My father in California had a couple pecan trees. We spent many hours by the fireplace shelling pecans. Every so often there would be an empty nut. I read in a farm paper out there that lack of water causes that. Also, one must remove any husks that might remain on fallen or knocked nuts and then cure (allow to dry) them for a couple weeks before shelling them. Rubber gloves are helpful when removing the husks, as the juice stains fingers. Northwoodswis4