Nitrogen use efficiency and nitrous oxide emissions from five UK fertilised grasslands

Abstract

Intensification of grasslands is necessary to meet the increasing demand of livestock products. The application of nitrogen (N) on grasslands affects the N balance therefore the nitrogen use efficiency (NUE). Emissions of nitrous oxide (N 2 O) are produced due to N fertilisation and low NUE. These emissions depend on the type and rates of N applied. In this study we have compiled data from 5 UK N fertilised grassland sites (Crichton, Drayton, North Wyke, Hillsborough and Pwllpeiran) covering a range of soil types and climates. The experiments evaluated the effect of increasing rates of inorganic N fertiliser provided as ammonium nitrate (AN) or calcium ammonium nitrate (CAN). The following fertiliser strategies were also explored for a rate of 320 kg N ha −1 : using the nitrification inhibitor dicyandiamide (DCD), changing to urea as an N source and splitting fertiliser applications. We measured N 2 O emissions for a full year in each experiment, as well as soil mineral N, climate data, pasture yield and N offtake. N 2 O emissions were greater at Crichton and North Wyke whereas Drayton, Hillsborough and Pwllpeiran had the smallest emissions. The resulting average emission factor (EF) of 1.12% total N applied showed a range of values for all the sites between 0.6 and 2.08%. NUE depended on the site and for an application rate of 320 kg N ha −1 , N surplus was on average higher than 80 kg N ha −1 , which is proposed as a maximum by the EU Nitrogen Expert Panel. N 2 O emissions tended to be lower when urea was applied instead of AN or CAN, and were particularly reduced when using urea with DCD. Finally, correlations between the factors studied showed that total N input was related to Nofftake and Nexcess; while cumulative emissions and EF were related to yield scaled emissions.

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

“…Similarly, short-term responses of FN2O to AN application were also determined by others, e.g. Bouwman et al (2002);Jones et al (2007) and Cardenas et al (2019). However, for our study AN treatment effects on FN2O were of secondary interest.…”

Management Intensity Controls Nitrogen-Use-Efficiency and Flows in Grasslands—A 15N Tracing Experiment

“…Various studies have investigated the impact of warming and management on grassland biomass production [10,22,23], N leaching losses [20,24] and nitrous oxide (N 2 O) emissions [25][26][27][28]. However, little is known on the fates of slurry N in the grassland plant-soil system and how it is partitioned to plant nutrition, storage in soil, total leaching and gaseous N losses.…”

Intensive slurry management and climate change promote nitrogen mining from organic matter-rich montane grassland soils

“…Effects of management (i.e. intensive vs. extensive fertilization with cattle slurry along with high versus low mowing frequency) and climate change on grassland productivity (Berauer et al 2019;Fraser et al 2015;Fu et al 2019;Sebastià et al 2008), associated N exports, N loss pathways such as N leaching (Fu et al 2017;de Vries et al 2012), gross N mineralization rates (Wang et al 2016) and nitrous oxide (N 2 O) emissions (Butterbach-Bahl and Dannenmann 2012; Cantarel et al 2011;Cardenas et al 2019;Wolf et al 2010) are increasingly understood. So far, few studies investigated the N use efficiency of grasslands fertilized with slurry (Hoekstra et al 2010), N fates in the plant-soil system of grasslands (Bardgett et al 2003;Harrison et al 2007Harrison et al , 2008Hart et al 1993;Xu et al 2011), and the overall N balance of grassland soils (Ammann et al 2009).…”