I calculate soil nematodes, mites, and springtails have (in expectation) a welfare of −4.48*10^-6, −1.61*10^-5, and −2.39*10^-5 QALY/animal-year, and an annual welfare of −306 k, −14.2 k, and −10.6 k times that of humans. The annual welfare of soil nematodes being 12.8 times that of soil arthropods suggests the former havebeenunfairly dismissed relative to the latter by people who care a lot about wild animal welfare.
The number of neurons also suggests effects on soil nematodes are larger than those on soil arthropods. I estimate soil nematodes and arthropods have 169 and 52.3 as many neurons as humans, which implies soil nematodes have 3.23 (= 169⁄52.3) times as many neurons as soil arthropods.
The number of neurons also suggests effects on soil nematodes are larger than those on soil arthropods. I estimate soil nematodes and arthropods have 169 and 52.3 as many neurons as humans, which implies soil nematodes have 3.23 (= 169⁄52.3) times as many neurons as soil arthropods.