Having been raised on a farm and actively farming with my husband all these years (I am now 70 and still drive the combine) I would go with the plowed furrow suggestion by my-ty. That is what a freshly planted field looks like before the corn or beans come up. Then share that with the person receiving the quilt. It will be much more meaningful. I also agree you need more quilting in tractor squares. What about just doing an echo stitch 1/“ away from tractor and another line of stitching 1/4” away from edge of block.