A Noetherian local ring (R, m) is called Buchsbaum if the difference e(q, R) − ℓ(R/ q), where q is an ideal generated by a system of parameters, is a constant independent of q. In this article, we study the tight closure analog of this condition. We prove that in an unmixed excellent local ring (R, m) of prime characteristic p > 0 and dimension at least one, the difference e(q, R) − ℓ(R/ q * ) is independent of q if and only if the parameter test ideal τ par (R) contains m. We also provide a characterization of this condition via derived category which is analogous to Schenzel's criterion for Buchsbaum rings.2010 Mathematics Subject Classification. Primary 13A35; Secondary 13H10. Key words and phrases. tight closure, system of parameters, parameter test ideal, Buchsbaum ring, generalized Cohen-Macaulay ring.LM is partially supported by NSF Grant DMS #1901672, NSF FRG Grant #1952366, and a fellowship from the Sloan Foundation. PHQ is partially supported by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 101.04-2020.10.1 This characterization of Buchsbaum ring is well-known to experts but we cannot find an explicit reference in the literature, thus we include a short explanation in Remark 3.4.