Silage Source Considerations

Dr Brent Bean, AgriLife Extension agronomist in Amarillo, and Dr Mark Marsalis, New Mexico State University agronomist in Clovis, recently released a paper identifying differences between corn and sorghum silage.

The main advantage of corn over sorghum is that corn tends to be a more consistent product from a nutritive value standpoint, Dr Bean said. However, for corn to be of high nutritional value, it must produce large amounts of grain.

In periods of drought, such as 2011, grain production from corn can be severely limited, he said. In those areas where rainfall and irrigation is expected to be lacking this year for good corn silage production, sorghum should be considered.

According to the paper, some considerations in determining which forage source to plant include:

• Corn seed will typically cost about $95 per acre compared to $15 per acre for sorghum.
• Full-production corn silage will require 20-25 inches of irrigation water, compared to 14-18 inches for sorghum silage.
• Fully irrigated corn will typically yield between 27-32 tons per acre compared to sorghum silage at 20-26 tons per acre on average.
• Corn typically will be of better feed value than sorghum, however some sorghum hybrids have been shown to be equal in nutritional value.
• Sorghum is better able to withstand periods of drought than corn.

Dr Bean said whether selecting corn or sorghum, it is important to choose a hybrid that is adapted to the area.

Any corn hybrid that is grown for grain in a particular region can potentially be used for silage production, however some seed companies do designate some hybrids specifically for silage production, he said. They are typically a little longer in maturity than those for grain production.

Variety trial data from the Texas South Plains, Panhandle and Central Texas area can be found at http://varietytesting.tamu.edu. Results from New Mexico variety trials can be found at http://aces.nmsu.edu/pubs.

When choosing a sorghum hybrid for silage production, both yield and nutritive value should be considered, Bean said. There is a wide variability between hybrids, and which value should be emphasized will depend on how the silage is to be utilized. For lactating cows, feed value is more important; for dry cows, yield may be more important.

For a complete discussion of forage sorghum production, see the publication ‘Western Forage Sorghum Production Guide’ at http://amarillo.tamu.edu/amarillo-center-programs/agronomy/ .