I'm laughing at myself... I so focused on the soybean plants I was about to post 'they're soybeans, dummy!!!", then I saw the responses and looked back at the pic and saw the nutsedge in the middle of the plot!!!!
but yes, nutsedge is tough to kill. Roundup will knock it back a bit, but won't kill it. I had a bunch in a new low lying area I turned into a plot a couple years ago. Had a bunch of brushy growth as well, so I hit it with Remedy plus Roundup. THAT did the trick.... no more nutsedge. (don't do that to your beans tho!!!)