Forage accumulation and canopy structure of deferred marandu grass fertilized with nitrogen

Abstract

Nitrogen fertilization of deferred pastures increases the production of forage that will be used in winter, which benefits cattle farmers. The objective of this study was to evaluate the forage accumulation and canopy structure of Brachiaria brizantha cv. Marandu (marandu grass) during the deferment period in response to nitrogen fertilization. Two fertilization strategies of marandu grass were evaluated: fertilization with 200 kg N/ha divided into three applications at intervals of 30 days (two applications before and one at the beginning of the deferment period), and fertilization with a single dose of 50 kg N/ha at the beginning of the deferment period. A completely randomized design consisting of two treatments and four replicates was used. At the beginning of the deferment period, the structural characteristics of the marandu canopy did not differ between nitrogen doses. During the deferment period, the production of forage (P=0.0388), green leaf blade (P=0.0041) and green stem (P=0.0095) was higher for plants fertilized with 200 kg N/ha compared to those fertilized with 50 kg N/ha. The nitrogen doses did not influence leaf blade or stem senescence, with mean values of 1,497 and 1,432 kg dry matter/ha, respectively. Higher (P=0.0265) forage accumulation was observed for marandu grass fertilized with 200 kg N/ha and predominantly occurred in the stem. At the end of the deferment period, plants fertilized with 200 kg N/ha exhibited a greater forage mass (P=0.04), plant height (P=0.0252), extended plant height (P=0.0488), and leaf area index (P=0.0098) than plants fertilized with 50 kg N/ha. The opposite was observed for the percentage of dead stem. The application of a high nitrogen dose results in taller marandu grass with a higher forage mass and percentage of green stem and a lower percentage of dead tissues.

Keywords

• Brachiaria brizantha
• composição morfológica
• massa de forragem.