Forage harvester - forage wagon 320x240

June 2009 silo filling on Ken Mahalko's dairy farm near Ruby, WI, using a John Deere 4020, New Holland forage harvester, and Gehl forage wagon. 2009 has been a dry spring so there's not much plant material on the ground.

Fresh-cut grasses have a moisture content of about 90% which in a silo would result in silage juice liquid leaking out the bottom. The crop is cut with a mower and left in the field to dehydrate down to about 60% moisture content before harvesting. On a hot summer day with the temperature around 80F, the crop can be cut in the early morning and harvested in the evening. Plant moisture content below 45% poses the risk of a fire starting in the silo, due to the heat of fermentation getting out of control.

The spout on the harvester is remote controlled from the tractor, to position the forage stream so as to evenly fill the forage wagon. When turning corners on contoured land the driver must rotate the spout into the box or risk blowing forage onto the ground alongside the wagon.

Storage in silos tends to result in lower retained nutrients compared to silage bales, due to all the various handling processes that allow lightweight plant matter to separate from the heavier but low-nutrient stems. The dust in the air around the forage wagon is actually chopped leaves from the dry plant matter and represents nutrients blowing away in the wind.