One of the most challenging and laborious textures that confronts me and the way I work with graphite, is a large area of a soft, even tone of mid value grey as in the piece currently on the drawing board with its large areas of dried, sun baked earth. It's a challenge but it's also fun to juxtapose that rather smooth texture up against a completely different texture, such as the undulation and fissured, crinkly surface of a African baobab tree. The way I go about accomplishing that subtle even toned grey is, as I have talked about many times before, to layer various grades of graphite through cross hatching and little circular motions. Since I work on a slightly textured Bristol board, I tend to just graze the surface of the 'paper' with soft strokes of the pencil tip and let the graphite adhere to the upper surface of the texture on the first few passes and crossing hatches. As I progress with layering, the graphite tends to fill in the gaps as I go back and forth, horizontally across the paper and then at an angle and then vertically with some small circular motions thrown in for good measure. The result is a relatively even base tone that I can then go over and begin to flesh out with dimensional additions by scratching in dark areas to give depth.
In the shot below, you will see the five basic pencils that I have been using so far to achieve that texture - from left to right 5H, 2H (in the red lead holder), 3H (in another lead holder), 8H and 6H. In no particular order, each graphite grey value is softly run across the paper and another, either harder or softer grade of graphite is layered over that one and so on and so forth, till I get a desired tonal value. You'll note also that several of the pencil points have been blunted so I have both a flat surface that gives a larger stroke, and by turning that same point slightly so that the sharper side of the tip is made use of, the line becomes narrower and a bit darker as it is applied. I keep going back and forth, turning that sort of pencil point as I work with that particular pencil to vary the value that ultimately is formed once an area is covered with that layer. This is all 'base work' right now to establish an under tone that I will, eventually, add other details to to give more depth and nuance.