The goal of this paper is to formulate chances and
limitations of an application of the method of approximate source conditions, originally developed for linear ill-posed problems in Hilbert spaces in [11], to nonlinear ill-posed problems in reflexive Banach spaces in order to establish convergence rates for a variant of Tikhonov regularization. In this context, we update the concept of (local) degree of nonlinearity from [16] to a Bregman distance setting and extend results from [10] and [13] to alternative situations. In particular, we complement the field of low order convergence rates results in nonlinear regularization theory.