Nitrous oxide emission and fertiliser nitrogen efficiency in a tropical sugarcane cropping system applied with different formulations of urea

Abstract

Abstract. Nitrous oxide (N 2 O) emissions from sugarcane cropped soils are usually high compared with those from other arable lands. Nitrogen-efficient management strategies are needed to mitigate N 2 O emissions from sugarcane farming whilst maintaining productivity and profitability. A year-long field experiment was conducted in wet tropical Australia to assess the efficacy of polymer-coated urea (PCU) and nitrification inhibitor (3,4-dimethylpyrazole phosphate)-coated urea (NICU). Emissions of N 2 O were measured using manual and automatic gas sampling chambers in combination. The nitrogen (N) release from PCU continued for >5-6 months, and lower soil NO 3 -contents were recorded for !3 months in the NICU treatments compared with the conventional urea treatments. The annual cumulative N 2 O emissions were high, amounting to 11.4-18.2 kg N 2 O-N ha -1 . In contrast to findings in most other cropping systems, there were no significant differences in annual N 2 O emissions between treatments with different urea formulations and application rates (0, 100 and 140 kg N ha -1 ). Daily variation in N 2 O emissions at this site was driven predominantly by rainfall. Urea formulations did not significantly affect sugarcane or sugar yield at the same N application rate. Decreasing fertiliser application rate from the recommended 140 kg N ha -1 to 100 kg N ha -1 led to a decrease in sugar yield by 1.3 t ha -1 and 2.2 t ha -1 for the conventional urea and PCU treatments, respectively, but no yield loss occurred for the NICU treatment. Crop N uptake also declined at the reduced N application rate with conventional urea, but not with the PCU and NICU. These results demonstrated that substituting NICU for conventional urea may substantially decrease fertiliser N application from the normal recommended rates whilst causing no yield loss or N deficiency to the crop. Further studies are required to investigate the optimal integrated fertiliser management strategies for sugarcane production, particularly choice of products and application time and rates, in relation to site and seasonal conditions.

Emission factors for estimating fertiliser-induced nitrous oxide emissions from clay soils in Australia’s irrigated cotton industry

“…The magnitude of seasonal N 2 O emissions in response to high N fertiliser inputs in Australian cotton systems is only surpassed by those from sugar cane (Wang et al 2016), even though the latter normally receives significantly lower N inputs compared with cotton. The large amount of fresh residues retained in cane systems reduces evaporative losses and supplies carbon to fuel denitrification on low pH soils, which increases the proportion of N 2 O emitted (Rochester 2003).…”

Respuesta polinómica de la emisión de óxido nitroso en plantaciones de café en Costa Rica

“…El incremento observado en la emisión luego de la aplicación de los fertilizantes coincide con eventos lluviosos, lo cual indica que ambos factores, mayor disponibilidad de nitrógeno en el suelo y el incremento de la humedad del suelo, favorecen la emisión de este gas, tal y como ha sido previamente reportado tanto en café (Hergoualc´h et al, 2008;Montenegro, 2013) como también en otros cultivos (Schwenke y Haigh, 2016;Wang et al, 2016).…”

“…Dicha condición se pudo observar de manera transitoria durante los eventos de fertilización en esta investigación, ya que inmediatamente después de los mismos fue cuando se detectaron los mayores valores de emisión (Figuras 2 y 9), situación que coincidió con eventos de lluvia y en consecuencia, con mayor nivel de humedad en el suelo (Figuras 3 y 10), lo que estimuló la formación y liberación del óxido nitroso. Este contexto ha sido reseñado en diferentes publicaciones científicas (Hergoualc´h et al, 2008;Wang et al, 2016;Zhou et al, 2016) donde se remarca que la interacción de factores tales como la humedad del suelo y temperaturas cálidas en presencia de nitrógeno por la fertilización, conducen a eventos importantes de emisión del gas en mención.…”

Tail‐drain sediments are a potential hotspot for nitrous oxide emissions in furrow‐irrigated Vertisols used to grow cotton: A laboratory incubation study

“…The increased production and emission of greenhouse gases, including nitrous oxide (N 2 O), from the soil is one such direct impact. Land management practices, in conjunction with climate, fertilizer, and water management practices all affect the scale of N 2 O emissions from agricultural soils (Reeves, Wang, Salter, & Halpin, ; Wang et al., ). In recent years, global N 2 O research has focused on mitigating emissions associated with agricultural production systems, and Australia has invested extensively in mitigation research within many dryland and irrigated agricultural industries (Grace, ).…”

“…and water management practices all affect the scale of N 2 O emissions from agricultural soils (Reeves, Wang, Salter, & Halpin, 2016;Wang et al, 2016). In recent years, global N 2 O research has focused on mitigating emissions associated with agricultural production systems, and Australia has invested extensively in mitigation research within many dryland and irrigated agricultural industries (Grace, 2016).…”