Crop Scene Investigation - 31 Solved: Why was excess residue accumulating in Richard's fields?

Monday, February 28, 2011

by BERNARD TOBIN
 

The narrow strips of yellow, slower-growing winter wheat plants in Richard's field were the result of heavy levels of canola residue that had been buried three inches below the surface of the strips.

While Richard used a residue manager to incorporate the heavy residue produced by his canola crop, he did not account for the high portion of residue – chaff and pods – that ended up directly behind the combine.

When Richard ran his coulters over the field prior to planting his winter wheat, he did a good job of incorporating the residue, but he needed to do a better job of spreading the high levels of residue that accumulated behind the combine. In these areas, the incorporation work produced strips across the field – about 25-30 feet apart – where a one-inch mat of residue could be found about three inches deep into the soil.

"In this case, the wheat seedling was trying to grow into that mat of residue, which was likely tying up some of the available nitrogen," explains Brian Hall, an Ontario Ministry of Agriculture, Food and Rural Affairs edible beans and canola specialist. He says there may have also been some allelopathic effect – reaction to chemicals released by the canola residue – that also contributed to the slower growth and discolouration.

Hall explains that Richard's approach to residue management was a good one, but growers have to make special note of areas in the field where excessive residue can accumulate. "That can certainly happen behind the combine," says Hall. "In Richard's case, he had a tremendous canola crop that yielded 3,500 pounds per acre. But it also produced a high level of residue and a lot of it ended up right behind the combine."

In these situations, Hall recommends growers examine how the chaff spreader on the combine is working. "Remember, residue management starts the day you combine."

He also notes that a residue management tool has a number of jobs it needs to accomplish – break-up residue, distribute the residue and chaff evenly, partially incorporate that residue and leave the soil in the right condition for the next tillage or planting operation. "That is a tall task, but we are seeing a number of newer residue managers coming onto the market that do an excellent job of managing high residue situations."

It's also challenging for growers to have a tillage tool that will work in all conditions all the time.  Every field is different, which may require a slightly different approach.

A final note: if planting is the next job following the residue manager, Hall recommends checking seed placement and final plant stand to evaluate how the equipment has performed and identify any adjustments needed in the future.

Congratulations to Joe Gordon Elgin Ontario for his correct answer. BF