Am i the only one not enjoying these?

Why wouldnt it be Decomp and /FA -> /ACG?

Heres my logic:

If the soil is depleted (Decomp). This is Sufficient so "Decomp->"

additional crops cannot be grown (ACG). This is necc so "Decomp-> /ACG"

unless fertilizer is applied(FA). This is Sufficient but negated to "Decomp + /FA -> /ACG"

How is this not right?