How to Determine Corn Silage Moisture

Corn silage chopping should begin soon in Ohio. As described in the recent post authored by Bill Weiss, for good fermentation corn should be chopped when whole plant dry matter is 30 to 35% for bunker silos and 32 to 38% for bags and upright silos.

To check the whole plant dry matter content in your fields, use the following procedure, collect 5 to 10 representative plants from the field. The plants should be uniformly chopped - a chipper shredder or silage chopper provides better chopping than chopping by hand with a meat cleaver or machete. After chopping, mix thoroughly to obtain a representative sample for drying.

Avoid sampling plants from border rows and areas not representative of the majority of the field. Be careful during mixing and subsampling to avoid non-representative grain to stover ratios in the sample to be dried.

Some people prefer sampling only 2 or 3 plants to reduce the chances of a non-representative grain to stover ratio. In this case, it is even more critical that plants be selected carefully to represent the average field conditions. It is best to create two subsamples for % DM determinations, and average the two values.

Dry the sample in a microwave oven or a Koster Tester. Each method requires a good scale that can measure in grams. More information on the microwave oven method is available at http://ohioline.osu.edu/agf-fact/0004.html. For the Koster Tester, refer to the manufacturer's instructions, many of which have posted instructions online.