How you sample a field of corn silage for dry matter adjustment affects the forage’s price.
With corn silage prices reaching $75 to $95 a ton this summer, it’s a good time to think about your silage goals, says Jennifer Heguy, UCCE Farm Advisor for California’s Merced, Stanislaus and San Joaquin Counties.
Traditionally, corn silage is purchased on a 70/30 basis; that is, 70% moisture and 30% dry matter (DM).
"Let’s assume we’re buying a field for $75/ton," Heguy says. "What happens when the corn silage is delivered at 28% DM? Is the value still $75/ton? What if it’s delivered at 32% DM?"
Heguy shares an equation that can be used to correct the purchase price for DM:
Actual DM% x $/ton = Corrected $/ton
• At 28% DM, the purchase price would be: 28/30 x $75/ton = $70/ton
• At 32% DM, the purchase price would be: 32/30 x $75/ton = $80/ton
"It’s important to remember that as corn matures (DM increases) and starch content increases, fiber quality declines," says Heguy. "This trade-off between starch content and digestibility of forage will affect how the silage is incorporated into rations. It’s also a prime example of why it’s imperative to talk with your nutritionist about your silage goals before making a decision to harvest at a certain DM."
How you sample a field of corn silage for DM adjustment can also have you paying too much or charging too little for corn silage, she adds.
Heguy’s advice? Sample the field often for the best results.
"When we followed larger fields of corn silage, ones that took 10 or more hours to harvest, taking an hourly sample was the best way to estimate DM of the entire field," she says.
When fields are on the small side or take less than 10 hours to harvest, sampling more frequently may be warranted. Taking 10 consecutive samples of truckloads dumped at the structure yielded better results on the smaller field (at 23 acres), reports Heguy.
The table below shows three fields of corn silage that Heguy and her team followed, and what the extreme prices would be based on sampling method at $75/ton corn silage.
This table shows the three fields of corn silage that Jennifer Heguy and her team followed, and what the extreme prices would be based on sampling method at $75/ton corn silage.
Protocol on mixing and sampling composite samples can be found here.
Heguy made her comments during a UCCE Silage Day earlier this month in Modesto, Calif.