Strategies that improve the use of nitrogen (N), by tropical forage grasses, can bring environmental and social gains. Thus, this study aimed to evaluate the forage productivity and the nutritional value (NV) of the hybrid Urochloa spp. cv. ´Mavuno`, under inoculation with plant growth-promoting bacteria (PGPB) and doses of N. The experiment was carried out in the field, for a period of 14 months, in a randomized block design, with nine treatments and four replications in plots of 9 m². Seed inoculations were tested with: Azospirillum brasilense Ab-V5 and Ab-V6 strains; Pseudomonas fluorescens CCTB 03 and co-inoculation with Rhizobium tropici CIAT 899 and A. brasilense Ab-V6, combined with 50 and 100 kg ha-1 of added mineral N; fertilization with N-mineral with these doses, without inoculation and the control treatment, without N and without inoculation. The bacteria were inoculated to the grass seeds. The forage was evaluated by determining the shoot dry weight yield (SDWY) and the levels of crude protein (CP), neutral detergent insoluble fiber (NDF), acid detergent insoluble fiber (ADF) and in vitro dry matter digestibility (IVDMD). The results were subjected to analysis of variance by the F test (p ≤ 0.05) and compared to each other by the Scott-Knott test at 5% probability. Inoculation with PGPB resulted in greater SDWY when associated with a dose of 50 kg ha-1 of N. In plants inoculated with A. brasilense Ab-V5 + Ab-V6 and P. fluorescens CCTB 03, associated with a dose of 50 kg ha-1 of N-mineral, SDWY was similar to that obtained with double the dose of N in the absence of inoculation. The inoculation with PGPB resulted in an increase in the NV of Mavuno grass, with emphasis on A. brasilense Ab-V5 + Ab-V6 and P. fluorescens CCTB 03, associated with the dose of 100 kg ha-1 of N-mineral that improved the nutritional value in all evaluated items. The inoculation with A. brasilense Ab-V5 + Ab-V6 was the most promising, followed by P. fluorescens CCTB 03, mainly in association with 50 kg ha-1 of N.

The objective of this study was to evaluate the effects of plant growth-promoting bacteria (PGPB) strains of Azospirillum brasilense, Pseudomonas fluorescens and Rhizobium tropici on biomass yield, number of tillers, nitrogen accumulation and nutritive value of shoots of Megathyrsus (syn. Panicum) maximus cultivar BRS Zuri (Zuri Guinea grass). For that, one experiment was performed for 14 months to evaluate inoculation and re-inoculation with Azospirillum brasilense strains Ab-V5 and Ab-V6, Pseudomonas fluorescens strain CCTB 03 and of co-inoculation with Rhizobium tropici strain CIAT 899 + A. brasilense strain Ab-V6 combined with N-fertilizer (100 kg of N ha-1). Shoot dry weight yield (SDWY), number of tillers (NT), total N concentration (TNC), total N uptake (TNU) and nutritive value of Zuri Guinea grass was evaluated for eight cuts, and inoculation increased all parameters. In the NT, the treatments inoculated with PGPB were superior to the positive non-inoculated control receiving N-fertilizer, by up to 36%. For the accumulated of SDWY the treatment re-inoculated with P. fluorescens CCTB 03 after each cut was statistically superior tin 7% the positive control. The PGPB when combined N-fertilizer also increased SDWY, NT, the relative chlorophyll index, TNC, total N uptake, neutral detergent fiber, acid detergent fiber, crude protein and in vitro digestibility dry matter of Zuri Guinea grass. The results indicate that PGPB can represent a sustainable alternative for reducing the use of N-fertilizers. The lower effects of re-inoculation with PGPB on the nutrition or yield of Zuri Guinea grass, demonstrating that the determination of the method of application and periodicity of inoculation still require investigation.

Confinement of dairy cows in Brazil is significant, with the compost badded pack barn being the most used model, generating a large amount of good quality organic compost that can be used as a fertilizer in the pastures of the farms, reducing the use of industrialized fertilizers and mitigating the environmental impacts of dairy activity. An experiment was carried out in pots under greenhouse conditions to evaluate the effect of compost doses on the production, morphology and chemical-bromatological characteristics of Urochloa brizantha cv. Marandu A completely randomized design with 3 replications and 6 treatments consisting of 6 doses of the compost: 0; 50; 10; 20; 40 and 80 g.vaso-1. Increasing compost doses resulted in higher dry matter yield, higher tillers density and higher potassium and phosphorus contents in the forage. Dairy cow compost can be used for pasture fertilization, partially replacing industrialized fertilizers.