Agronomic and nutritional responses of Carajas elephant grass fertilized with protected and non-protected urea

• Autor(a) principal: Alves, Francisco Gleyson da Silveira
• Data de Publicação: 2018
• Outros Autores: Carneiro, Maria Socorro de Souza, Edvan, Ricardo Loiola, Cândido, Magno José Duarte, Furtado, Rafael Nogueira, Pereira, Elzânia Sales, Morais Neto, Luiz Barreto de, Mota, Rute Ribeiro Marins, Nascimento, Keuven dos Santos
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Semina. Ciências Agrárias (Online)
• Texto Completo: https://ojs.uel.br/revistas/uel/index.php/semagrarias/article/view/31333
• topic: Biomass components; Biomass flow; Bromatology; Pennisetum purpureum × Pennisetum glaucum; Protected urea; Urea.; Bromatologia; Componentes da biomassa; Fluxo de biomassa; Pennisetum purpureum x Pennisetum glaucum; Ureia; Ureia protegida.

The objective of this study was to assess the agronomic and nutritional responses of the elephant grass cultivar Carajas when subjected to fertilization with protected and conventional urea. A randomized block design with 4×2+1 factorial arrangement was adopted. The treatments consisted of four doses (100, 200, 400, and 800 kg N ha-1), two nitrogen sources (conventional and protected urea), and one additional treatment without fertilization. The experiment was carried out from October 2015 to March 2016, in a semi-arid region with a dystrophic yellow latosol type soil. The application of conventional urea was done with each of the multiple cuts performed per year, whereas the protected urea was applied in a single dose. Total senescence rate (TSR), leaf and stem elongation, height, tiller density, total forage biomass, green leaf and stem biomass, and dry matter all increased with increasing N doses. However, the phyllochron, live material/dead material ratio, and agronomic efficiency all decreased with N increasing dose. Plants fertilized with protected urea presented greater TSR and phyllochron. Mineral matter content was higher in plants fertilized with conventional urea. Neutral detergent fiber content was maximized at a dose of 437.63 kg N ha-1. The protected urea resulted in a higher value of leaf/stem ratio at the 400 kg N ha-1 dose, whereas ether extract and crude protein at the 800 kg N ha-1. With application of conventional urea, the highest crude protein value occurred at a dose of 100 kg N ha-1. The morphogenesis, structure, production, and chemical composition of elephant grass ‘Carajas’ were all positively influenced when nitrogen doses were increased, with the recommended optimal dose for use being 400 kg N ha-1 for both sources. The use of protected urea is recommended because of its slow release and need for only a single application.