Nitrogen recovery and loss in a fertilized elephant grass pasture

Abstract

Limited information is available regarding the recovery and loss of fertilizer nitrogen (N) applied to intensively managed tropical grass pastures. An experiment was carried out in Brazil to determine the fertilizer-N recovery and ammonia volatilization loss in an elephant grass (Pennisetum purpureum, Schum.) pasture fertilized with 100 kg N ha )1 as urea or ammonium sulphate, labelled with 15 N, in late summer (LS) or in midautumn (MA). Herbage mass was highest and litter mass was lowest in LS (P < 0AE05). The N concentration of herbage was highest in autumn (P < 0AE05) and the total N content in soil was lower in LS than in MA (P < 0AE05), reflecting the high N uptake capacity of the grass. Proportionately higher 15 N recovery in litter mass (P < 0AE05) was observed in autumn (0AE094) than in LS (0AE0397) and the 15 N recovery in herbage was 0AE046 higher for ammonium sulphate-fertilized pastures (P < 0AE05; proportionately 0AE243 for ammonium sulphate and 0AE197 for urea). Around 0AE60 of the fertilizer-15 N recovered was retained in soil and in non-harvestable fractions of the plant. The NH 3 volatilization loss was higher in LS and most of the N loss occurred soon after fertilizer application. Urea and ammonium sulphate fertilizers were equally effective in sustaining herbage dry matter yield in the short term. However, the use of ammonium sulphate, rather than urea, would be preferable for LS applications when the objective is to reduce NH 3 volatilization losses.

Forage legumes in grass pastures in tropical Brazil and likely impacts on greenhouse gas emissions: A review

“…As a global mean, 0.9% of the added fertilizer N is considered to be directly transformed into N 2 O (Bouwman, Bouwman, & Batjes, 2002), a value that was close to that found for an Oxisol under Marandu grass in Central Brazil, but somewhat above the average of 0.5% measured in similar pastures fertilized with urea on a coarser soil of the Brazilian tableland coast (Table 1). In addition, the application of urea to the soil surface or litter layer can favour ammonia volatilization that may lead to losses exceeding 30% of the added N (de Morais et al., 2013; Martha, Corsi, Trivelin, & Alves, 2004). Emissions of N 2 O from the deposition of the volatilized N are considered to follow the same process of any N source and considered to be equivalent to 1% of the N lost (IPCC, 2006).…”

Regeneration of fertile, hexaploid, interspecific hybrids of elephantgrass and pearl millet following treatment of embryogenic calli with antimitotic agents

“…is one of the most productive biomass plants in tropical and subtropical climates and it is an important forage and bioenergy crop (Martha et al 2004;Strezov et al 2008). Its relative, pearl millet (Pennisetum glaucum (L.), grows well on soils with low fertility, is drought tolerant and produces a high biomass quality (Serraj et al 2005).…”

Recuperação de 15N-ureia no sistema solo-planta de pastagem de capim-tanzânia

“…Todavia, até o momento, poucos experimentos de campo foram realizados com gramíneas tropicais e fertilizante-15 N (Harper et al, 1983;Impithuksa et al, 1984;Impithuksa & Blue, 1985;Oliveira et al, 2003;Martha Jr. et al, 2004a). Ademais, ainda não há estudos com fertilizante-15 N em pastagem de P. maximum cv.…”