One of my tribe friends, Katrina once posted that she needs a special place to do yoga, and wondered if anyone could relate to that. I found these few verses in the Yoga Tattva Upanishad that relate:

32. Then assuming Padma posture, he should practise Pranayama. He should erect a beautiful monastery with a very small opening and with no crevices.
33. It should be well pasted with cow-dung or with white cement. It should be carefully freed from bugs, mosquitoes and lice.
34. It should be swept well every day with a broom. It should be perfumed with good odours; and fragrant resins should burn in it.
35-36(a). Having taken his seat neither too high nor too low on a cloth, deer-skin and Kusa grass spread, one over the other, the wise man should assume the Padma posture and keeping his body erect and his hands folded in respect, should salute his tutelary deity

You won't find a better authority than that. Given a choice between cow-dung and white cement, I think I would go with the white cement.