What if any prohibitions are there on the intentional use of excrement from unclean animals as fertilizer for crops? Must it be buried, for example?

Does the same apply to the intentional use of unclean animal remains as fertilizer? For example, if restaurant refuse that likely contains non-kosher animal remains is composted and used to fertilize soil, into which seeds were planted? Or if the carcass of an animal that died of itself was similarly used?

1 Answer 1


We are allowed to "derive benefit" from unkosher animals. How does using their excrement or carcasses not fit in that leniency? Besides, anything kosher that you eat may have somehow grown using something unkosher, and we do not check for that.

  • I remember that if an animal carcass was found floating in a lake, the water in that vicinity is to be considered unclean for a time. (I can't find that now, it's hard to search for.) I was wondering if there was a similar concern for the soil, if plants could be considered tumah from the conditions of the soil they are grown in.
    – wberry
    Commented Jan 16, 2022 at 19:33
  • And I am aware of Rabbinic guidance of an olive's bulk of flesh or a barley grain's bulk of bone to convey corpse contamination, which would seemingly imply that if there is any such uncleanness conferred to plants, it could potentially be obviated if the flesh were sufficiently composted and bone sufficiently broken down by machine first.
    – wberry
    Commented Jan 16, 2022 at 19:55
  • 1
    Rules of ritual purity and kashrut are not the same thing. Commented Jan 16, 2022 at 20:47

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