Effect of Nitrogen Fertilization on Production, Chemical Composition and Morphogenesis of Guinea Grass in the Humid Tropics

Abstract

The use of nitrogen fertilization in tropical grasslands is a strategy that may reduce the pressure of livestock production on biome areas with humid forests. The objective of this study was to assess the use of different doses of nitrogen in Guinea grass (Megathyrsus maximus (Jacq.) con. Mombasa) cultivated in the humid tropics. Doses of 0, 10, 20, 30, 40, and 50 kg of N ha−1 application−1 were applied during two consecutive years in experimental plots. The experimental area is located in the northeast of Pará, Brazil, with a predominantly tropical climate according to the Köppen classification. The morphogenic, production, and qualitative characteristics of the forage were evaluated. The morphogenic variables, rate of leaf appearance and rate of leaf elongation, in addition to daily accumulation of forage and crude protein content, increased with increasing doses of nitrogen. The morphological structure of the pasture was not modified. The number of cuts increased, whereas the number of days of recovery decreased, in the rainy season with increasing doses of nitrogen. The use of nitrogen fertilization does not alter the structure of the pasture; however, it improves the morphogenic, production, and chemical characteristics of Guinea grass.

Optimum nitrogen fertilization rate and nitrogen use efficiency forBrachiariahybrid andMegathyrsus maximusvaries with stage of regrowth

“…Like the present study, linear and quadratic responses in herbage accumulation in M. maximus with low incremental levels of N fertilization were previously reported. 10 However, this study did not distinguish fertilization response based on stages of maturity. Although…”

“…For example, N fertilization did not affect ADF 6,10 and lignin 10 but caused a linear decline in NDF contents in M. maximus. 10 while both NDF and ADF content in Brachiaria hybrid declined as N fertilizer increased. 27,21 In addition to species differences, stage of maturity seems to also have a major role in cell-wall accumulation in grass forages treated with increasing N fertilizer rates.…”

“…9 Nitrogen fertilization also improves biomass yield and forage intake by ruminants. 10 However, N fertilizer use in pastures has shifted from traditionally high rates of application, 11 to much lower rates. 12,13,10 This shift is driven by the increasing cost of inorganic N fertilizers, environmental concerns associated with excessive N fertilizer use, and scientific evidence that N fertilizer is more efficiently used by pastures when applied at low rates.…”

“…10 However, N fertilizer use in pastures has shifted from traditionally high rates of application, 11 to much lower rates. 12,13,10 This shift is driven by the increasing cost of inorganic N fertilizers, environmental concerns associated with excessive N fertilizer use, and scientific evidence that N fertilizer is more efficiently used by pastures when applied at low rates. 14 It was recently demonstrated that herbage yield and nutritive value of Paspalum atratum harvested after 6 and 12 weeks of regrowth were optimized at 56 and 52.3 kg N ha À1 , respectively.…”

Agrometeorological and Agronomic Characterization of Megathyrsus Grasses Cultivated in Tropical Humid and Semi-Arid Conditions: A Multivariate Approach

“…As for aspects related to the soil, nitrogen (N) is the most important nutrient in tissue flow, and its assimilation may be limited by a water deficit (Onillon et al, 1995). Therefore, when climate conditions are favorable and nitrogen supply is adequate, studies in the literature support that the growth of tropical grasses, especially of the genus Megathyrsus, will be rapid, as there will be an increase in regrowth vigor and a reduction in the interval between grazing (Oliveira et al, 2020).…”