Ed,

#1 Might be a 'here' thing, but all the foo-foo dust, foliar stuff, row width, drill vs planter may have an impact, but it is all trumped by planting date - here - a couple hundred miles north of you.

It was also the first sentiment voiced by Dr Palle Pedersen, before he was bought and paid for by Syngenta when he was Iowa State's Soy Extension guru.
He lamented that the first obstacle to increased soybean yields in Iowa was corn. Everybody plants corn, then switches their brain to beans. If they wanted maximum yields for soybeans, they should have been planting them when they were planting corn.

Here, the first thing we do for higher no-till bean yields is have the ability to plant corn and soybeans at the same time, and it pays handsomely.

This will not be a universal fits-all for the North American continent, but probably catches I-80 and north for sure, and probably I-70 if there is research to support it.

Not as sexy as planting with a 20/20 monitor, then tissue testing and spraying micro/fungicide cocktails in-crop, but it works.

#2  The "Critical Weedfree Period" of soybeans is from 1st to 3rd trifoliate. In other words, any weeds that emerge with the crop and are present in this period are costing a lot of yield. Unfortunately, the RR trait made many soybean growers braindead for a decade, so they refrained from a soil applied residual(and/or skipped a burndown), then went out far too late with the "revenge pass" of glyphosate. Did 2 things - cost yield and accelerated the evolution of glyphosate tolerant weeds because we were trying to take down some BIG weeds. High yield soys REQUIRE zero living weeds at emergence & kept clean through to at least 4th tri. 'Most' weeds emerging after this has a negligible affect on yield - not to say I'd ignore it - but depending on species, you can decide how much to invest to protect yield.

These are my First Two. Maybe too simplistic, but if we're going to forget these, all the magic dust and lab samples are moot.

Luke