Summary Climate change associated with greenhouse gas (GHG) emissions may have important implications for Europe's grasslands. Projected scenarios indicate that increased temperatures and CO2 concentrations have the potential to increase herbage growth and to favour legumes more than grasses, but changes in seasonal precipitation would reduce these benefits particularly in areas with low summer rainfall. Further implications for grasslands may arise from increased frequency of droughts, storms and other extreme events. Potential farm‐scale adaptive responses to climate change are identified. Grassland agriculture also contributes to GHG emissions, particularly methane and nitrous oxide, and management of grassland affects net carbon balances and carbon sequestration. Management options are identified for mitigating grassland's contribution to GHG emissions which need to be developed in a holistic way that also considers other pressures.

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A B S T R A C TMathematical models, such as the DNDC (DeNitrification DeComposition) model, are powerful tools that are increasingly being used to examine the potential impacts of management and climate change in agriculture. DNDC can simulate the processes responsible for production, consumption and transport of nitrous oxide (N 2 O). During the last 20 years DNDC has been modified and adapted by various research groups around the world to suit specific purposes and circumstances. In this paper we review the different versions of the DNDC model including models developed for different ecosystems, e.g. Forest-DNDC, Forest-DNDC-Tropica, regionalised for different areas of the world, e.g. NZ-DNDC, UK-DNDC, modified to suit specific crops, e.g. DNDC-Rice, DNDC-CSW or modularised e.g. Mobile-DNDC, Landscape-DNDC. A 'family tree' and chronological history of the DNDC model is presented, outlining the main features of each version. A literature search was conducted and a survey sent out to c. 1500 model users worldwide to obtain information on the use and development of DNDC. Survey results highlight the many strengths of DNDC including the comparative ease with which the DNDC model can be used and the attractiveness of the graphical user interface. Identified weaknesses could be rectified by providing a more comprehensive user manual, version control and increasing model transparency in collaboration with the Global Research Alliance Modelling Platform (GRAMP), which has much to offer the DNDC user community in terms of promoting the use of DNDC and addressing the deficiencies in the present arrangements for the models' stewardship.

The establishment of sustainable soil waste management practices implies minimizing their environmental losses associated with climate change (greenhouse gases: GHGs) and ecosystems acidification (ammonia: NH3). Although a number of management strategies for solid waste management have been investigated to quantify nitrogen (N) and carbon (C) losses in relation to varied environmental and operational conditions, their overall effect is still uncertain. In this context, we have analyzed the current scientific information through a systematic review. We quantified the response of GHG emissions, NH3 emissions, and total N losses to different solid waste management strategies (conventional solid storage, turned composting, forced aerated composting, covering, compaction, addition/substitution of bulking agents and the use of additives). Our study is based on a meta-analysis of 50 research articles involving 304 observations. Our results indicated that improving the structure of the pile (waste or manure heap) via addition or substitution of certain bulking agents significantly reduced nitrous oxide (N2O) and methane (CH4) emissions by 53% and 71%, respectively. Turned composting systems, unlike forced aerated composted systems, showed potential for reducing GHGs (N2O: 50% and CH4: 71%). Bulking agents and both composting systems involved a certain degree of pollution swapping as they significantly promoted NH3 emissions by 35%, 54%, and 121% for bulking agents, turned and forced aerated composting, respectively. Strategies based on the restriction of O2 supply, such as covering or compaction, did not show significant effects on reducing GHGs but substantially decreased NH3 emissions by 61% and 54% for covering and compaction, respectively. The use of specific additives significantly reduced NH3 losses by 69%. Our meta-analysis suggested that there is enough evidence to refine future Intergovernmental Panel on Climate Change (IPCC) methodologies from solid waste, especially for solid waste composting practices. More holistic and integrated approaches are therefore required to develop more sustainable solid waste management systems.