At some point you cannot use higher resolutions or bigger textures anymore (eg: 2048*2048) this is where multitexturing may become useful. Take a grainy, sandy tiling texture and apply it as a further texture layer (see entitytexture optional parameters). Additionally, use blendmode 5 or so for the texture, together with a texture that has an average color of 128,128,128. Now when you're close to the terrain, the grainy texture is visible, when far away the blurry texture will dominate.