It doesn't quite look like what I've had, but sometimes photos don't give the best representation. Usually early on in my caves, when desired species haven't yet gotten a foothold and can outcompete others. At any rate, a bright neon yellow for me, has been fusarium. There's also the possibility of pseudomonas flourescens, but your photo doesn't look bright enough for either, to me. Neither is harmful, though they can give off-flavors. Keep in mind that my ID'ing experience is pretty limited, and what I know I got from Linuxboy.
To me, looks more like just a normal early growth linens, possibly in tandem with other corynebacteria and/or yeasts, which can lend some yellow hues. These typically darken with age. See
here.
When you say earthy smelling - do you mean, like humus, like mildew, or a dank, moldy cellar? Or more mushroomy? Or more "funk," something having a more meaty, savory note? Also, you've got substantial blueing, so is it possible you're smelling this as part of the bouquet mix?
