- Let's start with the herbicides first. In short, outside of glyphosate (14 to 25 day, depending upon timing/use) and a handful of pre's and posts (please refer to Table 3-3 in A3646, Pest Management is WI Field Crops) most soybean herbicides are listed as "not permitted" for forage use.
- Next, many common insecticides used for soybean aphid management implicitly state "Do NOT graze or feed treated forage or straw to livestock" (please refer to Table 3-8 in A3646, Pest Management is WI Field Crops) .
- Lastly, fungicide labels are as equally exclusive with pre-harvest intervals ranging from 14 days to "Do NOT graze or feed soybean forage or hay" (please refer to Table 3-12 in A3646, Pest Management is WI Field Crops) .
If you somehow pass the gauntlet of "Do not" or "Not Permitted" and the forage value is greater than the grain value then the highest protein and yields are obtained from soybean harvested at the R6 to R7 growth stage. Harvesting soybeans for forage between the R1 and R5 stage will result in a very high quality silage, but dry matter yields will be reduced significantly. Forage quality will be reduced from R5 soybean forward if a conditioning process is used during harvest as conditioning will cause significant seed shattering. For additional information please refer to Soybeans for Hay or Silage.