When I planted my first soybean crop in 1987, it was with our "corn planter" the name we often use to refer to what you Brits call a precision planter because for years all they were used for was planting corn(maize). They were in 30 inch rows, about 8-10 seeds per foot of row. In those days bean seed came in a 50 or even a 60 pound(one bushel) bag and cost at most $15 per bushel. In the early 90s a neighbor tried a novel new approach to planting soybeans(we often simply call them "beans"), he seeded them with his 7.5 inch wheat drill. As time went on it became more and more accepted to plant with a drill, most guys used about 10-15 pounds more seed per acre to compensate for poorer emergence brought about by more haphazard seed depths and spacing. By 2000, my guess is that 50% to as many as 80% of the soybeans planted in my immediate area(say a 20 mile radius of my farm) were drilled.
During the "world food crisis" of a couple years ago, the price of GM soybean seed skyrocketed, and as prices eased for the raw soybean, the price of seed kept going up. New for this year I will no longer be able to buy my seed by the pound, they will come in 140000 count sacks. For years our corn has come in 80000 kernel units, now it is soybean seed. With seed costs now approaching $50 per acre for soybeans, rivaling corn, drills are being relegated to drilling just wheat again, and soybeans are being planted more precisely with "corn planters" some with 15 inch splitters. With at most two weeks to make up my mind, for the first time in 15 years there will more than likely be no more than 25 acres of soybeans planted with a drill, if any at all. While I would like to purchase a 12/23 split row planter, I will probably just return to the much more economical 30 inch row, and sacrifice a bushel or so of production an acre. I guess this is sort of a "back to the future" moment.