buildings and electrical installations as well as carrying fleas and human infectious diseases. In rat-infested areas of the eastern Prairies, rat urine and feces contaminate the very food grains that we eat.

Correction: Alberta’s primary rat control program, began in the 1950s when rat infestations were in the hundreds. Infestations dropped off in the 1980s, and now only occasional infestations are found. Pest control officers primarily patrol the Saskatchewan border areas but they will look for and exterminate rats found anywhere in the province.

The rat control program costs less than half a million dollars annually but the overall savings in structural damage and spoiled and contaminated foods saves very many millions of dollars annually. Why other provinces have not followed suit is a bureaucratic mystery.

Seed by the calendar

FALSE: Producers should seed according to the calendar.

Diagnosis: You often hear statements like “I always seed my wheat by the first week in May.” A couple of seasons back, temperatures over most of the Prairies were in the high 20s by the end of March. Farmers were playing a waiting game and many did not seed even wheat or peas until a month or so later. By early May, fields in the Edmonton area were bone dry and wheat and canola seeded in early May did not get enough surface moisture to germinate until June. Farmers that seeded wheat, peas and barley during the first week in April — when soil temperatures were above 5 C at the two-inch level and the soil was moist — found their crops were headed out by late June and caught the July rains. Yields were high and quality was good. The seed-by-calendar growers were harvesting mediocre crops in late October, hoping the snow would hold off.

Correction: Why wait for the calendar when conditions are right?

Disease is inevitable

FALSE: Diseases such as sudden death syndrome of soybeans, soybean cyst nematode and cereal cyst nematode are inevitable in Western Canada.

Diagnosis: Unlike taxes and death, few diseases or pests are inevitable. Diseases such as sudden death syndrome, soybean cyst nematode and cereal cyst nematode can only move into a field if they are brought in with mud on farm equipment, oilfield equipment, pipelines or powerlines. Quit listening to the prophets of doom, set up your own sanitation system. An ounce of prevention is worth a ton of expensive control.

Correction: Golden and pale cyst nematodes are a devastating disease (yes, nematode infections are called diseases) of potato crops. These diseases occur in both Newfoundland and Vancouver Island and have been there since the 1960s. Federal and provincial governments’ cooperation has kept these pests out of Canada’s major potato-growing areas. In Alberta, control programs for fusarium, blackleg of canola and bacterial ring rot of potatoes have saved producers not millions but billions of dollars over the years.

The same can be said about aphanomyces rot of peas and lentils and clubroot of canola: run your own on-farm preventative program. Restrict or prevent vehicle equipment on your farm and in the case of canola, plant resistant varieties as soon as possible.

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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