Shulchan Arukh, Orach Chayim 82/שולחן ערוך·אורח חיים פ״ב

1The Laws of Dry Excrement, containing 2 s'ifim Excrement which is so dry that if one throws it, it crumbles apart, behold it is like dirt and it is permitted to recite [the Sh'ma] in front of it. And this is if it does not have a bad smell. Rem"a: There are those who say that it is not like dirt unless it crumbles when rolled without throwing it, and such is the correct [opinion] (Rashi and the Rosh on chapter "Mi sheMeito" and Tur)

2Urine that was absorbed into the ground - if it [could] moisten the hand, it is forbidden to recite in front of it. Rem"a: And there are those who say that it is not forbidden unless it is moist enough to moisten another thing, which in turn can moisten another thing. And one may rely on this [opinion].