For a farmer that works out to a bit less than 10 minutes of harvest. There are big it depends in the above, a high yielding wet corn crop might be a couple minutes, a poor yielding dry crop can be several hours. That is just the grain, most of the plant goes out the back of the combine. A quick search shows forage forage harvestors can do 400 tons per hour, I just took the first number a search found without checking details.