# Phosphorus Distribution in Soils from Australian Dairy and Beef Rearing Pastoral Systems
## 3 Results
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sampling** & \multirow{2}{*}{**Site**} & **7 to 5.3 ppm** & **5.3 to 2 ppm Monoester** & **0.5 to \(-\)1 ppm Diseter** & \(-\)4.5 to \(-\)5.5 ppm** \\
**Sites** & & **Orthophosphate (\%)** & **Phosphgate (\%)** & **Phosphgate (\%)** & **Pyrophosphate (\%)** \\ \hline  & W1 & 65.3 (0.6) & 31.0 (0.1) & 1.9 (0.1) & 1.8 (0.4) \\  & W2 & 67.3 (0.1) & 30.1 (0.5) & 1.5 (0.2) & 1.1 (0.4) \\ Warragul & W3 & 77.3 (1.6) & 19.8 (1.5) & 1.5 (0.3) & 1.4 (0.2) \\ Area & W4 & 73.6 (0.0) & 23.4 (0.1) & 1.5 (0.1) & 1.6 (0.0) \\  & W5 & 65.7 (1.2) & 28.6 (0.8) & 2.5 (0.2) & 3.1 (0.2) \\  & W6 & 67.7 (0.1) & 28.9 (0.4) & 1.8 (0.1) & 1.6 (0.4) \\  & W7 & 52.2 (2.2) & 39.6 (0.4) & 5.7 (0.9) & 2.6 (0.9) \\ \hline  & M1 & 66.4 (1.4) & 28.2 (0.6) & 2.0 (0.6) & 3.3 (0.2) \\  & M2 & 64.3 (0.3) & 29.1 (0.1) & 2.5 (0.0) & 4.1 (0.2) \\ Mafra & M3 & 46.5 (1.0) & 44.6 (0.3) & 3.8 (1.1) & 5.0 (0.2) \\ Area & M4 & 43.9 (2.1) & 46.4 (0.6) & 3.8 (1.7) & 5.9 (1.0) \\  & M5 & 49.8 (0.3) & 37.9 (0.0) & 3.8 (0.2) & 8.5 (0.1) \\  & M6 & 57.8 (3.7) & 33.0 (1.9) & 3.9 (1.3) & 5.2 (0.5) \\  & M7 & 74.3 (2.1) & 22.2 (2.1) & 1.3 (0.8) & 2.2 (0.8) \\ \hline Average & & 62.3 & 31.6 & 2.7 & 3.4 \\ \hline \hline \end{tabular} Standard deviations for duplicate NMR analysis shown in brackets.  
\end{table} 
Table 4: The percentage distribution of the total \({}^{31}\)P NMR signal across four diagnostic chemical regions. Figure 2: Solution \({}^{31}\)P NMR spectra of NaOH-EDTA soil extracts. As in previous studies, the most abundant P species in most of the soils was orthophosphate [18]. With a chemical shift from 7.0 to 5.3 ppm in the NMR spectra, orthophosphate accounts for between 43.9% and 77.3% of the total signal intensity in these soils. An exception was site M4, which contained marginally more (46.4%) monoester P than orthophosphate P (43.9%). Across all soils, monoester phosphate (between 5.3 and 2.0 ppm) represented 19.8% to 46.4% of the total P (average 31.6%). Diester phosphate (between 0.5 and \(-\)1.0 ppm) on average contributed 2.7% of signal intensity, whereas pyrophosphate (between \(-\)4.5 and \(-\)5.5 ppm) averaged 3.4%. Diester phosphate appeared to account for a lower proportion of the signal intensity for the Warragul samples (averaging 2.3%) than those from the Maffra area (3.0%). This difference becomes more apparent when the contribution of W7 is removed from these calculations, lowering the average diester phosphate contribution for the Warragul area to 1.8%. Site W7 contained the most diester phosphate (5.7%) of all the soils tested. This site was different to others due to its unique soil type, a grey sandy loam. Based on other soils surrounding its location, soil from site W7 featured Dermosol characteristics. Figure 3 shows the scatter plots obtained between the concentrations of the various inorganic and organic phosphates found in all soil samples. It is obvious that, given the limited number of sampling sites considered in this initial study, it is difficult to identify clear correlation between many of these P species. Notwithstanding this limitation, correlation between the concentrations of some of these species is still clearly evident and these will be highlighted later in the discussion section. Figure 3: Scatter plots of the trend between some of the inorganic and organic P levels in the soil samples. (**a**) Colwell P, Olsen P, water extractable P (WEP), calcium chloride extractable P (CCEP) and Total P as mg/kg; (**b**) Extractable total P, orthophosphate, monoester P, diester P and pyrophosphate as percentage (%).