A measure of soil P status in agricultural soils is generally required for assisting with prediction of potential P loss from agricultural catchments and assessing risk for water quality. The objectives of this paper are twofold: (i) investigating the soil P status, distribution, and variability, both spatially and with soil depth, of two different first-order catchments; and (ii) determining variation in soil P concentration in relation to catchment topography (quantified as the "topographic index") and critical source areas (CSAs). The soil P measurements showed large spatial variability, not only between fields and land uses, but also within individual fields and in part was thought to be strongly influenced by areas where cattle tended to congregate and areas where manure was most commonly spread. Topographic index alone was not related to the distribution of soil P, and does not seem to provide an adequate indicator for CSAs in the study catchments. However, CSAs may be used in conjunction with soil P data for help in determining a more "effective" catchment soil P status. The difficulties in defining CSAs a priori, particularly for modeling and prediction purposes, however, suggest that other more "integrated" measures of catchment soil P status, such as baseflow P concentrations or streambed sediment P concentrations, might be more useful. Since observed soil P distribution is variable and is also difficult to relate to nationally available soil P data, any assessment of soil P status for determining risk of P loss is uncertain and problematic, given other catchment physicochemical characteristics and the sampling strategy employed.

Crop rotations are allocations by growers of crop types to specific fields through time. This paper aims at presenting i) a systematic and rigorous mathematical representation of crops rotations; and ii) a concise mathematical framework to model crop rotations, which is useable on landscape scale modelling of agronomical practices. Rotations can be defined as temporal arrangements of crops and can be classified systematically according to their internal variability and cyclical pattern. Crop sequences in a rotation can be quantified as a transition matrix, with the Markovian property that the allocation in a given year depends on the crop allocated in the previous year. Such transition matrices can represent stochastic processes and thus facilitate modelling uncertainty in rotations, and forecasting of the long-term proportions of each crop in a rotation, such as changes in climate or economics. The matrices also permit modelling transitions between rotations due to external variables. Computer software was developed that incorporates these techniques and was used to simulate landscapescale agronomic processes over decadal periods.

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Following an outline of the different types of agglomeration economy, consideration is given to transaction costs. Transaction costs may have a definite spatial dimension because institutional, commercial, cultural, and language characteristics are differentiated across the geographic space separating market agents. The concept of transaction space is introduced to represent the spatial differentiation of these characteristics, and this concept is used to cast light on how space can contribute to coordination and agency problems that raise transaction costs. Contractual agreements that are rearranged, so as to span a less heterogeneous transaction space, permit the reduction of transaction costs. Agglomeration can then be interpreted as an alternative to hierarchical structures within firms in economizing on transaction costs. The paper concludes with illustrations of how this framework may help to understand the spatial implications of corporate restructuring and new information technologies. Copyright 2005 Blackwell Publishing Ltd..

Across the decade to 2007, a combination of house price appreciation and relaxed credit constraints gave a boost to consumption through the mechanism of mortgage equity withdrawal (MEW). Arguably, this kept developed economies buoyant, even through periods of recession. This paper uses panel data on British and Australian homeowners to show that, notwithstanding its macro-economic effects, such borrowing has far-reaching implications for the micro-economy of households. The data indicate that, for the period 2001-2005, equity borrowing was a common tactic. The sums involved were not trivial, were not limited to older cohorts, or the province simply of the rich. In fact, the events and circumstances associated with equity borrowing at the zenith of the last housing cycle were consistent with an insurance, as well as a general consumption, role for MEW. As house prices fall and credit constraints are re-introduced, the options for such borrowing will shrink. Recent financial shocks may, by reducing the availability of a key channel from housing wealth into consumption, prompt a crisis of welfare. They pose challenges for housing and social policy as well as for economic management.Mortgage equity withdrawal, mortgage debt, equity borrowing, housing equity, precautionary savings, panel data,

In Australia and other ‘homeownership societies’ it has been conventional to think of housing pathways in terms of a smooth linear progression, leading to outright ownership in middle age and a retirement buffered by low housing costs. This vision of the welfare role of homeownership is an important buttress of Australian retirement incomes policy. However, this vision has been challenged in recent years as growing numbers of older Australians lose home ownership and consequently transition onto housing assistance programmes. Using Household, Income and Labour Dynamics in Australia (HILDA) survey data we analyse pathways into housing assistance. A transition model is estimated that specifies older Australians’ pathway to housing assistance status as a function of key socioeconomic and demographic determinants such as wealth and debt, health, marital status, tenure and employment history programmes. We find that those losing home ownership have a higher chance of becoming users of housing assistance programmes than similarly positioned longer-term renters, a result that is particularly evident among ex-owners that are exposed to adverse biographical events. The theoretical implications of our findings for the scholarship on housing pathways are discussed.

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