Contour buffer strips - an answer to spring erosion?

Friday, May 1, 2015

Common in the U.S. Midwest, these buffer strips are not so practical for Ontario's terrain. But Jim Clark, working with OMAFRA's Kevin McKague, believes they may help stem the erosion he suffers on his 250-acre farm near Blenheim

by MARY BAXTER

If Jim Clark doesn't have something in the ground during the first spring thaw, be it crop residue or a cover crop, all it takes is an inch and a half of rain and the sandy loam topsoil on his gently rolling 250-acre farm property south of Blenheim slumps towards Lake Erie.

Using no-till to control erosion is not an option. His crops – seeds for corn, wheat, white beans and soybeans – require conventional tillage for industry reasons. So Clark has evolved several strategies to keep his soil in place.

He avoids tillage in the fall unless winter wheat is to be planted, and that crop is always underseeded with a red clover cover crop which is plowed under in the spring, following wheat harvest. Since 1988, he has interseeded a cover crop into standing seed corn as well. Currently it's alfalfa, which he plows in the following spring.

But what to do after a soybean harvest to reduce the erosion risk remained a concern. Now, Clark thinks there's a potential solution – contour buffer strips planted in cover crops.

In the United States, farming on contours and the use of contour buffer strips are regarded as best practices for reducing sheet and rill erosion. The strips are usually planted with a perennial crop (such as grasses, or grasses and legumes) and are kept out of regular crop rotations. Crops are farmed parallel to these. The strips work by slowing and redirecting surface runoff and trapping sediment and anything else that might be travelling with it.

Kevin McKague, a water quality engineer with the Ontario Ministry of Agriculture, Food and Rural Affairs, says contour strips are a common sight in the gently undulating fields of the U.S. Midwest. But they're not so practical for Ontario's topography, which seesaws between hilly or entirely flat terrain. And expecting growers here to farm on contours is just plain unrealistic, he says.

Nevertheless, McKague wondered if there might be a way to incorporate contour cover crop strips during the non-growing season, which studies indicate is the time of greatest risk in the province for erosion and nutrient loss. Could the strips be set up for winter without impeding farm activities at other times of the year? What if the strips were not so big and farmers could drive right through them when returning to the fields in spring?

He knew planting strips of cover crops across a slope wouldn't be as effective as adding a cover crop to the entire field. "This is kind of a stop gap," he says, for people who may not be sure about covering their field all year. "You're talking probably 1/20th of the cost to do something like that, just because you're not working on them near as much but just being strategic in where you put the cover."  

He also wondered if GPS equipment could be used to address the challenge of following a contour to establish the living barrier. The strips could be temporary and introduced after crops like wheat or early harvested soybeans. Or maybe a couple of acres could be scarified and they could be permanent, yet farmers could still drive through them when needed.

"It's not unlike a fence line," he says, noting that, over the years, many fence lines have been removed to improve fieldwork efficiency. The cover crop strip is a way to strategically obtain the benefits of a fence line, only "they're not nearly as permanent. Having these strips permanently would be nice, too, but land is expensive."

Last fall, McKague worked with Clark to evaluate the feasibility of the strips. Timing couldn't have been worse. Months of rain hindered the soybean harvest in the 35-acre field earmarked for the project. Finally, in early November, they planted the strips using a three-point hitch no-till planter and a seed mixture of rye, Austrian peas and oats. "Because it was getting later and later, we went heavy on the rye," says McKague. (Winter rye can germinate and grow at very low temperatures.)

McKague used the elevation drawings for Clark's tile drain system to map the roughly six-feet-wide strips. The width is significantly narrower than the 15 to 30 feet the U.S. Natural Resources Conservation Service recommends, but McKague says the narrower width "does do a lot. It's not unlike a buffer strip, especially if it's thick." He added them in areas known to have problems and in some other areas to help disperse runoff.

Clark says they tried to figure out how to add the directions for the contour strips into the tractor's GPS auto steer system but "we couldn't get the program in to follow those crazy lines." So he pulled the map up on the screen and manually followed it. "That worked really well."

In early March, Clark had yet to see if the strips had been successful. Nevertheless, he says he'd use them again. "It's a no-brainer" to protect soil after a soybean crop. "The cost of seed is minimal. The benefits are huge if it works."

Timing of the planting, though, is key. So, too, is the seed mix.

Clark is not convinced peas offer an advantage in the fall. "I think if you were following something like cucumbers or maybe tomatoes that were off early and you maybe get them (the peas) in the middle of September or sooner, yes, maybe." Oats, he notes, may also be good as long as you get them in early because they can grow in quickly. However, they freeze and die in winter. Cover crops, he says, perform better if they can stay green through the winter, because they can help draw water out of soils in the spring. A dead "strawy" mat cover with nothing green underneath, on the other hand, "stays wet so long because there's nothing there to suck the water out of the ground and the sun can't get to the ground since it's shaded. It's a bad situation all the way around."

McKague is planning on expanding the trial to other farms in the province and hopes to obtain funding. The logistics appear to work. "I don't know about the practicality," he said in March. That's a question he wants to explore, along with the costs of both temporary strips and permanent strips, and if the use of precision farming tools can mitigate expense.     

Brothers Chris and Jeremy Van Esbroeck, who farm near Exeter and Hensall in Huron County, are considering becoming involved. They see the approach as advantageous for protecting fields that are not going back into wheat after a soybean harvest.

Chris, who also works as a soil and water specialist at the Maitland Conservation Authority and has researched on-farm phosphorus loss, says they currently use a minimum till system. In some fields where the brothers have erosion issues, they've put in berms. "We see this (contour cover crop strips) as another layer, another thing to do that would be a low-cost way of addressing the erosion issues," he says. BF