My shoe has lost it's sole. Do I fix? What glue?

My farm shoes are coming apart at the soles.  I'm trying to decide about repairing them.

I could buy regular shoe glue but was wondering if there are natural alternatives.

So basically two questions:
What natural glue works on shoes?
When is it time to not repair and get new shoes?  

Of course much depends on the original cost of the boot/shoe and the condition the upper is in.  I have used both shoe glue and epoxy with mixed results. Do make certain the boot is stuffed with newspapers/rags to help it maintain its shape while drying. Maher sure the sole is clamped/under a weight while drying. Allow 2x the suggested time for drying.

Any more I buy higher quality boots. It pays in the long run.  I only glue in an emergency situation.  Otherwise, they go to a pro for the repairs.

At the time the sole flopped off of the upper leather of my black Ugg boot I was caulking the woodstoves with black high temp silicon caulk. There is always leftover caulk! So I squirted a bunch on the sole from the instep to the toe. Then I clamped it with black office binder clips. It has held up really well. This was their third lease on life. A couple of years ago the tread wore off the sole and the shoe repair guy said they couldn't be re-soled. When I told him the problem - fear of slipping - he came up with a brilliant solution. He ground some grooves in the bottoms to create "new" tread. These are the boots that keep on giving some 15 years after purchase.