Do deer, elk ect smell food on other deer.
If one deer finds a good food source that other deer dont know about do the other deer smell it and locate it through droppings? Or how about actually smelling it on the animal and following that animal?
Say I put out peanut butter and one deer locates it. will the other deer coming into contact with that deer figure out that it knows of a food source?

I would say no. Being social animals though, they do follow one another, and tend to do what their friends do. Most resource learning among livestock and wildlife is a product of the mother progeny relationship. Animals will take on new foods quicker if they see mom or peers consuming it.

If one deer can find a food source, any other deer within reasonable range will find it also. Smell is their number one sense.

Of course!

Actually, I would not be surprised if they do. They have very keen sense of smell and are very selective in what they eat. When we were doing "bite studies" with tame deer on the Kerr Wildlife Management Area in Texas, the observers noted that if they reached out to touch a plant to help them confirm it's identity, the deer would invariably come over and sample that particular plant (or that part of a shrub)--even if they had not observed the touching.

Onion rings, maybe.
PBJ uhhh no..

Did anyone get any idea that a deer could smell an unseen food source, growing crops let's say, from a great distance? I've noticed they'll show up in larger numbers than I'm used to seeing just when the milo starts to ripen.

Just cuzz you start seeing them at that time don't mean they ain't always around.

Our radio tracking studies revealed that deer will move far outside their home ranges once or twice a month on what we called "trips". These were not aimless wandering but usually took the form of out and back journeys without much in the way of side to side detours. These excursions seldom lasted more than 24 hours and often went well beyond the limits of the antenna/receiver set-ups that we used in those days. We surmised that this exploratory behavior enabled them to sort of stash away memories of things that could be useful if their home ranges became uninhabitable.

They obviously remember what they find, because we had a doe that spent an entire year on 217 acres, exclusive of periodic trips. When the windmill that she depended upon for water went down, she almost immediately moved her home range to incorporate another windmill almost three miles away. Deer that come to your milo may come from home ranges several miles away. During the rut, bucks will travel many miles from their usual home ranges that they use during the non-rutting seasons of the year.

Thanks for the info Mudhen. It's pretty wide open here and we're on the ground every day. Who knows what they do at night or where they go, but when there's milo in one of our fields and it starts to turn from green to gold and red, the numbers normally seen skyrocket. The next fair patch of cover is on the far side of the next mile south. In between is mostly tall grass and pasture or hay ground. I always suspected they could smell the change in the milo heads. I don't see the numbers change so fast in the bean fields.