Forage characterization of Carajás grass (<i>Cenchrus purpureus</i> × <i>C. americanus</i>) fertilized with a range of doses of protected urea under irrigation during the growing season

Abstract

The objective of this study was to assess the agronomic and nutritional responses of Carajás grass (Cenchrus purpureus × C. americanus, syn. Pennisetum purpureum × P. glaucum, cultivar ‘Carajás’) fertilized with protected urea. The experimental design was completely randomized blocks in split-plot arrangement over time. The treatments consisted of 5 levels of nitrogen (0, 100, 200, 400 and 800 kg N/ha/year) and measurements were made over 2 seasons (spring 2015 and summer 2016), with 8 replicates. Leaf and stem elongation and senescence rate of tillers increased as N dosage increased, while tiller density, leaf:stem ratio, live:dead material ratio and phyllochron declined. Forage biomass increased with N dosage reaching 47 t DM green forage/ha at 800 kg N/ha but DM production per unit of N applied declined dramatically as level of N applied increased. There was no effect of season. For crude protein (CP) and fiber concentrations, a positive effect was observed with increasing N application, with maximum CP% of 172 g/kg with 800 kg N/ha in spring. Further studies are warranted to determine if economics indicate that the higher fertilizer levels are justified and even protected urea should still be applied on a number of occasions, but still less often than conventional urea, rather than as a single dose at the beginning of spring.

Morphological and Productive Characteristics and Chemical Composition of Grasses in Degraded Areas Subjected to Pasture Recovery Methods

“…The average number of tillers per plant of the genus Brachiaria in this study was similar to the results of previous studies (184 tillers), showing that, even under a certain degree of degradation, there were equivalent numbers of tillers to areas of pasture with productive vigor [2]. Unlike the other grasses studied, Marandu grass was not responsive to recovery methods, presenting a decrease in the number of tillers.…”

“…The experiment was carried out at the Experimental Farm Alvorada do Gurguéia which is located in the Professora Cinobelina Elvas Campus of the Federal University of Piauí, in Alvorada do Gurguéia, Piaui, Brazil. According to Köppen the region has a tropical climate with summer rains [6] and two well-defined seasons: the dry season, which extends from May to October, and the rainy season, which extends from November to April (Figure 1), with geographic coordinates 8 from the continuous emission of tillers [2], which is a process that maintains the continuation and formation of pastures after animal grazing [3].…”

“…The forage yield and nutritional quality of grasses are guaranteed by the adequate management of pasture (maintenance fertilization) so that the nutritional needs demanded by the animals can be met, allowing at the same time the persistence and production of roughage. The amount of biomass of forage plants results in their growth from the continuous emission of tillers [2], which is a process that maintains the continuation and formation of pastures after animal grazing [3].…”