Looks nice. You can blend unlimited textures using lerps. General approach is to start with a base texture, and lerp things into it one after another. This is equivalent to stacking alpha masked textures, and also lets you easily blend alpha masked textures (multiply the factor given to lerp by the alpha component). Its also possible to use the alpha to make different parts of the texture fad in first (so the grass blades are there or not rather than the texture fading in, or making nice transitions from scattered rocks to solidly rocky. Translucent rocks just look bad)
Anyway, looks quite nice. Well done.