Cleaning hay loft

After looking at the picture I would add a thought...
Be sure to add rain gutters and take a close look at the sills and foundation on the left side of the building and possibly the front, as it appears that either it was built too low to the ground or else soil was built up around the structure. It appears in the pic that the siding goes all the way down to the ground, meaning that both siding and sills are in a high-moisture rot prone area. Gutters, to prevent high volumes of water fall, and close inspection/maintenance on that side of the building will be essential in the years to come.
Glad you are fixing that old barn. Too commonly around here it would be allowed to rot down and a pole barn or modern metal barn would replace it. Old barns are unique and individualistic, new ones are all cookie cutters! Same metal roof, same shape and pitch, same sheet metal siding, etc! As the years go by your old barn will become even more valuable as an example of old style craftsmanship.

This is extremely good advice.

I don't want any water added to my hay barn. Scrape with a shovel, sweep.

That packed stuff could just be composting chaff. When I cleaned my barn, it had set "empty" for 30 years. I put all the chaff on the garden to open up the hard red clay. I found out that thistle seeds can be viable for many years. I had millions of thistles growing in masses in my garden.

Get the roof fixed, check the roof rafters, too. Keep the water out. Put the hose away.