A report from the AgTech Centre

Direct seeding farmers fighting heavy crop residue may soon have a new seeding tool to help increase seed-to-soil contact and ultimately improve crop yields, says an AgTech Centre engineer.

The device, known as a residue manager or wheel, mounts just ahead or to the side of the disc or hoe type openers on seed drills. The residue manager, depending on make, looks like a notched disc or a fingered wheel. It is intended to either push residue away from the opener or hold straw and chaff in place so the hoe or disc opener can better slice through it, allowing for optimum seed and fertilizer placement.

"We've seen improved germination, which should translate into higher or more uniform yields," says Lawrence Papworth, a project engineer at the Lethbridge-based Centre. In 2003 the crop plant count increased by an average of nearly five percent. However, in their research, plant counts ranged from a low of nearly minus 11 percent, increasing to a high of 56 percent. Field evaluation of different makes of residue managers will continue through 2004. "In most cases, the residue manager enables the openers to put more seed and fertilizer in contact with the soil, which should increase the germination rate," says Papworth.

Heavy crop residue often impairs seed drill operation either by bunching in front of the opener, or in the case of disc-opener systems, by getting under the disc - a problem referred to as hairpinning - as it slices along the ground. In both cases, seed and fertilizer get placed on top of the residue and don't make proper contact with the soil.

"Our research demonstrates residue managers are one way for producers to keep residue under control in a direct seeding system," says Papworth. "As more and more farmers adopt direct seeding practices, they will have to address residue management."

Coping with heavy crop residue obviously isn't an issue in drought years, or in drier areas where crops tend to be shorter and lower yielding. But under irrigation, or in higher moisture growing conditions where producers see higher yields and more straw and chaff production, residue management is important.

Before direct seeding and conservation farming techniques became common practice, baling straw and/or tillage were commonly used to remove straw or incorporate residue.

"Now it is important in direct seeding systems for producers to manage residue at harvest," says Papworth. Equipping combines with straw choppers and chaff spreaders to distribute residue evenly over a field is one option. As well, producers can make a pass over a field with a low-disturbance heavy harrow to better distribute the residue.

"But if you're in a situation where even those treatments leave a high concentration of straw and chaff, equipping the drill with residue managers might be an option," he says.

Residue managers have been commonly used in the United States for precision planting of high-value crops such as corn and soybeans. They work well to help planters seed through heavy trash such as corn crop residue.

While residue managers appear effective for working through cereal crop residue in the AgTech Centre trials, Papworth says cost of equipment will likely be a major drawback for most Prairie producers. Some U.S.-made models being evaluated by AgTech Centre engineers sell for about $250 US per wheel.

On a three or six-row corn planter that's not a huge investment. But a 36 foot-wide grain drill set at 7 1/2 inch row spacing, for example, would require nearly 60 residue managers, at a cost of about $15,000 US.

A Saskatchewan-based manufacturer has also developed a residue manager, which will cost about $130. "That would bring the cost down to about $7,500 to outfit a 36-foot drill, which is more affordable, but still appreciable," says Papworth. "However, in heavy residue situations it may be the best option."

The AgTech Centre research hopes to quantify the benefit of the residue managers in terms of improved crop emergence and yield, says Papworth. "As producers continue to switch to direct seeding to capitalize on the benefits of reduced soil disturbance and moisture conservation, we need to see if the economics of using this tool is justified."

The AgTech Centre is part of the Alberta Agriculture, Food and Rural Development Agricultural Engineering Branch. Its mandate is to support all aspects of agricultural sustainability.