thanks for all the input dear people, greatly appreciated. I also have oils and enamel effects at the ready. when I tried the first time, I applied before priming subtle earth and mudeffects from MIG and AK, and vallejo rust to create texture on their shoulders and upper back, and at their waists where they emerge from the ground, then primed it. painted the skin antioch skin, cloth beige ish. and then applied brown washes and enamel effects. but it turned out into a brown blob so to speak, also the texture lost a lot of details because of these steps. it really looked a mess and not in a good way. so that didnt work out.
what I also found out while earth and mudeffects look great when they are used for that and on larger scale models, it did seem to be too big regarding scale for these undead. I thought about doing it with fine sand but mud doesnt look like fine sand in structure, so I am kind of at a loss there, maybe I should skip doing it on the shoulders and upper back, just at the base where they emerge from the ground.
I will try it again with the tips you dear people gave me, thank you all