Getting the plaster on an earthbag wall nice and flat can be quite challenging. You can save plaster work by covering the rough plaster with stone. You can buy flat stone facing. This is sandstone. Or you can get stone from out on the prairie or up in the mountains. You want flat stone that will adhere to the wall easily. These are some samples that are commercially available. You just stack them like this. Alternate the seam (joint). And again, instead of buying it, you can get free stone — that’s what I’ve done — like this. Sometimes it’s from an ancient sea bed. It’s out on the prairie or up in the mountains.
Adding stone facing does take extra work, but this is offset by reduced plaster work. (You still need a reasonably flat plastered surface to apply the stone, but it doesn’t have to be nearly as perfect.) It’s best suited for those who dislike or are not skilled at plastering, have the appropriate stone, and love the appearance of stone. One option is to only do lower walls that are most susceptible to moisture damage. Stone is very enjoyable to work with, and if it’s abundant in your area then this is an excellent way to create a durable wall surface.