Yield and chemical composition of massai grass fertilized with nitrogen

Marcos Neves Lopes

doi:10.7764/ijanr.v47i2.2068

Abstract

Nitrogen fertilization, in addition to increasing biomass production, can also positively influence the chemical composition of a forage plant. The aim of this research was to evaluate the yield and chemical composition of Megathyrsus maximus cv. Massai grass under five nitrogen fertilization levels (0, 150, 300, 450 and 600 mg N dm -3 soil, equivalent to 0, 300, 600, 900 and 1,200 kg ha -1 year -1 , respectively) and during growth cycles (establishment and regrowth cycles) in a greenhouse. A completely randomized design with split-plot arrangement was adopted in which the five nitrogen levels were the plots and the cycles were the subplots. The total forage biomass increased with the nitrogen fertilization levels in the three growth cycles (28.4 g pot -1 , 32.0 g pot -1 and 29.8 g pot -1 for establishment, regrowth 1 and regrowth 2, respectively, at the level of 600 mg N dm -3 ), and it was reduced from establishment to regrowth at lower N levels. The dry matter content was not affected by the N levels. However, this content presented higher values at the regrowth cycle in comparison to the establishment cycle. The crude protein (CP) content increased (7.0% CP at the level of 600 mg N dm -3 ), while the neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose (HEM) contents all decreased at higher N levels, with the highest CP content being observed at the establishment, and the opposite occurring for NDF, ADF and HEM. Nitrogen fertilization provides positive responses on yield and chemical composition of massai grass.

Highlights

The need to intensify grazing production systems has increased the demand for studies on forage cultivars and their responses to intensive management
The positive effect of nitrogen on the crude protein (CP) content of forage plants can be verified in the studies conducted by Andrade et al (2003) and Rodrigues et al (2005) in which the CP content of the forages increased with the increase of the nitrogen fertilization
The influence of nitrogen on total forage biomass yield (TFB) in massai grass can be attributed to the increase in the leaf appearance rate (Martuscello et al, 2005) and the effect of nitrogen on the leaf elongation rate (Martuscello et al, 2006; Lopes et al, 2013), which can be especially attributed to the increase in cell production (Volenec & Nelson, 1984) and to the influence of nitrogen on physiological processes of the plant (Fagundes et al, 2005), which contributes to the growth and development of the forage plant

Summary

Introduction

The need to intensify grazing production systems has increased the demand for studies on forage cultivars and their responses to intensive management. Nitrogen stands out in forage production (Fagundes et al, 2006) as it provides an increase in tillering (Alexandrino et al, 2004) and in forage biomass production (Magalhães et al, 2006). The positive effect of nitrogen on the crude protein (CP) content of forage plants can be verified in the studies conducted by Andrade et al (2003) and Rodrigues et al (2005) in which the CP content of the forages increased with the increase of the nitrogen fertilization. Nitrogen fertilization may lead to a decrease in the neutral detergent fiber (NDF) content (Vitor et al, 2009; Mota et al, 2010), contradictory responses, such as positive responses of the NDF content to the nitrogen application, have been verified in the literature (Rocha et al, 2002)

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