The leather industry produces a large quantity of solid waste (wet blue leather), which contains a high amount of chromium. After its removal from wet blue leather, a solid collagenic material is recovered, containing high nitrogen levels, which can be used as a nitrogen source in agriculture. In order to take more advantage of the collagen, it was enriched with mineral P and K in order to produce NPK formulations. The objective was also to evaluate the efficiency of such formulations as a nutrient supply for rice plants in an Oxisoil. under greenhouse conditions. The application of PK enriched-collagen formulations resulted in N contents in the vegetative parts and grains of rice plants which were equivalent or superior to those obtained with urea and commercial NPK formulations. (C) 2010 Elsevier B.V. All rights reserved.