From the summary of the paper, to myself it appears its authors seem to have a view that the majority of farm waste isn't recycled and go so far as to include grazing livestock in open fields, which as far as I know, most grazing livestock poop where they feed and yes sometimes the farmer /workers needs to use machinery (eg using harrows or a bar) to spread out any heavier accumulations.
That aside, from its summary, the paper seems to miss implications of heavy metal loading [1] [2] [3] in human waste and the summary doesn't mention what level of treatment processing they had determined to recycle. Typical modern waste management employs breaking the waste down with bacteria and produces a significant amount of methane in the process and are left with biosolids. [4] Such biosolids are very valuable to a farmer not for the NPK nutrients but supplying carbon for soil improvement. Higher carbon soils seem to have better water holding capabilities [5][6] along with a much better soil microbiome which is beneficial for plant growth.
[1] https://journal.gnest.org/system/files/2024-08/gnest_06247_f... [pdf]
[2] https://set.adelaide.edu.au/fertiliser/system/files/media/do... [pdf]
[3] https://www.fao.org/fileadmin/user_upload/GSP/INSOP/INSOP_2m... [pdf]
[4] https://modernfarmer.com/2014/07/stink-human-poop-fertilizer...
[5] https://www.abc.net.au/news/2018-07-07/sydney-waste-turned-b...
[6] https://www.abc.net.au/news/rural/2022-03-19/farmers-fertili...
...thereby freeing up the nitrogen and phosphorus supplies for explosives and incendiaries?
Lagniappe: https://www.youtube.com/watch?v=TDS1u72qv6s#t=118s