Infield N2O emissions in sheep grazing systems

Abstract

The livestock production contributes to around 18% of total anthropogenic greenhouse gases emissions (GHG), and 80% of the agriculture sector. Nitrous oxide (N2O) from manure deposited in grassland is one of the main sources, corresponding to 17% of the livestock sector. Nitrification inhibitors (NI) added to manure and to N fertilizer is a strategy to reduce N2O emissions. However, the N2O emissions as well as the efficiency of the NI can show high variability due different climatic conditions, N sources, and soil types, which is not fully understand. The proposed visiting undergraduate scholarship will be hosted by Bangor University, under the supervision of Professor Dave Chadwick. The proposal includes providing technical assistance in two field experiment and meta-analysis and graphics performance using Sigma Plot Version 1. The activities will be executed in the five weeks between 15 July and 15 August 2019.The present proposal BEPE will include technical assistance in two field experiments. One of the experiments will be conducted by a current UK PhD student at Bangor University with the supervisor of Professor Dave Chadwick. This experiment will determine direct N2O EFs for urine and dung from sheep grazing lowland and upland pastures. Efficacy of the nitrification inhibitor will also be evaluated. In the same study, measurements of enteric methane from sheep grazing lowland and upland pastures will be made using a Greenfeed methane measurement system. During one month visit, will be done assistance in the collection of urine and dung from sheep grazing the lowland pasture, and setting up the urine and dung N2O emission measurements (using static chambers) after 'deposition' to the soil. Technical assistance will be provide with the ruminant methane emissions from the grazing sheep using the Greenfeed system in the lowland pasture. The other experiment that will be assisted, involves the assessment of GHG emissions and nitrate leaching from urine applied to soil in lysimeters taken from different pastures on the altitudinal transect at Bangor University farm (from upland to lowland). The gas samplings will be collect three times per week in the mornings with plastic syringes (60 mL) at three time intervals (1, 15, and 30 min) after the chambers are closed The samples will be transferred and stored in pre-evacuated Exetainers vials (12 mL) prior to analysis on a gas chromatograph with an electron capture detector for N2O determination. Both experiments will generate data to assess the representivity of the current excretal (pasture, range and paddock) EFs used in the UK agriculture greenhouse gas inventory. (AU)