The dry matter (DM) content of corn silage at harvest will significantly influence the amount of nutrients delivered and the nutrient value. Before deciding on a target DM for corn silage harvest, talk with your nutritionist about your silage goals and feeding strategy.

Heguy jennifer
Dairy Farm Adviser / University of California Cooperative Extension – Stanislaus County

When buying or selling silage, the dry matter-to-moisture ratio will determine your final price. How often samples are taken during harvest to estimate DM content for the entire field will influence how accurately you can determine that ratio. Our research shows that sampling frequency (number of samples and timing) can significantly influence the price you’ll pay for a field of corn silage.

Silage is normally sold on a 30 percent DM (70 percent moisture) basis. For example, you may agree to pay $75 per ton for silage at 30 percent DM, but the price you actually pay should reflect the DM coming off the field. Early communication with all involved parties will aid in a smooth negotiation process.

Let’s look at an example. Dairy producer, Joe Smith, is buying silage from his neighbor. He has agreed to pay $75 per ton for the silage corn harvested off of the 23 acres. Joe weighs every truckload of silage coming onto the property, so he knows the total weight of forage delivered. Now Joe needs to monitor the DM coming off the field and adjust his purchase price accordingly.

correcting purchase price of dry matter

Joe agreed to buy the field of corn silage for $75 per ton at 30 percent dry matter (DM). After careful sampling, Joe determines the average DM delivered to his pile was actually 28 percent. Should Joe still pay $75 per ton? Below is an equation that can be used to correct the purchase price for DM:


So, at 28 percent DM, the purchase price would be: 28/30 x $75/ton = $70/ton.

If the field was harvested at 32 percent DM, the purchase price would have been: 32/30 x $75/ton = $80/ton.

How we sample a field of corn silage for DM adjustment can have us paying too much or charging too little for corn silage. Joe carefully sampled the purchased field – what does that mean? Taking a single sample to represent an entire field of corn silage is never a good idea, so sample the field often for best results.

When we followed larger fields of corn silage, ones that took 10 or more hours to harvest, taking a sample every hour was the best way to estimate DM of the entire field. When fields are on the small side, or take less than 10 hours to harvest, sampling more frequently than hourly may be warranted.

moisture in dry matter

Taking 10 consecutive samples of truckloads dumped at the structure yielded better results on the smaller field (see Table 1, Field 2) . In the table below, you can see three fields of corn silage that we followed and what the extreme prices would be based on sampling method (assuming $75 per ton of corn silage). PD

To see more details regarding this work, visit the UC Cooperative Extension website .

Jennifer Heguy