Production and morphological characteristics of marandu grass under inoculation and levels of nitrogen fertilization

Forage production and quality are influenced by the supply of nitrogen, especially urea, which is highly subject to losses through volatilization. Alternatively, technology that reduces nitrogen release has emerged, restricting losses by coating the fertilizer with polymers. Furthermore, there is a combination of multifunctional soil microorganisms capable of capturing atmospheric nitrogen and making it available to forage plants as a possibility to reduce external dependence on nitrogen. Thus, this study aimed to evaluate seed inoculation and the use of coated urea in the production of shoot and root dry mass, and the morphological characteristics of Marandu grass (Urochloa brizantha cv. Marandu). The experiment conducted in pots was set up in a completely randomized design with four replications in a 5 x 4 x 4 factorial scheme. Five nitrogen fertilization doses (50, 100, 150, 200, and 250 kg N ha(-1)) were applied in a single dose, using the synthetic fertilizer urea. The factors consisted of four techniques: fertilization with urea, fertilization with coated urea, Marandu grass seeds treated with commercial inoculant and fertilization with urea, and Marandu grass seeds treated with commercial inoculant and fertilization with coated urea. The observations (forage canopy height, number of tillers per pot, and shoot forage mass) were obtained every 21 days, totaling four sequential evaluation cuts. Root dry mass was obtained by a single measurement in the fourth cut, arranged in a 5 x 4 factorial scheme, with four replications. The dose of 50 kg N ha(-1), using conventional urea, characterizes economic and environmental provision to Marandu grass canopy height under adequate soil moisture conditions. The nitrogen dose up to 200 kg ha(-1) promotes an increase in the number of tillers, while equal and higher doses ensure maintenance of forage mass production potential for up to 2 cuts. Conventional urea enabled superior root mass production of Marandu grass at nitrogen doses between 150 and 250 kg ha(-1).