Effect of Nitrogen Inhibitors on Nitrous Oxide Emissions and Pasture Growth After an Autumn Application in Volcanic Soil

Abstract

A range of technologies is available to reduce greenhouse gas emissionsfrom agricultural systems. Among these, applying N transformationinhibitors is promising in reducing nitrous oxide (N2O) emissions inboth arable and pastoral soils. A randomized complete block design withsix replicates was used to quantify the effect of urease (UI) andnitrification (NI) inhibitors on N2O emissions and pasture productionfrom permanent pasture in an Andisol after autumn-applied urea. The N2Oemissions were measured periodically for 8 wk with PVC stationarychambers. Mineral N, DM yield, N concentration, and N uptake wereanalyzed. Our results show that adding fertilizer (40 kg N ha(-1))significantly increased N2O emissions by 281% over the controltreatment (P < 0.05) and adding N inhibitors to fertilizer N resulted ina 10%-29% reduction in emissions. Both inhibitors initially reducednitrate-N production in the Andisol (Osorno series) either by slowingurea hydrolysis or the nitrification process. Increases in pasture yield(8%-13%), N concentration (7%-9%), and N uptake (46%-56%) weremeasured by adding N inhibitors with urea. Emission factors, measuredunder field conditions in Chile after autumn-applied urea and Ninhibitors (applied alone or combined), were very low (0.052%-0.114%)compared with values reported in the literature and theIntergovernmental Panel on Climate Change (IPCC) default value (1%).Using these technologies could contribute to Chile's nationallyestablished goal of a 20% reduction in greenhouse gas emissions by2020.