What impact do bigger corn plants that stay greener longer have on soybean yield? That’s a question OMAFRA soybean specialist Horst Bohner hears a lot these days.
The answer depends on a number of factors explains Bohner in this episode of Real Agriculture Soybean School. He notes that corn is indeed producing a larger amount of residue thanks to bigger plants that stay green longer and are tougher to breakdown. This problem was amplified in fall 2014 when corn residue from a wet, late-harvested corn crop froze quickly resulting in practically no fall residue breakdown. A dry 2015 spring offered little help to ease the problem.
Of course, that situation was reversed in 2015 after an open fall and warm temperatures contributed to early harvest and a high level of residue breakdown.
Bohner says the residue story will change from year to year depending on weather and cropping conditions, but he does believe soybean growers will have to adapt their practices to accommodate increasing corn residue. The big factor to consider is corn yield.
Three years ago, Bohner worked with the University of Guelph to study the impact of corn residue on soybean performance and yield when soybeans follow corn in the crop rotation. The study looked at different levels of residue removal, different tillage practices and compared planter versus drill performance. “At the end of the day, what we really learned is that there’s no problem with no-till soybeans,” he says.
The majority of the sites in the residue research yielded around 170 bushels of corn. By today’s standards, that’s about an average crop. The only challenge for no-till was when a drill was used after corn stalks were chopped and left on the surface. “In that scenario we lost up to five bushels,” notes Bohner. “When we used a row unit planter and pushed that residue away, the yield was regained.”
However, when corn yields hit 220 or better on the yield monitor, Bohner believes farmers need to think about adjusting their strategy to deal with larger residue loads.
“A lot of it comes down to soil type and drainage. If your field is not well tiled you are going to have more response to some tillage and dealing with the residue,” says Bohner. “The other thing it depends on is corn yield. If you are consistently one of those 200-plus guys, it may be time to think about dealing with that residue. It may be as simple as not buying that piece of tillage equipment and going from a drill to a planter unit with even just one good coulter in front of the row unit.”