What makes this work better than any of the other implement shots is the angle. I love that you are on the ground looking straight up, creating a leading line to the sky. The white may be a touch stark, but the shadows and the rusty tools more than make up for it. The sky color is so vivid and is awesome against the other tones. This might even be cool in black and white. I think I'd crop out the right 20% and alleviate those pipes sticking out and then the tools wouldn't be so dead center and those things sticking out wouldn't be a distraction.
8 - Met the Challenge. I like this shot and the perspective. Criticism; Whilst I would like to see a richer color on the spade?, it may blow the white out even more than it already is. I would like to see either the focus further down the handles or else a tighter crop. Perhaps just a sharp focus (or zoom) onto the tools, not sure. More attention to the placement of the tools perhaps, as the shadows could be played on more in my opinion. Creative though.