Forage mass, chemical composition and leaf chlorophyll index of signal grass and organic matter in soil under increasing levels of nitrogen

Abstract

This study evaluated the forage mass, plant height, chemical composition and chlorophyll index of signal grass (Brachiaria decumbens cv. Basilisk), as well as the content of organic matter (OM) in soil under increasing levels of nitrogen. The experiment was conducted in the Rio Manso Farm, experimental unit of the Federal University of the Jequitinhonha and Mucuri Valleys - UFVJM in the municipality of Couto de Magalhães de Minas, state of Minas Gerais. For plant evaluation, we use a split plot randomized block design with four replications. Nitrogen levels (0, 25, 50, 75, 100 kg ha-1 N) were assigned to plots and the cuts made in plants, to subplots. For the assessment of soil organic matter, we used a split-split-plot, with nitrogen levels (0, 25, 50, 75 and 100 kg ha-1 by cut) in the plots, collection depth (0-10 and 10-20 cm) in the subplots and three sampling times (before the onset of the experiment, at the end of the 1st crop year and at the end of the 2nd crop year) in sub-subplots in a randomized block design with four replications. It can be concluded that nitrogen fertilization linearly increases forage mass, plant height and crude protein content of signal grass, which are positively correlated with chlorophyll index. At the end of two agricultural years, the content of organic matter in the soil decreases, which can be attributed to management of cutting and removal of the cut material.