Rethinking spraying around water bodies

There's pressure to manage better

Posted: June 9, 2009

Water bodies and crop protection. Ask many farmers how they feel about these two terms and there's a bit of a love/hate relationship. Many farmers see value in water bodies, but in strict management terms they often just get in the way.

So how do you manage? We talked to three people – a conservationist, a provincial weed specialist, and a senior agronomist - and this is their advice:

Should I keep the water body? Perhaps the first question producers should ask themselves is whether the water body is worth keeping. It's for this reason that Jennifer Stoby, a conservation technician with Alberta Environmentally Sustainable Agriculture (AESA), recommends a moderate, benefit-based approach to riparian area management. In other words, the amount of benefit a wetland provides should equal the amount of protection the landowner gives it.

"We agree that in a cropping system you're not going to keep every single slough and pothole, but it's good to have two or three larger wetlands instead of draining them totally off and losing all of the benefits," she says.

Also, in some cases, draining the water body and converting it to cropland may yield no benefit and may in fact present a risk to surrounding cropland when cleared, says Stoby. "If a wetland is drained it can be a source of minerals and salts to adjacent productive cropland. Sometimes there's a salinity problem there but the water was keeping it at bay."

Know the legislation. The clearest indication of distances between spray operations and water bodies is the federal regulations set by Health Canada, says Clark Brenzil, provincial weed control specialist with the Saskatchewan Ministry of Agriculture. These are the minimum setback differences printed on the label of each registered pesticide on the Canadian market.

In addition to these, each province will have its own regulatory structure surrounding the protection of water or other habitat which is usually connected with environmental or safety legislation. "This legislation can be more restrictive than the federal rules, but not less restrictive," says Brenzil.

Maintain a buffer zone. Buffer zones composed of grasses, legumes or shelterbelt shrubs and trees can play a key role in protecting a water body from spraying operations in addition to trapping snow and adding moisture to the cropland, says Stoby.

Perhaps one of the biggest challenges with buffer zones, however, is weed management. Although she comes from a conservation perspective, Stoby also realizes that producers are concerned about how these weeds will affect their crop health. Depending on the situation, she recommends mowing as the optimum method for weed management in buffer zones. "Also, if you run a mixed farm or a neighbour has cattle, they can graze the area late in the fall."

Hand-picking weeds is another safe method of controlling weeds in a buffer zone, says Dan Orchard, a senior agronomist with Sturgeon Valley Fertilizer in St. Albert, Alberta. Another method is to seed the buffer zone to grass in order to "choke out" the weeds. And although there are pesticides available that have been specifically designed for use in riparian areas, Orchard recommends applying these using a controlled applicator such as a wick applicator in which there is direct contact between the chemical and the weed.

However, the bottom line is that all of these methods are, to one extent or the other, time-consuming processes and for this reason Orchard says it's important for producers to use their judgment. "If your buffer zone is full of noxious weeds it needs to be addressed, but if it just has a few weeds here and there it's not the end of the world," he says.

Know your chemicals. Knowing how the chemicals being used interact with the soil is key, says Orchard. "It's important to understand what the chemical you're using can do," he says. "If it's going to be bound to the soil like Round-up, you can get fairly close to waterways, but with chemicals which tend to leave more residue in the soil, you need to stay even further away from waterways."

Watch your slope. Not surprisingly, a slope uphill of the water body places it at a greater risk during spraying operations. This is another instance in which a buffer zone can help, says Orchard. "If you can get the buffer zone to slope away from the water somewhat, you can get that much closer with your spraying," he says.

Consider the wind. As most crop applicators know, wind speed and direction play a key role in airborne spray drift. However, new products such as the agricultural windsock can help producers make better decisions when it comes to spraying and wind. As the wind speed increases, the windsock extends further. By showing wind speed and wind direction, it can help the operator better judge spray drift area and distance.

Notify neighbours. In this day and age, there are growing expectations for producers to notify neighbours appropriately about farming activity which may affect them. Water bodies are sometimes, for better or for worse, used as recreational areas, says Orchard, and it's better to be proactive than reactive when it comes to giving neighbours a heads-up about spraying activity nearby.