Silage-corn acres have grown almost threefold the past 20 years in the Magic Valley in south-central Idaho – from 78,000 acres in 1989 to 215,000 in 2009, says Steve Hines, University of Idaho Extension educator based in Twin Falls.
That followed early to mid-1980s moves by a number of California dairies to Idaho, showing a growth from 174,000 cows statewide to more than half a million just in the Magic Valley today.
With all that growth come challenges that require research on silage corn, he says.
"There's a misconception that all of the corn research that needs to be done has been done. And that's true – it has been done in the Midwest and farther East.
"But those growing conditions are different from our growing conditions, atmospheric conditions, insects and disease pressure. Certainly our soils are different. So we have to, if nothing else, ground-truth the research done by corn universities in the Midwest and make sure it's applicable here in the West."
Drought-tolerant hybrids are now being studied, for example.
"Of course, we have water issues out here in the West and corn uses a lot of water. We've got to figure out how to grow more tons/acre on less water." Besides conserving water, growers need to learn to remove more pounds of phosphorus from soils to meet nutrient management requirements, he adds.
Growers are also learning how best to use Roundup Ready corn hybrids. "The idea is great in that you plant Roundup Ready corn, it starts to come up and you spray with Roundup. It kills all your weeds and your problems are gone.
"But last year, and this year again, we had rain right when growers needed to be in the field spraying. The weeds got away from them. Some fields were sprayed on time, and some were sprayed late. I've been back in some of these fields, and they've got a really nice crop of weeds coming back up underneath.
"We don't have enough years' experience growing Roundup Ready varieties for a producer to say, 'We're pushing into a wet spring – I'd better use a preplant-incorporate,' " Hines says. "We know that Roundup does not control all weeds perfectly. It doesn't do a great job on lambsquarter and they need something to tankmix with Roundup to control it."
Magic Valley growers are just now moving into minimum- and no-till corn. "Because of our potato-sugar beet production here, heavy tillage has always been a part of what we have done. But there are a variety of reasons why these guys are going into minimum-till. So they're learning how to control weeds, plant corn on corn, control insects. We don't have much for insect problems here with corn on corn yet, but it could be coming. So we're behind the Midwest a couple of decades on minimum-till."
Hines wants to verify whether there is a yield loss after the first year of a corn-on-corn rotation. "I see a lot of conflicting stories and data as I visit with people from different states. We don't have anything that's been done here where we can tell the guys, 'Yes, this is what happens here,' or 'No, this happens here and you can't do that.' "
Editor's Note: In our October eCorn Silage issue, we'll report on Hines' research comparing methods of estimating corn silage pile density.