Terra Preta Arqueológica (TPA) are soils that are characterized by their dark color and high Ca, Mg, Mn, Zn, P, and C content. The source of these elements can be of animal or vegetal origin (Kem 1996). Among the vegetable sources is the açaí, which produces a large amount of waste that is discarded (about 80%). Through bibliographic data, the açaí has been used since prehistoric times (Corrêa, 1926) and continues as an important food source until the present day. This work aims to determine the content of pH, Ca, Mg, Mn, N, Fe, B, Cu, C, P205, K20, MgO, CaO, S, CIN and Organic Matter in the residues of the açaí fruit and verify its viability as an organic fertilizer. In the field work, soil, residues of the acai fruit and cacao seeds (Theobroma cacao) were used, outlining entirely randomly 5 treatments with 3 repetitions each. pH, C, P, K, Na, Ca, Mg, AI, exchangeable H + AL, Zn, Mn, S, Fe, B and Cu were analyzed in the soil samples and in the residues of the acai fruit. The residues showed: 0.62% of P205; 0.038% of Ca; 0.099% of Mg; 0.004% of Zn; 0.022% of Mn and 0.018% of Cu. Due to the high content of these elements found in the residues of the açaí fruit, associated with the large amount of material that is discarded during processing, it can be inferred that açaí is one of the responsible for the high levels of Ca, Mg, Zn, Mn, P and C found in APTs. Regarding the use of açaí residues as fertilizer, it was verified that: the testimony showed a better response than the treatments; the soil analysis for fertility showed no significant difference between treatments and the soil sample with tanned residue showed high fertility in relation to the others. Thus, taking into consideration the response of cocoa and soil analysis, we conclude that the residues of the açaí fruit, in order to be used as organic fertilizer, require time to make the chemical elements available to the plants.
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