Corn Harvest and Invisible Loss

A few customers have been asking about invisible loss this fall, and I have noticed the topic on some twitter feeds as of late.

Here is what I have learned.

What is Invisible Loss in corn?

Invisible loss can occur when grain dries down too long in the field.  Most corn is mature at 26-35% however optimum harvestability is typically closer to 25% moisture.  However, biological activity continues between 30-15% moisture.  What I read is, that as the kernel readies itself to become a seed ready to sprout, it undergoes a normal process of “respiration”, cannibalizing internal starches and energy, thereby losing test weight.  As an example, corn drying to 15% in the field can lose 10-15% of it’s kernel weight.

Therefore, if you want bragging rights – it is important to harvest early to maximize yield.  For the rest of us, you have to weigh drying cost vs. yield, and determine what the optimum breakeven point is.

Other sources of loss?

More obvious sources of yield loss are downed corn, header loss and ear drop, which increase the longer the mature corn stays in the field.

Other Comments

I found a study done by Perdue over the years of 1992 to 1994, where they confirmed a loss of, on average, 0.9% weight loss for every 1% drop in corn moisture in the field.

This doesn’t happen every year, but the range was 2.7 to 4.3 grams /hL per % moisture drop.  So, corn that started at 360 g/hL dropped on average 3.4 g/hL per point of moisture.

Drying charges factor into this.  If your 200 bu corn is at 25% moisture, and the drying charge is $0.50, your drying charge is $100 per acre.

If that same corn dries naturally to 15%, the drying cost savings can theoretically offset your invisible loss of 20bu per acre, assuming you had no other losses from mechanical or other factors.

• Sources:
• 1.  No-Till Farmer, article Aug 9th, 2016, Gary Woodruff, GSI
  • • • • 2.  Agronomy Department, Perdue University, R.L. (Bob) Nielsen, Professor of Agronomy and,
          G. Brown, Graduate research assistant, Agronomy
          K. Wuethrich, Graduate research assistant, Agronomy
          A. Halter, Graduate research assistant, Agronomy
        • https://www.agry.purdue.edu/ext/corn/research/rpt94-01.htm