The thesis is divided into two sections. Part I, a literature review, covers the methods available for the measurement of biological nitrogen fixation by legumes, but concentrates on the advantages and disadvantages of the acetylene reduction method, and also the factors which limit nitrogen fixation by legumes. Part II covers the experimental work, the results and conclusions. Acetylene reduction methods of measuring nitrogen fixation by white clover in pots and field cores of red and white clover were tested and a suitable method for regular routine assays was developed. The results from this work stressed the importance of establishing optimum procedures prior to routine sampling and to standardize sampling end incubation procedures to allow for comparative work between sites and treatments. A series of pot experiments were set up to investigate the effects of Mo, Co and Cu treatment on white clover grown in soil deficient in these elements. Little treatment response in terms of nitrogen fixation, dry matter yields or plant-N content was found. The results of field work during 1976 and 1977 showed the marked difference in magnitude end patterns of acetylene reduction activity of both red and white clover grown on upland and lowland sites, the effects of different varieties of white clover, the effects of fertilizer treatment and periodic defoliation. Estimates of total nitrogen fixed from the white clover sites were made but the difficulties in using acetylene reduction results for such estimates are stressed. The implications of the field results in the use of pasture legumes is discussed in the final conclusions.

There has been limited focus on the potential of 'agritourism' in Scotland, in terms of research and policy. In order to improve understanding of agritourism in practice, it is important to ensure that a link is made to theory. However, the agritourism literature revealed a lack of consistency and shared understanding in terms of what defines agritourism. To the agritourism literature this thesis contributes a novel agritourism framework based on three key characteristics. These three characteristics relate to: the nature of visitor interaction with agriculture; whether or not the product is based on a working farm; and whether or not the visitor experiences authentic working agriculture. The framework for agritourism is a flexible conceptual frame of reference, and can also be used as a research tool (the 'typology-based approach') to inform and facilitate agritourism research. In the context of the typology-based approach, interpretations of agritourism identified from the literature were consolidated with providers' and visitors' understanding of the concept in an empirically-based agritourism typology. Subsequently, the empirically-based typology was used to facilitate an investigation of supply and demand-side drivers of agritourism in Scotland. As a result, it has been possible to identify key relationships between supply and demand, and policy-relevant implications for agritourism in Scotland. Simultaneous analysis of agritourism supply and demand represents a novel approach in the context of the agritourism literature. In its predominant form, agritourism has been shown to generate a range of private benefits for agritourism providers and visitors in Scotland. However the potential of agritourism in niche forms extends even further, in terms of its potential to simultaneously generate private and public benefits, including increased public awareness of food and farming, sales of farm (and local) produce, and implementation of agri-environmental measures by the tourism market.

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