Bury crop residue or let it lie: no easy answer

The benefits of strategic tillage to incorporate surface residue into the soil where it may do more good is being hotly debated.

Proponents of the practice say there are major benefits to be had by moving the organic matter into the soil.

Others say they can’t make a definitive decision because they haven’t seen enough research relevant to their soils.

The University of Saskatchewan has examined the question and came to the conclusion there’s no major Earth-shaking revelation to be had one way or the other, according to soil scientist Jeff Schoenau.

“We’ve all heard that philosophy of burying thatch. We did research back in the mid-2000s looking at employing a single strategic tillage operation,” says Schoenau.

“One of our observations was that it reduced nutrient stratification, but it didn’t really have any major impact on the availability of phosphorus or on crop growth. But when we did incorporate that thatch layer, we saw some evidence of immobilization. That thatch layer has a pretty low nitrogen level and a high carbon-to-nitrogen ratio. If you do till it in, probably need to apply extra nitrogen fertilizer to account for that additional nitrogen tie-up when you work the surface straw down into the soil.

“Overall, the effects were huge from a single tillage operation on a small plot. But I also have to say that when you start to cultivate entire large land areas, entire fields, that’s when the negative impact of erosion shows up. That doesn’t happen on a small plot.”

Contact ron.lyseng@producer.com

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