I just got my 9.5-16 R-1s filled with Bio-Ballast at Les Schwab tires. I asked about how much it weighs per gallon. They had to look it up, but found a spec of 9.5#/gal. I think that is about right based on the table in the link above. With new air water valves, and 22 gallons of bio ballast, it cost just under $125, including tax. I hauled the tires in and back and reinstalled myself.
Over on Orange Tractor Talks, there is an article about ballast types. One of the comments was from a guy who claims to be the inventor of Bio Ballast. He says he is from the Pacific NW (probably WA, based on where he said he had distributors.) At that time (2010) his biggest distribution was through Les Schwab. Looks like he has expanded since then.