Såvidt meg bekjent er det ikke gjort videre forskning på dette.
Men siterer her fra "The Content of Psilocybin in Norwegian
Psilocybe semilanceata (A. L. Christiansen, K. E. Rasmussen
and K. Høiland)" publisert i journalen Planta Medica i 1981:
The psilocybin content varied considerably, but does not seem
to be correlated with the geographical location of the mushroom.
There must be other reasons for the variation of the psilocybin
content. We suggest that the concentration of soluble nitrogen
and phosphorus compounds in the soil may play an important
role for the psilocybin content in the mushroom.