  Recently Kuzenko and McCarty observed the cancellation of 4-derivative terms
in the $D=4 {\cal N}=1$ Volkov-Akulov supersymmetric action for the fermionic
Nambu-Goldstone field. Here is presented a simple algebraic proof of the
cancellation based on using the Majorana bispinors and Fiertz identities. The
cancellation shows a difference between the Volkov-Akulov action and the
effective superfield action recently studied by Komargodski and Seiberg and
containing one 4-derivative term. We find out that the cancellation effect
takes place in coupling of the Nambu-Goldstone fermion with the Dirac field.
Equivalence between the KS and the VA Lagrangians is proved up to the first
order in the interaction constant of the NG fermions.
