Many in this area (NE IL) are asking the same question re. 15 vs 30". I think one has to realize that beans seem to respond differently in different geographical areas. The other posts on this topic make that obvious.

The ONLY b&wh data I can find is from Becks. We don't plant their stuff, I just see their plots. They show a 1.5 bu advantage to 15" rows over 10 yrs of data. They also had 7.5" rows in the mix. They mentioned that each row width won the plot in some year.

http://www.beckshybrids.com/research/2008/pg40-pg41.pdf

1.5 bu will make you about $18 @ $12/bu beans. That selling price is arguable. Adjust it if you want. I would say that MOST farmers (not agronomists or advisors...but farmers!) that I talk to reduce bean population from 15" to 30" rows by about 20%. If they were 150K in 15" rows, they drop to 120K in 30" rows. Not science, but everyday life fact. RR2 beans this yr were $50/ba. We're told to expect $60 in 010. I think there's 150K beans in a unit (bag). So, reduce your population by 20% & save $10-12/A. I realize the answer to this will come from some saying that you should plant 120ppa irregardless of row width. They could be right also, but I don't know many doing that. Again, not science but daily life facts....here. So now, you have maybe only a $8 gain. That's eaten up in machinery costs pretty fast. Even if you're adament about used equipment, you're running twice as many openers, etc up & down the same working width, thereby doubling your machine wear.

Someone mentioned "getting beans out of the ground". We've rotary hoed 15" beans in the past & you have to assume that you will damage many of the beans that your tractor runs over. That's called collateral damage I think. However, if you hoe 30" beans, there should be no tire damage. Hoeing beans does take proper timing to avoid breaking good plants. I also realize some of you cut up your hoe for scrap long ago.

If weed control (or inability to control) is a personal issue, then I think we all agree that narrower row beans shade earlier, giving nature a better chance to help w/weed control. But if that's so, then the real answer is rows narrower than 15".

Yield increases in beans have been less than spectacular in this part of the world. I realize that in parts of MN & a few other states, that yields have multiplied greatly in recent years....not here. Many are asking what to do to get that "kick" that we're all looking for. So, one has to consider how far away from home is your comparative data.

Thanks for asking this question. It is asked often.....here.