# Phosphorus Distribution in Soils from Australian Dairy and Beef Rearing Pastoral Systems
## 5 Conclusions  
The results obtained in this study indicate that soil type, fertiliser P application rate and timing, and moisture variations had significant influence on soil P measurements and P speciation by NMR analysis. The lowest soil P concentrations were found in soil samples from sites with no recent inorganic fertiliser P inputs and this correlated well with the observed signal intensities of the NMR spectra. Soils from Maffra area which received moisture from both rainfall and boarder-check (flood) irrigation had much higher organic P (combined monoester P and diester P) than those from the Warragul area. Whether this highlights the difference moisture may play in the formation of higher organic P component in soil is unclear and requires further detailed investigation. On the other hand, the soils from the Warragul area which received higher fertiliser P addition had much higher orthophosphate proportion (67.0% on average) and total P (2059 mg P kg\({}^{-1}\) on average) than soils in the Maffra area (57.6% and 1822 mg P kg\({}^{-1}\), respectively, on average) which received much less fertiliser P addition. Thus, highlighting the importance of application rate of fertiliser P in management practices applied to ensure optimum plant available P.  
The soil type also had a major influence on soil P concentrations and speciation. On average, orthophosphate contributions were 5.5% lower in Dermosols compared to those of Ferrosols, and even lower (9.2%) when identical fertiliser P inputs and management strategies were employed. Even Sodosols were on average 14.7% lower in orthophosphate than Ferrosols. In contrast, the organic P (combined monoester P and diester P) proportion in Sodosols was on average 5.8% and 11.7% higher than those of Dermosols and Ferrosols, respectively. The pyrophosphate proportions were also generally higher in Sodosols than in Dermosols and Ferrosols. It is therefore recommended that more careful consideration must be given to soil type when undertaken or investigating management practices that are designed to assess and ensure optimum plant available P.  
As only fourteen sampling sites were considered, the results reported in this study only provide a snapshot of a particular moment in time. Further sampling, in-depth monitoring and characterisation of different soils are necessary to enable more definitive links to be made between soil properties and site management variables.  
The authors would like to acknowledge Monash University and Dairy Australia for providing funding for this project. The authors also wish to thank the University of Adelaide, Department of Soil and Land Systems, in particular Ms [PERSON], for providing access and expertise to \({}^{31}\)P NMR spectrometer.  
[PERSON] contributed to initiation, experimental design, data interpretation, reviewing, revisions and write ups. [PERSON] contributed to experimental design, experimental work, data interpretation and associated write up. [PERSON] contributed to specialised experimental work, reviewing and interpretation.  
The authors declare no conflict of interest.