Proper corn silage harvest
As the summer comes to a close farmers need to think about when to harvest their corn for silage. Proper silage harvest management is the key to quality feed all year long. With forage inventories being low this year, it is more important than ever to make sure that the aspects of silage harvest we can manage, we do well. These aspects are harvesting at optimum moisture, proper chop length, and achieving sufficient kernel processing, followed by recommended storage practices.
Ideal harvest moisture is the single biggest key in harvest management for quality corn silage. Harvesting corn for silage too early (high moisture content) or too late (low moisture content) can affect forage yield, quality and silage fermentation. Current recommendations are to harvest at whole plant moisture content of 60-65 percent for upright stave silos, 60-70 percent for silo bags and 65-70 percent for bunker silos.
Corn harvested at too high a moisture promotes clostridial fermentation over lactic acid fermentation. Silages wetter than 70 percent moisture often leach out essential nutrients and sugars, lowering the energy content of the silage. Silages above 70 percent moisture generally have decreased starch as a result of an immature plant, which in turn lowers the energy density. When silage moisture drops below 60 percent moisture, fiber quality and starch digestibility suffer, packing becomes a problem causing inadequate fermentation. Whole plant moisture content of corn typically changes by 0.5 percent per day and in dry conditions can change by up to one percent per day.
Corn that is affected by drought conditions will look terrible with leaves that are dried and shriveled. Leaves make up only a small portion of the corn plant and these plants will have a moisture content higher than people will expect.
Corn plants affected by drought may have excessive nitrate issues. As the corn plants recover, nitrates are taken up at levels greater than they can assimilate. This causes excessive amounts of nitrate in the plant that can be toxic to livestock. Ensiling corn silage will reduce the number of nitrates in the plant materials by one-third to one-half during the ensiling process. To reduce the nitrates through the ensiling process, allow the silage to go through the 21-day fermentation process before opening the bunker to feed.
Once the corn silage is out of the field, proper storage is essential. Pushing all the air possible out of the silage during storage is imperative for proper fermentation. Most importantly, seal the pile or bag as quickly as possible and ensure any holes are mended; oxygen is one of the biggest nemesis to proper fermentation.
The following are sug-gestions to reduce handling, harvesting and storage problems. To harvest an uneven field, begin chopping the cornfield when the majority (>50 percent) of the plants within the field are at the correct moisture for the storage structure. If developmentally uneven plants are randomly scattered within a field, there should be no fermentation problems because adequate mixture of material will occur as plants are chopped and packed into the silo.
The formation of layers in the silo that are significantly wetter or drier than the optimum moisture for the storage structure can cause problems. This would typically be seen with large problem areas in a field or when switching to fields that differ significantly in moisture.
The best way to harvest a field with a large problem area depends upon row orientation. If an uneven area is located in a field so that each pass of the chopper moves through the area, then enough mixing will occur for proper fermentation.
However, if the area is orientated to the rows so that the chopper will not move through the area with each pass, then the area should be segregated and harvested separately.
