
%0 Journal Article
%A Smettem, K. R. J. 
%A Bristow, K. L. 
%A Heng, L. K. 
%A Oliver, Y. M. 
%A Ford, E. J. 
%T Obtaining soil hydraulic properties for water balance and leaching models from survey data. 1. Water retention
%J Australian Journal of Agricultural Research
%D 1999/02/12
%V 50
%N 2
%P 283-289
%K 
%R https://doi.org/10.1071/A97074
%U https://www.publish.csiro.au/paper/A97074 
%X A physico-empirical 2-parameter power law model of the draining water retention curve (WRC) based solely on clay content is described and further developed using 6 datasets obtained from Australian and New Zealand soils. The slope of the WRC, or pore-size distribution index, is well described by the model but the bubbling pressure, or inflection point is poorly described. Without a good estimation of the bubbling pressure it is not possible to scale the physico-empirical model to the WRC. To achieve the scaling, a single measured point on the WRC in the unsaturated range is required. The resulting estimated water contents may be satisfactory for application within broad-scale leaching risk models and for generalised extrapolation of results from detailed experimental sites but caution is still required for quantitative applications of nitrate leaching models at a particular site. It is concluded that soil surveys could usefully include a single WRC measurement in the field at each sampling location to improve their utility for water and chemical transport modelling. 
