Produção de silagem de milho fertilizado com biossólido: composição bromatológica

Abstract

The objective of this study was to evaluate the use of biosolids as a partial substitute for mineral fertilizer in the culture of corn for silage production on the bromatological composition. The experimental area has a 23-year history of biosolids use. In 1997/98 (implementation), the experiment was set up in randomized block design with 4 treatments and 5 repetitions, totaling 20 plots. In the first year, the treatments used in the installation of the experiment were: T1 = control (without application of biosolid (BI) and without mineral fertilization); T2 = 2.5 t ha-1; T3 = 5 t ha-1, T4 = 10 t ha-1 of BI (dry base). In the second year, the witness started to receive mineral fertilization based on soil analysis and Bulletin 100 indications. From the fourth year on, the dose 2.5 t ha-1 of BI was replaced by 20 t ha-1 with the purpose of increasing the risks of pollution and phytotoxicity. Over the 23 years of experimentation, four crops were used (corn, sunflower, guandu and crotalaria), and the biosolids applied came from three Sewage Treatment Plants (STPs) in the State of São Paulo (Barueri, Monte Alto and Franca). In the 23rd year, the biosolid was obtained from the ETE of Monte Alto/SP, operated by SABESP and corn (VT PRO 2 - silage production) was used as test plant. The harvest point for ensiling was when the majority of the plants presented dry matter of 35%. The forage was ensiled in experimental mini silos and the silos were opened after 150 days of fermentation process. The samples were evaluated for composition of crude protein, neutral detergent fiber, acid detergent fiber, lignin, cellulose, and hemicelluloses. No significant difference was observed between the treatments evaluated on the contents of protein, fiber fraction, lignin and mineral matter of the silages. It was concluded that the use of biosolids as fertilizer in corn culture does not affect the nutritional quality of the silages obtained and can partially replace chemical fertilization