Interesting picture, the onion doesn't seem to be as sharp as it should be, that may be because of lighting issues, looking at the background, it goes from a brown to a eggshell white. Would like to know how you did this though, it is a technique that would be interesting to copy.
The idea is very nice. Would have been better without the harsh shadow on the background (putting the object further away from the background helps a lot).
The concept of this image is great for this challenge. The technical quality of the image is not so good. Oversharpening is visible as a halo on the border between the black dirt and light colored background. It is also planly visible on the uncut bulbs as well. It gives the image a digitalization quality that is distracting to the excellent concept.