Chemical speciation and fate of tripolyphosphate after application to a calcareous soil

Table 2 Bulk soil chemical analysis and XAS linear combination fitting results for the second application of TPP

Label	Depth (m)	Soil^a pH	Total Elemental Concentrations^b				Ca:Mg ratio	Labile^c extractable P (mg/kg soil)	LCF analysis results^d,e		Reduced chi²
Label	Depth (m)	Soil^a pH	Ca (mg/kg soil)	Mg (mg/kg soil)	P (mg/kg soil)	Fe (mg/kg soil)	Ca:Mg ratio	Labile^c extractable P (mg/kg soil)	Adsorbed P (%)	Ca-P species (%)^f	Reduced chi²
1b	1.82	7.8	22,800	15,200	820	24,700	1.5:1	74	10	96	0.00743
2b	3.66	7.8	29,900	17,300	870	27,300	1.7:1	79	24	76	0.00192
3b	1.82	7.8	24,800	14,100	790	25,000	1.8:1	71	18	81	0.00074
4b	3.66	7.4	23,900	15,900	880	29,600	1.5:1	60	41	61	0.00104
5b	1.82	7.9	22,200	13,800	750	25,200	1.6:1	85	43	57	0.00117
6b	3.04	7.9	1340	3140	3230	16,700	0.4:1	85	63	40	0.00139
7b	3.66	7.6	49,700	29,400	780	29,400	3.2:1	82	32	70	0.00140
8b	1.82	7.8	25,300	15,300	880	26,700	1.7:1	19	31	71	0.00130
9b	3.66	7.8	26,300	17,000	920	28,100	1.5:1	27	36	63	0.00155
10b	1.82	7.8	33,000	15,100	960	26,900	2.2:1	24	42	61	0.00059
11b	3.66	7.5	18,100	14,400	1000	39,200	1.2:1	62	31	70	0.00100

^aSoil pH accurate to ± 0.1
^bVia total XRF elemental analysis, concentrations are accurate to ± 10%
^cCombination of H₂O and NaHCO₃ extractable P
^dEo Shift constrained to zero
^e% Relative contribution to XAS signal; models are unconstrained and not equal to 100%
^fRelative sum of the contribution from calcium phosphate mineral species

ISSN: 1467-4866