Purpose -To identify and analyse the beliefs of value-chain intermediaries regarding the production and marketing of food products conforming to environmentally sustainable standards.Design/methodology/approach -The methodology was in-depth, semi-structured, face-toface interviews with senior managers of food companies across the value chain.

Attempts to reduce land degradation by influencing the management behaviour of farmers will be better informed when the relative importance of factors influencing the use of %onservation practices aimed at enhancing longer-term land productivity can be quantijed. Land managers' perceptions of the technical feasibility and profitability of such practices will play an important role in the decisions about their use. Of particular interest is the relative importance of an individualS perceptions of the profitability of conservation behaviours and the individual's conservation orientation. In a pretest-post test study the influence of prior perceptions about two 'conservation' practices, and of environmental orientation, on the subsequent behaviour of farmers is investigated. A logistic regression model is developed to show the relative influence of perceptions of profitability and technical feasibility and of personal environmental concern on the choice of conservation practices. Perceived Profitability was the most important factor influencing the use of conservation practices.The economic costs to a landholder of many conservation practices may exceed the on-farm benefits on a short-term and possibly long-term basis. The lack of immediate financial incentive in a dynamic farm economy may result in many land-* John Cay is an Associate Professor and Head,

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The loss of biological diversity is a major environmental problem occurring on a global scale. Human-environment researchers have an important role in shaping policy and programs at a local, national and international level. This paper explores human preference for landscapes relative to ecological quality and assesses the relationship between these preferences and land management behavior. A survey of more than 1000 urban and rural residents of southeastern Australia examined preferences for 36 black and white photographs of native vegetation. There was more commonality than difference between urban and rural preference for different arrays of native vegetation. Preference for Eucalyptus species was higher than preference for non-Eucalyptus species. Preference ratings indicate minimal differences across landscapes with distinct variation in ecological quality. The study suggests that preference for landscapes of relatively high ecological quality is associated with behavior that is protective of this resource.AUTHORS' NOTE: The research reported in this paper was funded by the Land and Water Resources Research and Development Corporation and Environment Australia. We are grateful to Robert Edgar for assistance with this project.3 The earth's rich variety of life forms -plants, animals and microorganisms as well as the genes they contain and the ecosystems they form -are a global asset of immeasurable value.Despite this, human activity continues to result in the extinction of species world-wide; the biological diversity on which we depend is severely threatened.At a global level, concern for biodiversity loss is expressed in the international Convention on Biological Diversity sponsored by the United Nations Environment Program (UNEP); Australia became a signatory to the Convention on World Environment Day, 1992 (Commonwealth of Australia, 1996a). At a community level, however, there is relatively little concern for loss of species and ecosystems. In 1998, 22% of Australians surveyed considered loss of trees and ecosystems to be an important environmental issue and less than 10% were concerned about loss of animals and wildlife (Australian Bureau of Statistics, 1998). Australians were more likely to be concerned about pollution of air and waterways; similar priorities have been noted in the United States of America (Bidwell & Barro, 1996).Lack of public concern is an important consideration since preventing further loss of biological diversity depends on cooperation of government, industry and the broader community. In Australia, the largely urban community has a particularly important role, sustaining political will and the financial base from which to implement the National Biodiversity Strategy (Commonwealth of Australia, 1993). While the rural population is much smaller, its contribution is equally important, managing the declining amount of fragile remnant native vegetation that is found on private land (Commonwealth of Australia, 1996b).There is clearly an urgent need to find more effective me...

Salt and water movement was measured in unsaturated frozen soil columns incubated under a thermal gradient for 3, 6, or 9 weeks. Both water and salt moved from the warmer to cooler areas in the soil, creating a twofold concentration difference over a 24-cm distance. Movement of CaC12, LiI, and K2SO4 was studied in detail Cation exchange reactions and salt solubilities at high concentrations affected the movement. Although the results suggested that mass flow of dissolved salts in a liquid film of water was the principal transfer mechanism, both vapor and salt diffusion were sometimes significant. Thermal diffusion and salt sieving did not appear to be important.Since the vapor pressure of ice controls the water potential in frozen soil, the amount of unfrozen water and matric suction could be calculated from a water release curve and data from ice suspensions in salt solutions. These results led to the conclusion that mass flow in the liquid phase is described by Darcy's law. Thus, salt flow as well as net water transfer can probably be predicted in unsaturated frozen soil using information available from unfrozen systems.Additional Index Words: salinity, salt diffusion, thermal diffusion, salt separation, frost heaving. M OIST UNSATURATED SOIL freezes downward from the surface in the fall and is subject to varied thermal gradients throughout the winter (Benz et al., 1968). As the soil water freezes, small ice crystals form in the pore spaces. Not all of the water freezes under temperatures commonly experienced in the field. A liquid-like film 10 to 40A thick remains at the ice-air interface. Liquid films of varying thicknesses also remain in the soil particleice interfaces and in the soil particle-air interfaces (Anderson, 1970).Since ice crystals freeze out of a solution in a pure state, all soluble salts are forced into the unfrozen water films and may form relatively concentrated brines. The vapor pressure of ice is less than that of pure liquid water. Consequently, water will continue to crystallize from the soil solution until the combined osmotic and matric forces reduce the solution's vapor pressure to that of the ice (Hoeckstra, 1966;Low et al., 1968). Under natural conditions in the field, temperature gradients always exist, and liquid water tends to move from warmer to cooler areas (Fergusen et al., 1964). A spontaneous vapor pressure gradient in this same direction is fixed by the temperature of the ice phase. While some movement is in the vapor phase, most of the flow is in the unfrozen liquid films (Hoeckstra, 1966;Benz et al., 1968 apparent that salt will also move from warmer to cooler areas in the unsaturated frozen soil.Most of the liquid phase movement occurs along the water films adsorbed to the soil particles. While there are liquid films in the ice crystal air interfaces, they comprise a small fraction of the total unfrozen water in unsaturated soil because of the relatively small surface area of the ice crystals compared to that of the soil particles (Anderson, 1970). As the water ...

The present status of knowledge concerning thermally induced transport of moisture in soil is reviewed. This includes the various theories on mechanisms of transport and experimental data showing the magnitude of moisture flow in various porous materials. Wherever possible these data were chosen to show the relative importance of thermal versus head‐type flow and some general trends are noted. Simple equations are developed to describe the thermally induced moisture flow near the soil surface which arises from transient thermal gradients produced by the diurnal temperature cycle. Calculations of the moisture flux over 2 ten‐hour time intervals for a typical field situation indicate that thermal water transport should be considered whenever moisture, salt, or heat fluxes are being studied in the soil's surface layers. The upward flow of soil water against a moisture content gradient in the winter is also considered. A sample calculation of the amount of thermally driven moisture was made using data available in the literature. The result suggested that the thermal moisture flow was too small to account for the net movement of soil moisture into the frost zone.

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