Evaluation of a Waste from a Brazilian Siderurgy Industry as Alternative for Soil Acidity Correction.

This work evaluated the utilization of a waste from a Brazilian siderurgy industry as alternative for soil liming. It was tested an industrial waste mixture (80 % Total Neutralization Power, 34 % CaO and 16 % MgO) as input for soil pH correction using a commercial limestone (TNP = 80 %; CaO = 30 %; MgO = 12,1 %) and a mixture of gypsum plus CaCO₃ (TNP = 100 %;  CaO = 56 dag/kg) as reference. Lettuce was grown in a clayey distrofic Yellow-Red Latosol (Oxisol) with four doses of each material, calculated based on the soil characteristics and defined as: dose 1 = no material; dose 2 = ½ of the recommended dose; dose 3 = the recommended dose based on the soil analysis; dose 4 = 3 times the recommended dose. The doses in t/ha were: 0.0, 4.2, 8.4, and 12.6 for the waste mixture and for the commercial lime, and (0.0 + 0.0), (1.7 + 3.4), (3.4 + 6.0), and (4.1 + 10.2) t/ha for the gypsum mixture (gypsum + CaCO3). Plants were grown in PVC recipients (15 cm diameter, 60 cm height), treatments applied only in the 20 cm surface layer. Dry matter (DM) yield increased as the corrective doses increased, the regression analysis showed a quadractic response to the treatments. The contrasts showed no diference between the DM production among the treatments indicating that the waste, the comercial lime and the mixture had the same efficiency for soil acidity correction. The regression analysis showed 10.6 t/ha of waste for maximum physical production (23.85 g DM) and 2.36 t/ha of commercial lime for maximum physical production (23.32 g DM). For the gypsum + CaCO3 mixture the doses to get the maximum physical production were 4.30 t/ha and 8.76 t/ha, respectively, to produce 23.38 g DM respectively.