Produção e valor nutritivo de forragem de Tifton 85 inoculada com Azospirillum brasilense

Abstract

The use of inoculation with Azospirillum brasilense can make forage systems more efficient, reducing the dependence on nitrogen fertilizer. Most of the Azospirillum-plant association studies have been conducted on cereals and annual grasses, especially. More studies with perennial pastures such as bermudagrass (Cynodon dactylon (L.) Pers.) that require a lot of fertilization to show their production potential are needed. In this sense, the production, nutritional value of forages and the response of pasture and animals in were evaluated based on Tifton 85 bermudagrass in association with ryegrass (Lolium multiflorum Lam.), cv. BRS Ponteio, inoculated with A. brasilense and fertilized with doses of nitrogen fertilizer, grazed by lactating cows. Three forage systems were evaluated: (i) Tifton 85 + A. brasilense + 170 kg N ha-¹ year-¹; (ii) Tifton 85 + 190 kg N ha-¹ year-¹ and (iii) Tifton 85 + 240 kg N ha-¹ year-¹.The experimental design was completely randomized, with three treatments (forage systems), three replications (paddocks) and repeated measures in time (averages of grazing cycles per season). Forage samples were collected before and after grazing to assess plant and animal responses. The inoculation of A. brasilense in pasture, based on Tifton 85 bermudagrass, mixed with ryegrass (in winter and spring), demonstrates a positive effect when equivalent to pasture fertilized with 190 kg of N ha-¹, in the response of plants and animals. Forage yields were 28.6; 29.1 and 32.4 t MS ha-¹, respectively. The results demonstrate that the use of inoculation contributes to improve forage systems and reduce the use of nitrogen fertilizers.