Crop rotation can keep pesticide costs down

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Soybeans are Manitoba's third crop, with 875,000 acres planted in 2012. (AP ARCHIVES)

Move over canola. Manitoba has a new wonder crop. Some are even calling it the new Cinderella on the province's farmscape.

Soybeans officially snuck into third place behind canola and wheat as the crop seeded to the most acres in the province last summer. While at 875,000 acres, it has a long way to go before it catches up to canola at 3.5 million acres or wheat at 2.9 million acres, it is really starting to turn some heads.

Many pundits are predicting soybean acres will surge again next spring to crack the one-million-acre mark, largely at the expense of canola and edible-bean acres grown in the province.

The reasons are many, but they start with the numbers. Canola has long been touted as the crop that brings in the most cash on Manitoba farms, but once the costs of growing the crop are factored in, it isn't necessarily generating the best profits.

A comparison of variable production costs produced by NorthStar Genetics shows it costs a farmer about $114 to grow an acre of soybeans compared to $179 for canola. The gross revenue for soybeans is slightly lower, $482 per acre versus $498 for canola. But the net revenue is $50 per acre higher at $368 per acre, largely due to the fact canola is a huge consumer of nitrogen fertilizer, while soybeans are a legume that produce their own.

Besides all that, canola is looking a bit tired these days. Its yield on many Manitoba farms has been trending down, and in fact, took a big dip this year, partly due to weather, but largely due to growing it more often than the recommended one year in four on the same field. That's an open invitation to pests and diseases that overwhelm the crop's built-in genetic resistance, so farmers have to compensate with expensive fungicides and insecticides.

As a relative newcomer to the Manitoba scene, soybeans have shown themselves capable of performing well in wet conditions and equally well when it's dry.

Soybeans don't like the cold, but as the soybean and corn belt of the Northern Great Plains continues to edge northward, plant breeders have been developing better short-season varieties. As well, Manitoba has had warmer-than-usual summers in recent times. Heat units across much of agro-Manitoba this past summer, for example, were between five and 15 per cent above the historical average.

A recent Business Week online article quoted one farmland investment firm as characterizing Canadian farmland as a "long-term investment play on global warming," one of the factors driving farmland values nationwide up 27 per cent between 2007 and 2011.

As with many new love affairs, farmers and soybeans have enjoyed a honeymoon free of pests as the crop has settled in over the past decade or so. There's a growing concern producers have been lulled into a false sense of security and are practising the same lazy rotations that got them into trouble with canola.

Extension agronomists are warning the honeymoon is over. There's evidence the pests are tracking the crop northward.

"When you have a new crop, you don't have all the pests and diseases around, but they build up over time," Hans Kandel, a researcher from North Dakota State University, told the Manitoba Agronomists Conference this past week.

Yield robbers such as root rots and soybean cyst nematode, a parasitic worm, have surfaced in North Dakota, affecting yields and forcing farmers to take corrective action.

The cyst nematode was once only associated with soybean crops grown in the far U.S. South. It was first noticed on the North Dakota and South Dakota border in 2003. In 2011, it was found in a county just south of the Canadian border.

"Do you have it?" Kandel asked. "I can't guarantee you have it, but I can't guarantee you don't have it, either."

But he does know one thing.

"Once you've got it, you have it," he said. The parasite, which feeds on the roots, often cuts into yields long before farmers realize what's going on, because its damage causes symptoms often attributed to other factors. The only way to identify its presence is through a soil test.

Once it becomes established, farmers are limited to growing resistant varieties or sowing the field to other crops until the parasite numbers drop to levels where they can reintroduce soybeans to the field.

Kandel says the best insurance against giving the pests a leg up is to adhere to a diverse rotation. That means looking beyond the numbers when deciding which crops to plant each season.

Laura Rance is editor of the Manitoba Co-operator. She can be reached at 204-792-4382 or by email: laura@fbcpublishing.com

Republished from the Winnipeg Free Press print edition December 15, 2012 B7