Biomass flow and defoliation pattern in alexandergrass fertilized with nitrogen

Abstract

ABSTRACT:The determination of biomass flows can assist on improving pasture fertilization techniques, contributing to identify the best management methods and, in relation the use of fertilizers. Nitrogen deficiency in pastures can reduce forage production. On the other hand, there is an environmental concern on nitrogen (N) losses when this nutrient is used in excess and this concern guides the search for new grazing systems that optimize its use. Leaf biomass flow, intensity and frequency of defoliation were evaluated in Alexandergrass (Urochloa plantaginea (Link) Hitch) fertilized with Zero, 100, 200 or 300 kg/ha nitrogen (N) as urea. The grazing method was put and take stocking in order to keep the forage mass at 3,000 kg/ha DM. The experimental animals were Angus heifers with an initial age of 15 months and body weight of 241.5±5 kg. The experimental design was completely randomized following a repeated measure arrangement, with four treatments and variable number of experimental units. The highest growth of leaf blades was achieved with 100 kg/ha N. Senescence and intake flows and defoliation intensity were similar among the N levels used. The frequency of return to the same tiller (days) was influenced by N levels and evaluation periods. Our findings recommend the use of 100 kg/ha N in Alexandergrass pasture.

Nitrogen nutrition index and morphogenesis in Alexandergrass of the Central Depression of Rio Grande do Sul

“…The absence of N levels effect on leaf and stem expansion rates is not the usually reported answer when studies involve these two factors. These responses showed that, generally, as the nitrogen fertilization increase, a higher expansion rate of these components is observed (HUNDERTMARCK et al, 2017;TIECHER et al, 2017). Observations showed; however, a similar rate of leaves and stems expansion in the absence or presence of N fertilization.…”

“…The leaf expansion rate reduction of 0.000028 cm degree-days -1 per accumulated degreeday can be explained by Alexandergrass being a tropical climate species, which response to the temperature lowering and reduced daily light is the reduced leaf expansion (HUNDERTMARCK et al, 2017). Also, the approximation of the reproductive stage of Alexandergrass may have provided a greater nutrients allocation to the reproductive organs, in detriment of the leaf blades production.…”

“…Studies with nitrogen fertilization in Alexandergrass (Urochloa plantaginea (Link) Hitch) have been carried out in the southern region of Brazil (SARTOR et al, 2014;SALVADOR et al, 2016;HUNDERTMARCK et al, 2017). However, the literature shows no data about the hypothesis that the morphogenic response of this grass may be altered by the use of N. The understanding of these relationships, in the context of individual tillers, can provide more detailed information and support decisions on the management of N fertilization.…”

Dynamics of forage production in annual ryegrass cultivars / Dinâmica da produção de forragem de cultivares de azevém anual

“…The basic unit of a forage plant is the tiller (HODGSON, 1990) which originate from the buds, which originates from the shoots, which are correlated with the rate of leaf appearance, are also influenced by interaction of various factors, such as light, temperature and nutrients in the soil, nitrogen availability can directly alter the tillering potential and have a direct link with leaf production (HUNDERTMARCK et al, 2017).…”

Frequência de desfolhação e nitrogênio como determinantes do perfilhamento e do acúmulo de forragem do capim BRS Zuri sob lotação rotativa

“…A produção e o acúmulo de forragem são determinados pelo processo dinâmico do surgimento, sobrevivência e morte dos perfilhos (Giacomini et al, 2009;Sousa et al ., 2019). O perfilhamento pode ser afetado por diversos fatores como temperatura, luz, água, estádio de desenvolvimento, macro e micronutrientes no solo, principalmente o nitrogênio (Langer, 1979;Hundertmarck et al, 2017). Compreender a dinâmica do perfilhamento torna-se essencial para definir práticas de manejo que garantam a produtividade, sustentabilidade e longevidade da pastagem ao longo do período produtivo (Sousa et al, 2019).…”