Skip to main content

Table 6 Concentrations and percentages of organic P compounds in extracts of whole soil or residues, determined by solution P-NMR spectroscopy

From: Characterizing the phosphorus forms extracted from soil by the Mehlich III soil test

  Extractant   AR-control AR-N AR-PL AR-PL-alum SK PEI Till Ref
Phosphonates Mehlich III Soil 1 (2) 2 (2) 5 (1) 5 (1) 1 (1) 2 (1) 0 (1)
  NaOH-EDTA Residue 2 (2) 2 (1) 4 (1) 8 (1) 3 (2) 3 (1) 2 (1)
  NaOH-EDTA Soil 2 (1) 5 (1) 5 (1) 8 (1) 5 (1) 5 (1) 3 (1)
Glucose 6-phosphate Mehlich III Soil 1 (1) 1 (1) 0 (0) 5 (1) 1 (1) 2 (1) 0 (1)
  NaOH-EDTA Residue 2 (1) 2 (1) 4 (1) 8 (1) 1 (1) 3 (1) 2 (1)
  NaOH-EDTA Soil 2 (1) 2 (1) 5 (1) 8 (1) 5 (1) 5 (1) 3 (1)
Choline phosphate Mehlich III Soil 1 (1) 1 (1) 0 (0) 5 (1) 1 (1) 0 (0) 0 (1)
  NaOH-EDTA Residue 4 (1) 5 (2) 4 (1) 8 (1) 3 (1) 3 (1) 4 (1)
  NaOH-EDTA Soil 5 (1) 4 (1) 5 (1) 8 (1) 2 (1) 5 (1) 3 (1)
Unknown 5.1 ppm Mehlich III Soil 1 (1) 1 (1) 3 (1) 5 (1) 2 (2) 0 (0) 0 (1)
  NaOH-EDTA Residue 4 (1) 5 (2) 8 (1) 8 (1) 8 (4) 6 (1) 28 (9)
  NaOH-EDTA Soil 11 (4) 9 (3) 10 (1) 25 (2) 15 (4) 11 (1) 10 (3)
Monoester 1 Mehlich III Soil 1 (1) 1 (1) 3 (1) 5 (1) 1 (1) 2 (1) 0 (1)
  NaOH-EDTA Residue 2 (1) 2 (1) 4 (1) 8 (1) 1 (1) 3 (1) 2 (1)
  NaOH-EDTA Soil 2 (1) 4 (1) 5 (1) 8 (1) 5 (1) 5 (1) 3 (1)
Monoester 2 Mehlich III Soil 2 (4) 3 (4) 8 (2) 30 (4) 6 (6) 3 (1) 2 (5)
  NaOH-EDTA Residue 9 (4) 18 (6) 12 (2) 91 (8) 11 (5) 6 (1) 32 (10)
  NaOH-EDTA Soil 21 (8) 18 (5) 14 (1) 41 (4) 25 (7) 16 (2) 25 (7)
Monoester 3 Mehlich III Soil 2 (3) 2 (2) 3 (1) 5 (1) 2 (2) 2 (1) 0 (1)
  NaOH-EDTA Residue 2 (1) 5 (1) 4 (1) 8 (1) 3 (1) 11 (3) 4 (1)
  NaOH-EDTA Soil 5 (2) 7 (2) 10 (1) 8 (1) 5 (1) 5 (1) 5 (1)
Degradation Mehlich III Soil 3 (4) 3 (3) 3 (1) 15 (2) 5 (5) 3 (1) 1 (4)
  NaOH-EDTA Residue 23 (9) 27 (9) 20 (3) 54 (5) 17 (8) 17 (4) 68 (21)
  NaOH-EDTA Soil 25 (9) 24 (7) 26 (4) 58 (5) 45 (13) 27 (4) 27 (8)
DNA Mehlich III Soil 0 (0) 0 (0) 0 (0) 1 (1) 0 (0) 0 (0) 0 (0)
  NaOH-EDTA Residue 2 (1) 2 (1) 8 (1) 1 (0) 6 (3) 4 (1) 8 (2)
  NaOH-EDTA Soil 3 (1) 7 (2) 2 (1) 11 (1) 3 (1) 3 (0) 3 (1)
Other orthophosphate diesters Mehlich III Soil 1 (1) 1 (1) 2 (1) 4 (1) 1 (1) 1 (1) 1 (2)
NaOH-EDTA Residue 3 (1) 4 (1) 17 (3) 7 (1) 6 (3) 5 (1) 21 (6)
  NaOH-EDTA Soil 11 (4) 10 (3) 16 (2) 21 (2) 9 (3) 8 (1) 5 (1)
Total orthophosphate monoesters Mehlich III Soil 27 (42) 29 (34) 37 (10) 308 (46) 21 (21) 22 (9) 6 (19)
NaOH-EDTA Residue 70 (27) 99 (32) 117 (20) 520 (47) 60 (30) 84 (21) 117 (36)
  NaOH-EDTA Soil 103 (36) 129 (40) 109 (15) 385 (33) 116 (34) 133 (18) 102 (28)
  NaOH-EDTA Difference 33 (9) 31 (7) − 7 (− 5) − 134 (− 15) 55 (5) 48 (− 4) 16 (− 8)
Total orthophosphate diesters Mehlich III Soil 4 (6) 4 (5) 5 (1) 20 (3) 6 (6) 5 (2) 2 (6)
NaOH-EDTA Residue 29 11) 33 (11) 45 (8) 62 (6) 29 (14) 25 (6) 96 (29)
  NaOH-EDTA Soil 39 (14) 42 (13) 49 (7) 90 (8) 57 (17) 37 (5) 35 (10)
  NaOH-EDTA Difference 10 (3) 9 (2) 5 (− 1) 28 (2) 28 (3) 12 (− 2) − 61 (− 20)
Mono:Diester ratio Mehlich III Soil 7.2 7.1 7.0 15.7 3.3 4.4 3.0
  NaOH-EDTA Residue 2.4 3.0 2.6 8.4 2.1 3.3 1.2
  NaOH-EDTA Soil 2.6 3.1 2.2 4.3 2.0 3.6 2.9
  1. Values are concentration in mg kg−1 (percentage of extract P). Degradation is the sum of compounds in the orthophosphate monoester region known to be products of diester degradation during analysis. Monoester 1, 2 and 3 are the sum of peak areas in these regions after subtracting the peak areas for identified P forms. Mono:Diester ratio: the ratio of orthophosphate monoesters to orthophosphate diesters. Total orthophosphate monoesters, total orthophosphate diesters, and the monoester:diester ratio were corrected for degradation. Residue is the residual soil after Mehlich III extraction. Difference is the difference in between the NaOH-EDTA extracts of whole soils and the NaOH-EDTA extracts of the residue after Mehlich III extraction
\