Katharina Plassmann

Carbon footprinting of lamb and beef production systems: insights from an empirical analysis of farms in Wales, UK

Carbon footprinting is an increasingly important method of communicating the climate change impacts of food production to stakeholders. Few studies utilize empirical data collected from farms to calculate the carbon footprints of lamb and beef. Data from two farms in Wales, UK, were employed to undertake such an analysis for two system boundaries. Within a system boundary that considers the embodied greenhouse gases (GHGs) in inputs and on-farm emissions, producing 1 kg of lamb releases 1·3–4·4 kg CO 2 eq/kg live weight (case study farm 1) and 1·5–4·7 kg CO 2 eq/kg live weight (case study farm 2). The production of beef releases 1·5–5·3 and 1·4–4·4 kg CO 2 eq/kg live weight. Within a wider system boundary that also includes GHG emissions from animals and farm soils, lamb released 8·1–31·7 and 20·3–143·5 kg CO 2 eq/kg live weight on the two case study farms, and beef released 9·7–38·1 and 18·8–132·6 kg CO 2 eq/kg live weight. The difference in emissions for this system boundary relates to nitrous oxides emitted from the organic soils on case study farm 2. These values overlap with nearly all other studies of GHG emissions from lamb and beef production. No direct comparisons between studies are possible due to substantial differences in the methodological approaches adopted.

The effects of low levels of nitrogen deposition and grazing on dune grassland

Coastal sand dunes are considered to be threatened by the atmospheric deposition of nitrogen (N); however, experimental investigations of the effects of N deposition on dune vegetation and soil using realistic N loads and sites with low background deposition are scarce. This study reports the effects of low levels of fertilisation with N and phosphorus (P) on the vegetation, above-ground biomass, plant tissue chemistry and soil chemistry of fixed dune grasslands. In addition, the impacts of grazing management and its potential to mitigate adverse effects of N fertilisation were examined. Four N treatments (unwatered control, watered control, +7.5 kg ha(-1) year(-1), +15 kg ha(-1) year(-1)) were combined with three grazing treatments (ungrazed, rabbit grazed, rabbit and pony grazed). In a separate experiment, effects of fertilisation with both N (15 kg ha(-1) year(-1)) and P (20 kg ha(-1) year(-1)) were investigated. Vegetation composition was assessed using the point quadrat method. Above-ground biomass, sward heights, tissue N and P concentrations and soil chemical parameters were also measured. After two years, N addition resulted in greater amounts of total above-ground biomass, bryophyte biomass and changes in bryophyte tissue chemistry. No effects on vegetation composition, sward height or soil parameters occurred. Fertilisation with both nutrients had a greater impact on above-ground biomass, sward heights and sward structure than N addition alone. The grazing treatments differed in their species composition. The changes observed after only two years of fertilisation may lead to community changes over longer time scales. Effects were observed even under heavy grazing with phosphorus limitation. Therefore, the upper critical load for N for dune grasslands may be below the previously proposed 20 kg ha(-1) year(-1) and grazing may not mitigate all negative effects of N deposition.

Can atmospheric input of nitrogen affect seed bank dynamics in habitats of conservation interest? The case of dune slacks

ABSTRACT Questions: Does the increased atmospheric deposition of nitrogen, which can have major effects on the established vegetation of nutrient-poor habitats, also impact germination from the soil seed bank? Location: Coastal dune slacks at Newborough Warren, Wales, UK. Methods: The effects of nitrogen addition (15 kg.ha−1.a−1) on seed germination from the soil seed bank were investigated using the seedling emergence method between September 2004 and February 2005. Results: More seedlings emerged from fertilised samples than unfertilised controls. Most species showed enhanced germination after fertilisation with nitrogen, with seedling numbers statistically significantly greater in nitrogen addition samples in a quarter of species abundant enough for analysis. Species that responded positively to fertilisation were species with low Ellenberg indicator values indicative of infertile sites. Conclusions: Most species showed increased germination after fertilisation with nitrogen, including early successional species normally growing in nutrient-poor conditions. This suggests that the increased atmospheric deposition of nitrogen probably not only impacts on established vegetation, but also has the potential to alter seed bank dynamics. Nomenclature: Stace (1997).

Modular Extrapolation Approach for Crop LCA MEXALCA: Global Warming Potential of Different Crops and its Relationship to the Yield

MEXALCA (Modular EXtrapolation of Agricultural LCA) extrapolates crop inventory data and impacts from an original country inventory to all producing countries worldwide. This allows estimates of worldwide means weighted by production volumes and of the environmental impact distribution. In this paper, the relationship between the yield and the environmental impacts is analysed in order to test whether the yield alone can be used as an extrapolation criterion. The results show that the global warming potential (GWP) per kg decreases with increasing yields for the means of the 27 studied crops. When comparing the production of a crop in different countries, the relationship between GWP per kg and yield exists only for those crops where the contribution from basic cropping operations and tillage to the GWP is significant. Considering the yield alone therefore generally allows only a poor approximation of the GWP.