Abstract
Environmental Life Cycle Assessment (LCA) is an approach for assessing the comprehensive environmental impacts of human activities; effects are quantified along the life cycle from extraction of raw materials, through processing, manufacturing, transportation, use and on to final disposal. LCA was developed for assessing industrial systems, and agricultural systems are sufficiently different that this area of application introduces new methodological issues for all phases of LCA. These issues are addressed in the thesis; additionally, it explores issues related to the wider use of LCA in decision-making. New methods are presented for assessing use of solar energy and water, soil quantity and quality, and biodiversity. Use of solar energy is assessed in relation to total incident radiation, and use of water in relation to average annual rainfall reaching land in a system under analysis. Soil quantity and quality are assessed assuming that soil is an ancillary item in LCA; this requires careful modelling, use of Organic Matter and Soil Compaction Indicators, and inclusion of eroded soil in assessing abiotic resource depletion. A method for assessing physical habitat maintenance and change is presented which highlights some generic features of LCA mitigating against its acceptance among some stakeholders. A case study of breadmaking wheat production demonstrates practical application of the methods. This suggests it may be equally, or even more, relevant to determine preferred locations of production rather than preferred farming practices in seeking to maximise the environmental performance of agricultural systems. More attention is needed to ensuring the usefulness of LCA results. They should be accurate, relevant, understandable and meaningful to stakeholders, and the LCA approach must be accepted as a legitimate form of analysis. This requires more flexibility in LCA methodology to adapt it to different decision-making contexts, balanced by a greater focus on the process of undertaking LCA.