Effect of Nitrogen Inhibitors on Nitrous Oxide Emissions and Pasture Growth After an Autumn Application in Volcanic Soil Efecto de Inhibidores de Nitrógeno en las Emisiones de óxido Nitroso y Crecimiento de la Pradera después de la Aplicación Oto al en un Suelo Volcánico

A range of technologies is available to reduce greenhouse gas emissions from agricultural systems. Among these, applying N transformation inhibitors is promising in reducing nitrous oxide (N2O) emissions in both arable and pastoral soils. A randomized complete block design with six replicates was used to quantify the effect of urease (UI) and nitrification (NI) inhibitors on N2O emissions and pasture production from permanent pasture in an Andisol after autumn-applied urea. The N2O emissions were measured periodically for 8 wk with PVC stationary chambers. Mineral N, DM yield, N concentration, and N uptake were analyzed. Our results show that adding fertilizer (40 kg N ha-1) significantly increased N2O emissions by 281% over the control treatment (P < 0.05) and adding N inhibitors to fertilizer N resulted in a 10%-29% reduction in emissions. Both inhibitors initially reduced nitrate-N production in the Andisol (Osorno series) either by slowing urea hydrolysis or the nitrification process. Increases in pasture yield (8%-13%), N concentration (7%-9%), and N uptake (46%-56%) were measured by adding N inhibitors with urea. Emission factors, measured under field conditions in Chile after autumn- applied urea and N inhibitors (applied alone or combined), were very low (0.052%-0.114%) compared with values reported in the literature and the Intergovernmental Panel on Climate Change (IPCC) default value (1%). Using these technologies could contribute to Chile's nationally established goal of a 20% reduction in greenhouse gas emissions by 2020. Una gama de tecnologías están disponibles para reducir las emisiones de gases de efecto invernadero desde sistemas agrícolas. Entre éstas, la aplicación de inhibidores de transformación del N es considerada prometedora para reducir emisiones de oxido nitroso (N2O) en suelos de cultivo y praderas. Un dise o de bloques completos al azar con seis repeticiones se utilizó para cuantificar el efecto de inhibidores de ureasa (UI) y nitrificación (NI) sobre emisiones de N2O y producción de pradera permanente sobre un Andisol después de la aplicación oto al de urea. Las emisiones de N2O se midieron periódicamente durante 8 semanas en cámara estacionaria de PVC. Se analizaron N mineral, rendimiento de MS, concentración de N, y absorción de N. Los resultados muestran que la aplicación de fertilizante (40 kg N ha-1) aumentó significativamente las emisiones de N2O en 281% sobre el tratamiento control (P < 0,05) y generó 10-29% de reducción de emisiones. Ambos inhibidores redujeron la producción de N-nitrato en el Andisol serie Osorno p