Estimating corn silage yield price

Harvesting hay silage
Harvesting hay silage in Wayne County.

Corn silage season is starting. As I was traveling the state last week, I saw the first field being harvested. The producers said it was right at 30% dry matter so more harvest will be underway across the state soon. 

For many producers, a successful corn silage harvest sets up the operation’s ability to maximize milk production for the next year. As you prepare for corn silage harvest, it can be helpful to estimate how many tons per acre each variety will yield so that you can make sure you will have enough tons of corn silage. 

If you happen to be purchasing corn silage, having the agreed-upon price prior to the harvest arriving is critical. 

Estimating yield

To estimate corn silage yield, harvest 1/1000th of an acre, cutting plants at 8-12 inches above the ground based on the height you run the forage harvester in three to five areas of the field. 

The length of row to harvest that equals 1/1000th of an acre depends on your row spacing. For 30-inch rows this length equals 17 feet 10 inches; 36-inch rows harvest 14 feet 5 inches; 20-inch rows harvest a length of 26 feet, and in 15-inch rows harvest 34 feet. 

Weigh all plants harvested in the area equal to 1/1000th of an acre and divide the weight by two, giving you the estimated tons per acre harvested. This gives you tons of as-harvested forage at the current moisture; if tons per acre of dry matter is needed, chop and take a silage moisture sample. 

As plants reach harvest maturity and moisture, the starch weight increases but moisture leaves decreasing plant weight. 


When pricing standing corn, it is important to remember that corn silage is not required in a dairy ration but the nutrients it provides are required. They may come from other sources if a cheaper option is available. 

The two parts to corn silage are the grain and the stover. The easiest part of pricing corn silage may be pricing the grain portion besides estimating grain yield. 

Grain yield can be estimated in multiple ways. The first is to leave multiple test blocks in each row that can be harvested as dry corn for yield. The next is to use an equivalent factor that every 0.15 tons of corn silage harvested per acre at 65% equal one bushel of corn grain per acre. This method requires you to have an accurate tonnage of silage harvested and correct that tonnage to 65% moisture. 

The last commonly used method is to use the grain yield estimate calculated by crop insurance. Once a yield determination method is agreed upon, the price per bushel needs to be determined. The price at a local elevator that the corn could be sold at either as a spot sale or as a forward contract or delayed pricing option is often used. 

For example, if grain yield was determined to be 197 bushels per acre and the local December cash price is $5.97 per bushel, the grain value per acre is $1176.09. 

The next calculation is for the value of the stover which often equals the current price of grass hay which locally is $125/ton. A 29.5-ton as-fed yield is about 50% stover as-fed, equaling 14.75 tons. This needs to be corrected to hay dry matter which is usually 90% dry matter. 

To do that, multiply tons of stover by (percent silage dry matter divided by hay dry matter of 90%) in our example 14.75 ton*(.35/.9) = 5.74 tons of grass hay equivalent. Current grass hay price of $125/ton times 5.74 tons equals $717.50/acre. Add together the grain value of $1176.09 plus the stover value of 717.50 for a total corn silage value of $1893.59 per acre. 

The value per ton is then the value per acre divided by tons harvested per acre (i.e. $1893.59/29.5 tons per acre = $64.19 per ton in the field). 

Since the grain producer will not be harvesting the crop, there should be a deduction of harvest cost. Based on Ohio custom rates, to harvest, haul and fill a corn silage bunker is $10.50/ton. This harvest cost deduction gives or our corn silage a value of $53.69 per ton. 

Negotiating corn silage price and estimating yield prior to harvest can make things go just a little smoother.


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