  We embed the Loop Quantum Gravity Barbero-Immirzi parameter and field within
an action describing 4D, $\cal N$ = 1 supergravity and thus within a Low Energy
Effective Action of Superstring/M-Theory. We use the fully gauge-covariant
description of supergravity in (curved) superspace. The gravitational constant
is replaced with the vacuum expectation value of a scalar field, which in local
supersymmetry is promoted to a complex, covariantly chiral scalar superfield.
The imaginary part of this superfield couples to a supersymmetric Holst term.
The Holst term also serves as a starting point in the Loop Quantum Gravity
action. This suggest the possibility of a relation between Loop Quantum Gravity
and supersymmetric string theory, where the Barbero-Immirzi parameter and field
of the former play the role of the supersymmetric axion in the latter. Adding
matter fermions in Loop Quantum Gravity may require the extension of the Holst
action through the Nieh-Yan topological invariant, while in pure, matter-free
supergravity their supersymmetric extensions are the same. We show that, when
the Barbero-Immirzi parameter is promoted to a field in the context of 4D
supergravity, it is equivalent to adding a dynamical complex chiral
(dilaton-axion) superfield with a non-trivial kinetic term (or K\"ahler
potential), coupled to supergravity.
