Up on the Farm

Corn silage 101

Dairy farms are starting to harvest corn silage here in Western New York. It is the most critical field activity of the year after planting because it represents a farms entire year of nutrients for the milking herd and replacement heifers.

Harvesting and storing corn silage poorly can make a significant impact on a farm’s profitability because like pouring concrete, once chopped and stored, it’s what you live with.

Silage is what is made when the entire corn plant including leaves, stalks, cobs and grain are chopped at a very specific length between 3/8 and 5/8 of an inch and as close to 35 percent dry matter as possible.

About 15 years ago, research showed that “processing” or crushing the chopped plant to between one and three millimeters increased digestibility even further, allowing more milk to be produced by cows with the same amount of feed.

Today, processing silage is almost universally practiced.

Once the corn plant is chopped, it is delivered to a silo for storage. Proper storage of corn silage is just as important as getting it chopped at the right moisture and length. Although vertical silos are the iconic symbol of dairy farms, most producers have converted to horizontal silos, which in reality are simply huge concrete floors, with or without walls, where the silage is piled and stored until it is fed.

The goal of properly storing silage is to make it as compact as possible by pressing the air out, and then, keeping it out. Biologically, there are “good” bacteria that use the available oxygen and sugars to multiply rapidly, producing lactic acid which lowers the silage pH to between 3.5 and 5.0.

The bacteria then die and the acid prevents molds and other nasty organisms from growing and eating stored nutrients. Unless more oxygen or water get into the pile, the nutrients in the silage pile are preserved for many months.

Commonly, 10-wheeler trucks will dump their load of silage at the silo where large tractors with even larger blades (like giant snowplow blades) push the freshly chopped corn in thin layers over the growing pile of silage. Other tractors are employed to drive back and forth over the pile to press, squeeze and pack the pile.

This sounds easy, but if you drive past a bunk silo sometime, take a minute to see how high the pile is. Some are 30 to 50 feet high. Now imagine sitting 6 to 10 feet higher in the tractor and driving it as close to the edge as possible. Who said there were no exciting jobs on a farm?

Once a silo is filled and packed, it’s time to be covered to keep out as much air and water as possible. At a value this year of $65 to $80 a ton, it is important to prevent as much spoilage as possible. Many farms are using two layers of plastic. The first is a thin, Saran-wrap like plastic that forms a tight oxygen barrier.

The second is a thicker, durable plastic sheet that is covered with old tires or sidewalls that keeps the plastic tight and in place. Covering silage piles is universally accepted as one of the most important, thankless and despised jobs on a farm. If you want to make yourself a hero, offer to help cover a silo sometime.

Bruce Dehm is an agricultural economist at Dehm Associates, LLC and Chairman of the Genesee Valley Farm Discovery Center in Groveland. Visit www.FarmDiscoveryCenter.org for more information. Email him at bdehm@DehmAssociates.com.