Produção e qualidade de silagem de sorgo forrageiro inoculado com Azospirillum brasilense e doses de nitrogênio.

Abstract

The objective was to evaluate agronomic and bromatological characteristics of forage sorghum silage inoculated with Azospirillum brasilense bacteria associated with nitrogen fertilization. A randomized block design was used, in a 5x2 factorial arrangement, consisting of five nitrogen doses (0; 50; 100; 200; 400 kg ha-10) with or without A. brasilense, with four replicates. Plant height (PL), stem diameter (SD), first cycle productivity (FCD); regrowth yield (RV), total yield (TV) of forage sorghum; the terrors of dry matter (DM), ash, 0crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), total digestible nutrients (TDN), 0in vitro digestibility (IVDMS), in vitro digestibility neutral detergent fiber (IVDNDF); ammonia nitrogen (N-NH3), organic acids (lactate, acetic acid and butyric acid) and pH values of forage sorghum silages with different treatments. Nitrogen fertilization influenced (P<0.05) PL and SD, PL being higher at the dose of 200 kg ha-1 of N and from the dose of 50 kg ha-1 of N onwards, there was a higher SD of sorghum plants. Interaction between inoculation and nitrogen fertilization was observed for FCD, and nitrogen doses of 200 and 400 kg ha-1 of N showed lower values with inoculation, being 15.66 and 12.44 kg ha-1, respectively. The sorghum TV was lower with the inoculation and higher at the dose of 200 kg ha-1 of N, being approximately 29.42% higher compared to the control treatment. The CP content showed an isolated effect of the inoculation and nitrogen fertilization, increasing the CP contents, being 7.67% with inoculant and 7.01% without the use of inoculant (7.01%). Regarding nitrogen fertilization, doses of 200 and 400 kg ha-1 of N provided higher CP contents, being 8.39% and 9.19%, respectively. There was an isolated effect of nitrogen fertilization on IVDMD. No effects were observed for IVDNDF and TDN. The use of inoculation with A. brasilense does not favor increases in the agronomic characteristics of forage sorghum and reduces productivity at nitrogen rates of 200 and 400 kg ha-1. However, the association does not influence the main fermentative characteristics of sorghum silage. Inoculation with A. brasilense and nitrogen fertilization increases the protein and fiber contents of sorghum silage. The use of the inoculant with A. brasilense in the treatment of AGRI 002E sorghum seeds is not recommended. The dose of 100 kg ha-1 of N can be recommended for cultivation.