Grazing behaviour, urine composition and soil properties are key controls of N2O emission factors in the uplands

Lead Research Organisation: Rothamsted Research
Department Name: Sustainable Agriculture Sciences-NW

Abstract

The aim of this project is to develop an improved understanding of the spatial and temporal interactions between grazing behaviour, forage selection, urine composition and edaphic conditions and to use the insights garnered to improve the accuracy of nitrous oxide (N2O) emission estimates from contrasting semi-improved and unimproved upland grazed pastures in the UK. This is of major importance because (1) urine patches are a significant source of N2O; ca. 19% of the total N2O losses from agriculture, and (2) N2O losses from upland systems are highly uncertain. Current methods of estimating emissions from urine patches ignore the effect that livestock diet, soil type, soil physico-chemical properties and climate have on N2O fluxes. For example, urine N content varies with protein intake, and the metabolic product in the urine (known to affect N2O production) is affected by what livestock graze. Vegetation in different upland areas varies enormously, with diet selection operating in both systems. Hence it is important to link urine composition to animal movement and diet selection.
Soils in the uplands are dominated by peats and podzols with high carbon content and low pH, influenced by cool, wet climates and topography. These factors will also exert systematic controls on rates of N2O fluxes which are likely to be exacerbated following urine deposition. Moreover, the vegetation in different upland areas influences stocking densities and the consequent potential for urine patch overlap, resulting in disproportionate N2O emissions in areas receiving high N loading rates. Soil in these areas can become compacted due to livestock trampling, reducing air filled pore space, increasing anaerobicity and enhancing conditions for N2O losses via denitrification. It is, therefore, essential to establish the relationships between urine composition (the result of grazing preference), soil type, soil physico-chemical properties (which might be influenced by topographic effects on hydrology) and climate in order to generate improved N2O flux estimates, emission factors and carbon footprints from livestock production.
We will address these knowledge gaps through a combination of:
i) Fine-scale mapping of 'static' factors controlling N2O fluxes, i.e. topography, soil type, vegetation type and soil compaction, using high resolution remotely sensed imaging over contrasting upland areas
ii) Mapping of the 'mobile' factors controlling N2O fluxes, i.e. measuring livestock movement and grazing patterns in these two grassland systems using GPS collars, and observing urination events
iii) Collection of urine from sheep grazing dominant vegetation types and relating the urine composition to dietary preference
iv) Measurement of N2O fluxes following the application of collected urine to soil under typical vegetation types, and calculation of robust urine direct N2O emission factors over a 12 month period
v) Conducting controlled replicated experiments to explore the factors controlling N2O fluxes from soil from contrasting field sites (e.g. changing urine composition, water content and levels of compaction)
vi) Developing a novel model framework to predict the statistics of animal occupancy and to integrate predicted urine emissions with spatial and temporal information of landscape-scale explanatory factors in order to quantify aggregate N2O emissions for upland pastures
Uniquely, we will gain improved understanding of the spatial and temporal interactions between grazing patterns, forage choice, urine composition, soil and climate factors and N2O fluxes in upland systems. Outputs from the project will be compared with IPCC Tier 1 and Tier 2 approaches for estimating N2O emissions from livestock grazing in the UK and provide the basis for robust and scientifically defensible alterations to standard inventory approaches, if required, along with inputs to carbon footprinting and to the spatial targeting of mitigation practices.

Planned Impact

The outputs of this research will impact on society and the economy by influencing the:
SCIENTIFIC COMMUNITY: Our research will inform scientists working in several areas of research e.g. livestock behaviour, grazing management, ruminant nutrition, GHG emissions and modelling. The unique synthesis of the information generated by this project bridges the gap between research which focusses on dietary preference, food production and nutrient/energy balances, and research which focusses on quantifying the impact of soil amendments on N2O emissions from soils. It will link dietary preferences to soil function in contrasting grassland upland pastures using monitoring and observation, mapping, field and laboratory based measurements, all synthesised in a spatially explicit model.
The project strengthens existing research links on GHG emissions and mitigation between Bangor and RRes-North Wyke, and initiates a new collaboration with Cranfield and Leicester Universities in highly complementary disciplines. Chadwick represents the UK in the Livestock Research Group of the Global Research Alliance on Agricultural GHGs. He also leads the UK GHG Platform project to Improve the Agricultural Greenhouse Gas Inventory for Nitrous oxide (http://www.ghgplatform.org.uk/). Cardenas is responsible for the collation and submission of the UK Agriculture GHG inventory. She is also part of the consortium project to deliver the new Tier 2 GHG inventory for agriculture. Perotto-Baldivieso has worked with GPS collars and spatial analysis in the Caribbean and the United States. He has been the president of the International Affairs Committee for the Society for Range Management (2008-2009). We will raise awareness of this project through these networks, and demonstrate the importance of moving to a more sophisticated approach to reflect the effect of dietary preference on direct N2O emissions.
Participation at International conferences will help communicate results and generate interest for future work. The Nitrogen Workshop (in2016/7) attracts researchers mostly from Europe on all aspects of nitrogen cycling, whilst the International Greenhouse Gases and Animal Agriculture Conference in Melbourne (2016) represent a tremendous opportunity to discuss initial research findings and project goals with researchers from outside Europe.
POLICY COMMUNITY: Results from monitoring of livestock movement at the field and landscape scale, offers the opportunity to explore where targeted mitigation strategies could be cost-effective, e.g. through the use of inhibitors to reduce N2O emissions from hot-spots, or through the frequent moving of feeders. Results could prove N2O emission factors (EFs) from urine to be much lower/larger than the IPCC value due to interactions of urine composition, soil properties and climate, with important policy implications re: improving national inventories.
As part of the GHG Platform, Chadwick and Cardenas are regularly invited to give oral presentations to various audiences; policy makers, farmers and industry, providing opportunities to communicate the findings of this project.
INDUSTRY: Research findings will be communicated to the livestock industry, which has set its own targets for GHG mitigation. Our results will be of interest to them, from an EF point of view, but also in terms of development of mitigation strategies, and in the carbon foot printing of their products for comparison with competing countries, such as New Zealand lamb.
WIDER COMMUNITY: A web page on the Bangor website will provide information on the project and its results. Different aspects of the project will be used for teaching at Bangor, Cranfield and Leicester, generating student projects, and will be presented at annual 'tours' of experiments at RRes-North Wyke and Bangor. We will also feature the project in School Science Week, using visualisation of animal 'movement's to stimulate wider discussion about livestock production and the environment.

Publications

10 25 50
 
Description Experiments have been conducted to investigate: the impact of freeze-drying on sheep urine (in terms of its composition and gas emissions from affected soil); the interactive effects of five factors (at two, three or four levels) on the nitrous oxide emissions from upland sheep urine-amended upland soils; and the controls on emissions from acidic upland soils. Key findings are as follows: preliminary analysis indicates that freeze-drying and rehydration of sheep urine does not affect gas emissions (carob dioxide, nitrous oxide or nitric oxide) from soils amended with this urine; and soil moisture is the most important factor controlling nitrous oxide emissions from urine-affected upland soils. Significant achievements include: the scale and detail of laboratory incubation experiments conducted using the state-of-the-art Denitrification Incubation System (DENIS); the collaborative relationships developed; and the volume and quality of lab-based training received and delivered by project members during the project. All key objectives in terms of the work planned for this work package were met, but publication of results is ongoing, as is integration of results into modelling activities. The findings add much needed information about greenhouse gas emissions (particularly nitrous oxide) from upland soils, which were previously less-well studied. In addition, emissions from sheep urine patches are less studied than those from cattle. Finally, studies investigating the interactive/combined effects of many factors (described in more detail below) at once on soil greenhouse gas emissions are sparse and such interactions could produce considerably different results from those investigating single factors.

A fractional factorial experiment design has been used to investigate the interactive effects of factors affecting sheep urine-derived nitrous oxide emissions from a semi-improved upland soil. Five factors were tested at different levels: soil type (two types), soil percentage water-filled pore space (three levels), urine nitrogen concentration (four levels), urine volume (two levels) and temperature (two levels) in incubation experiments using the denitrification incubation system (DENIS), a flow-through soil core incubation system which allows automated measurement of carbon dioxide, nitrous oxide, nitric oxide and nitrogen gas emissions under an 80:20 helium:oxygen atmosphere.

The work represents a valuable contribution to the field of agricultural nitrous oxide research in the following ways: i) upland soils, which are important for UK sheep farming have been much less studied that lowland soils and may have quite different urine-derived nitrous oxide emission responses; ii) the design provides more information about the interactive effects of factors affecting sheep urine-derived nitrous oxide emissions than previous studies in the literature; and iii) use of the unique DENIS laboratory allows high resolution determination of urine-derived soil gas emissions and in particular, nitrogen gas production, which is otherwise very difficult to measure, this is also the first time that urine has been applied in the DENIS laboratory.

While cumulative sheep urine-derived nitrous oxide emissions from the upland soils investigated were low under many of the condition combinations tested, results indicate that:
1- emissions are not negligible under all conditions and large, localised and transient nitrous oxide emissions can result from some urination events.
2- Soil percentage water filled pore space had the largest effect on sheep urine-derived cumulative nitrous oxide emissions, with higher water levels giving higher cumulative nitrous oxide emissions.
3- Increasing urine nitrogen concentration had the second largest effect on increasing cumulative nitrous oxide emissions and there was a significant positive interaction between soil percentage water filled pore space and nitrogen concentration (when both were high, nitrous oxide emissions were even higher).
4- Finally, there was also a significant interaction between soil percentage water filled pore space and soil type indicating that higher water levels had a larger effect on nitrous oxide emissions for one of the soils.

The findings will be of use to others within the field of study and provide information that could impact national greenhouse gas budgets and upland sheep farming practices
Exploitation Route The results from this study will be used to modify current EFs used in the agricultural inventory to estimate emissions from grazed uplands. It will also provide knowledge on the controlling factors of emissions, information useful for models and for developing strategies for mitigating emissions. in addition, the knowledge of this factors will be used to provide recommendations for grazing management.
Sectors Agriculture, Food and Drink,Environment

 
Description Revision of emission factors for the greenhouse gas inventory in the UK
Geographic Reach Multiple continents/international 
Policy Influence Type Citation in other policy documents
Impact The UK is an Annex I country for the reporting of greenhouse gas emissions to the United Framework Convention for Climate change. As such, the UK is committed to reducing its emissions according to International Agreements (for ex. the Kyoto protocol). The development of new Emission Factors for agriculture has a impact not only on the accounting of national emissions, but also on the application of mitigation strategies from the understanding on where the emissions come from, also to show compliance with the international demands for reduction.
 
Description GCRF-IAA
Amount £10,000 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 02/2017 
End 02/2017
 
Description Lawes and Gilbert PhD Studentship-Patricia Grau
Amount £50,000 (GBP)
Organisation Rothamsted Research 
Sector Academic/University
Country United Kingdom
Start 10/2017 
End 09/2021
 
Description STARS Centre for Doctoral Training-Harry Barrat
Amount £50,000 (GBP)
Funding ID NE/M009106/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 09/2017 
End 03/2021
 
Description Soils to Nutrition, S2N as a Co-I
Amount £8,500,000 (GBP)
Funding ID S2N ISPG 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 04/2017 
End 03/2022
 
Title Database of nitrous oxide emissions from the application of livestock urine to soils in a lab incubation 
Description Several incubations were carried out where sheep urine was applied to soil under different conditions of temperature, soil moisture, N concentration and volume of urine, soil type. Data comprises Nitrous oxide, nitrogen gas, nitric oxide, carbon dioxide and methane emissions as well as soil N, C and microbiology 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact This data is been used to inform a model that will comprise different parameters from this project, including field emissions, vegetation, soil physical and chemical parameters. Also included is urine composition and potential relationship to pasture consumed by livestock. The data is also been used in statistical analysis including multivariate and Taguchi. 
 
Title New emission factors for nitrous oxide and methane emissions from agriculture in the UK 
Description From a large programme of research, we have developed new emission factors for nitrous oxide emissions from soils and manure; methane emissions from livestock and manures. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
Impact The data has been included in the inventory of greenhouse gases from the UK to estimate emissions 
URL http://www.environmentdata.org/archive/ghgno:676
 
Title Soil spatial survey from lowland sheep 2016 
Description Soils and greenhouse gas measurements in a sheep grazed field were carried out to match measurements on the uplands sheep in Wales 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? No  
Impact This data will be useful for making correlations between soil and gas measurements. This will provide knowledge on whether proxies can be used to estimate emissions from soils. 
 
Description Animal behaviour influence on N2O emissions 
Organisation University of Texas
Country United States 
Sector Academic/University 
PI Contribution The idea of relating emissions of nitrous oxide to animal behaviour, joining my expertise in atmospheric emissions with the behaviour knowledge of the colleague in Texas
Collaborator Contribution The understanding of animal behaviour
Impact Presentations in conferences as listed in the relevant section of this award
Start Year 2016
 
Description 3rd Conference of Greenhouse Gas Emissions in Animal Agriculture Production Systems of Latin America (GALA 2017) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This conference gathers researchers in Latin America working on greenhouse gases and agriculture. Laura Cardenas gave 2 presentations: 'N2O emissions pathways from soils under grazing'; 'What and How' during the conference that took place in October 4th to 6th, 2017 in Colonia, Uruguay
Year(s) Of Engagement Activity 2017
 
Description AAB Conference on Sustainable Intensification, Harpenden, 28-30 November 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Presentation of paper: Charteris, A., Loick, N., Marsden, K., Chadwick, D., Mead, A., Cardenas. L. (2017) Using factorial laboratory incubation experiments to develop simple indicators of greenhouse gas fluxe
Year(s) Of Engagement Activity 2017
 
Description Global Farm Platform conference, 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of paper: Cardenas et al., Grazing behaviour, urine composition and soil properties are key drivers of nitrous oxide emissions from livestock urine in the uplands (Uplands-N2O) at the GFP, Bristol, January 2016
Year(s) Of Engagement Activity 2016
 
Description Greenhouse Gas and Animal Agriculture conference 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of paper: D.R. Chadwick, L. M. Cardenas, N. Donovan, T. Misselbrook, J. Williams, R. Thorman, K. McGeough, C. Watson, M. Belle, S. Anthony, R.M. Rees. Nitrous oxide emissions from livestock urine and dung at the GGAA conference 14-18 Feb 2016, Melbourne.
Year(s) Of Engagement Activity 2016
 
Description Presentation at the 18th International Nitrogen Workshop 2016, Lisbon 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of paper: Rees, RM, Cloy JM, Bell M, Watson CJ, McGeough KL, Cardenas L, Williams J, Chadwick D. Nitrous oxide emissions from UK grasslands - measurements and mitigation at the 18th International Nitrogen Workshop 2014, Lisbon
Year(s) Of Engagement Activity 2014
 
Description Presentation at the 18th International Nitrogen Workshop 2016, Lisbon 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of paper: Cardenas L, Camp, V, Donovan, N, Hodgson, C, Misselbrook, T, McGeough, K, McNeill, G, Laughlin, R, Watson, C, Bell, M, Rees, B, Chadwick, D. IMPACT OF A NITRIFICATION INHIBITOR (DCD) ON N2O EMISSIONS FROM URINE APPLIED TO A UK GRASSLAND at the 18th International Nitrogen Workshop 2014, Lisbon
Year(s) Of Engagement Activity 2014
 
Description Presentation at the 19th International Nitrogen Workshop 2016, Sweden 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of paper: V. S. CIGANDA, M. LOPEZ, M. REPULLO, T. CLOUGH, L. CARDENAS, POTENTIAL INHIBITOR EFFECT OF HIPPURIC ACID ON NITROUS OXIDE EMISSIONS FROM GRASSLAND ON A HEAVY CLAY SOIL at the 19th International Nitrogen Workshop 2016, Sweden
Year(s) Of Engagement Activity 2016
 
Description Presentation at the 19th International Nitrogen workshop 2016, Sweden 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of paper: Cardenas, Balzter, Holmberg, Jones, King, Lush, Marsden, Perotto, Whellan, Wilson, Chadwick, GRAZING BEHAVIOUR, URINE COMPOSITION AND SOIL PROPERTIES ARE KEY DRIVERS OF NITROUS OXIDE EMISSIONSFROM LIVESTOCK URINE IN THE UPLANDS (UPLANDS-N2O) at the 19th International Nitrogen Workshop 2016, Sweden.
Year(s) Of Engagement Activity 2016
 
Description Presentation at the 20th International Nitrogen Workshop 2018, Rennes, France 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of the paper: Exploring the spatial variability of N2O emissions from a grazed upland and lowland site, by Charteris, Harris, Marsden, Harris, Guo, Beaumont, Taylor, Sanfratello, Jones, Whelan, Cardenas, Chadwick
Year(s) Of Engagement Activity 2018
 
Description Presentation at the 20th International Nitrogen Workshop 2018, Rennes, France 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of the paper: Interactive effects of the factors controlling urine-N2O emissions from an upland soil by: Charteris, Marsden, Castellano-Hinojosa, Loick, Chadwick, Ravella, Mead, Field, Whelan, Cardenas
Year(s) Of Engagement Activity 2018
 
Description Presentation at the EGU Vienna, May 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of paper: L. M. Cardenas, D.R . Chadwick, T. H. Misselbrook, N. Donovan, R. Dunn, B. Griffith, R.J. Orr, K. A. Smith, R. M. Rees , M. Bell, C. J. Watson , K. L. McGeough, G. McNeill, J.R. Williams, J. M. Cloy , R. E. Thorman, M. S. Dhanoa. Heterogeneity of gaseous emissions in soils-spatial vs temporal variability. POSTER PRESENTATION at EGU 2015.
Year(s) Of Engagement Activity 2015
 
Description Presentation at the EGU Vienna, May 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of paper: Rees, RM, Cloy JM, Bell MJ, Watson CJ, McGeough KL, Cardenas L, Williams JR, Chadwick DR. Nitrous oxide emissions from UK grasslands - measurements and mitigation. Crop-Livestock-Forest systems conference in Brazil. ORAL PRESENTATION by Bob Rees at EGU 2015.
Year(s) Of Engagement Activity 2015
 
Description Research Partnership Building Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Workshop held from 8th-10th Febraury 2017 at the ILRI (International Livestock Research Institute) Campus in Nairobi, Kenya (BecA [Biosciences eastern and central Africa] is also based on the campus and it is also referred to as the BecA-ILRI Hub)
There were attendees from:
- ILRI
- The Mazingira Centre
- CIAT
- CIMMYT
- IITA
- CTLHG
- The Roslin Institute
- University of Cambridge
- Kenyatta University
- Bahir Dar University
Year(s) Of Engagement Activity 2017
 
Description Teaching module in CIHEAM, Zaragoza, Spain, 14-16/3/2018 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Laura Cardenas taught a module in the course: 'Mitigation of greenhouse gas emissions in agriculture: concepts, methods and simulation tools'
Year(s) Of Engagement Activity 2017