Preventing And Correcting Soil Erosion

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Vegetation protects soil from wind erosion by reducing the wind speed at the soil surface,” says Dr. Ross McKenzie, research scientist with Alberta Agriculture and Rural Development, Lethbridge. “Vegetative cover, such as a growing crop, standing stubble or crop residues are very effective in helping moderate the potential of wind erosion. The elimination of cultivation and using direct seeding are the best ways to maintain crop residue on the soil surface.” Wind erosion was a frequent problem across the drier regions of southern Alberta, but with the adoption of conservation tillage and direct seeding, wind erosion is no longer a frequent occurrence in southern Alberta on dryland fields. However, in irrigated areas, cultivation is still frequently used and on lands used for row crop production, particularly for sugar beets, potatoes and beans, great care is needed to keep wind erosion in check.

“If soil erosion occurs, there are some practices that can be done on a temporary basis,” says McKenzie. “For instance, producers may need to consider using emergency tillage to break up the smooth surface of a bare field into a rough, cloddy surface. A very rough soil surface can reduce the wind velocity at the surface and provide traps to catch windblown soil particles. Producers who have problem fields may need to consider working perpendicular to the prevailing wind direction to obtain maximum effect.

Continued field observation and care are needed as this type of emergency tillage is only a temporary protection measure, because when soil clods are broken down by the wind, the field becomes smooth and susceptible to wind erosion once again.”

Prevention measures

To minimize wind erosion on fields grown to row crops or root crops that are harvested:

leave as much residue on the soil surface as possible

leave the soil as rough and ridged as possible

spread straw and manure onto areas most prone to erosion

seed to cover crop as soon as possible after harvest (after bean or potato harvest) to crops such as barley, fall rye, winter wheat or another winter cereal.

“Reclaiming eroded soils is a very long, slow process,” says McKenzie. “The first thing that needs to be done is soil sampling to determine nutrient and organic matter levels. If there is subsoil exposed, it may be necessary to do some deep tillage with a para-plow and go down up to 20 inches and actually reduce the bulk density by fracturing and loosening the soil. Doing this deep tillage in the fall when the soils are dry, will help to ensure good fracture and breakup of the soil. Then going in with a very good application of manure and putting on a very good application (30 to 50 tons per acre of feedlot manure) would go a long way to improve the physical condition of the soil and the nutrient level of the soil. While that amount of manure may sound like a lot, most eroded soils are very deficient in nutrients and the manure will help to improve the physical quality of the soil.

A federal task force has been criticized for not asking Ottawa to close a legal loophole allowing livestock producers to import unapproved veterinary drugs virtually unrestricted.

Instead, the task force calls for a three-year pilot project into the feasibility of limiting such imports while not cutting them off completely.

Health Canada formed the task force in December 2006 to examine ways of restricting own-use importation (OUI) of animal drugs. The task force tabled a report in August 2008 but it did not appear on the department’s website until recently.

The Canadian Medical Association Journal in a recent article hinted livestock and industry organizations on the task force swayed the group against coming down harder against OUI.

Canadian farmers legally import an estimated $100 million worth of animal drugs annually under OUI. Some, including antibiotics and antimicrobials, are not actually approved for use in this country.

Medicated feed may be given to livestock in Canada without prescription as long as it is mixed according to federal standards.

The CMAJ noted the task force failed to reach consensus on some key issues, such as which drugs to exclude from OUI. It pointed out the task force contained no public health experts but did have representatives from beef, pork, dairy and pharmaceutical industry associations.

“The own-use task force’s recommendation to delay regulation of such own-use importation galls both public health experts and even some of its own members,” the article said.

It cited one task force member as mainly blaming the Canadian Cattlemen’s Association for the lack of consensus.

Rob McNabb, CCA general manager and its alternate member on the task force, said his group is only looking for compromise on restricting imports while still allowing some in.

“Our desire through the task force was ‘let’s narrow that down.’ We don’t want stuff that’s produced in a bathtub in China or Bangladesh or wherever. But we feel we have a legitimate case that products licensed and manufactured in the U. S. be allowed under permit to continue, under a much more restricted regime, to be imported for producers’ own use,” said McNabb.

CLOSE LOOPHOLE

However, a leading swine veterinarian in Ontario disagrees.

“I don’t think there’s any way around this one,” said Dr. Catherine Dewey, department of population medicine chair at the Ontario Veterinary College in Guelph. “We have to close (the loophole) because it’s a way animals are being medicated without proper veterinary supervision.”

Own-use importation of farm chemicals, including veterinary drugs, is a hot button issue with many farmers.

Producers say they need the option of importing cheaper products to cut operating costs and remain competitive. They also say they wouldn’t have to do so if the system in Canada weren’t so slow and cumbersome in registering new products.

A resolution passed at the Keystone Agricultural Producers annual meeting in January called for the OUI program to continue. The Canadian Federation of Agriculture adopted a similar resolution at its own annual meeting in February.

But a previous Health Canada advisory committee report in 2002 called on Ottawa to plug the own-use loophole because “(t) here can be no assurance… that products used under these circumstances are safe.” It recommended stopping “the importation, sale and use of antimicrobials not evaluated and registered by Health Canada.”

UNREGULATED

One of the main concerns about the unregulated use of antimicrobials is the risk of developing antibiotic resistance in animals.

Antimicrobials are often included in starter rations for pigs as a matter of course, both to guard against illness and also to promote growth. The drugs are also used to a lesser extent in grower and finisher rations.

Dewey said it’s possible for nursery pigs to be exposed to as many as six different antimicrobials in the first few weeks of their lives.

“I think that’s scary,” she said.

“In my opinion, the biggest risk is the fact that if we use antimicrobials in pigs, we may have a pig disease that is no longer sensitive to that antimicrobial.”

Dewey said she wasn’t necessarily against giving medicated feed to nursery pigs. But she said it should be done with veterinary oversight and with products manufactured in Canada, not elsewhere. She also said medicated feed need not be given routinely to grower and finisher pigs.

And OUI should be abolished to ensure quality control and that drugs given in Canada are approved for use here, she said. [email protected]

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