
%0 Journal Article
%A Burkitt, L. L. 
%A Gourley, C. J. P. 
%A Sale, P. W. G. 
%T Phosphorus auditing cannot account for all of the phosphorus applied to different pasture soils
%J Soil Research
%D 2004/02/13
%V 42
%N 1
%P 89-98
%K budget, mass-balance, reapplication, nutrient loss, vertical movement, sorption, buffering, fertiliser.
%R https://doi.org/10.1071/SR03025
%U https://www.publish.csiro.au/paper/SR03025 
%X Five field sites established in the high rainfall zone of southern Victoria were used to examine the downwards vertical movement of phosphorus (P) fertiliser on soils which ranged in P sorption capacity. Fertiliser was applied either as a single application of 280 kg P/ha at the beginning of the experiment (April 1998), or as 35 kg P/ha reapplied every 6 months (totalling 210 kg P/ha by the end of the third year). Soil cores were sampled in June 2001 to a depth of 40 cm, and soil at depths of 0&#8211;5, 5&#8211;10, 10&#8211;20, 20&#8211;30, and 30&#8211;40 cm was analysed for a range of soil properties and total P concentration.Total P concentration changed very little down the profile, indicating that there was minimal vertical movement of P fertiliser below the 10 cm layer of 5 pasture soils following the single application of 280 kg P/ha or 35 kg P/ha reapplied every 6 months. Soils with low to moderate surface P sorption capacity showed a trend for higher total P concentrations at depth. However, quantitative relationships between vertical P movement and soil properties at depth were poor. A P audit resulted in variable recovery of the applied P (45&#8211;128%) in the surface 40 cm at each of the 5 sites. Consistently low P recoveries were achieved at one site, where the surface soil had a high P sorption capacity. Some applied P may have bypassed the high P sorbing surface layers at this site through macropore flow and moved beyond the 40 cm sampling zone, or have been lost to surface runoff. These results question the usefulness of P audit or mass-balance methods for accounting for P movement in a pasture-based system, as spatial heterogeneity of soil properties, both horizontally and vertically, was high in the current study. 
