Table 1 Depth resolved phosphorus (P) stocks and the composition of NaOH–EDTA extractable soil P, as assessed by the liquid 31P-NMR spectroscopy of homogenized composite samples (n = 3) of three long-term experimental sites
Management | Depth | P recovery | Phosphonate | Orthophophate | Monoesters | Diesters | Pyrophosphate | Extractable Po | Extractable Pt |
|---|---|---|---|---|---|---|---|---|---|
> 20 ppm | 6.7 to 6.0 ppm | 6.9 to 6.7, 6.0 to 3.5 ppm | 2 to − 2 ppm | − 4.3 ppm | |||||
cm | % | kg ha−1 (%) | |||||||
Dahlem | |||||||||
Control | 0–30 | 30 | 0.0 (0) | 627 (80) | 144 (18) | 4.5 (0.6) | 6.2 (0.8) | 148 (19) | 781 |
30–50 | 19 | 0.0 (0) | 191 (96) | 8 (4) | 0.0 (0) | 0.0 (0) | 8 (4) | 199 | |
70–90 | 10 | 0.0 (0) | 172 (100) | 0.0 (0) | 0.0 (0) | 0.0 (0) | 0 | 172 | |
Mineral + organic P | 0–30 | 45 | 0.0 (0) | 989 (85) | 162 (14) | 3.3 (0.3) | 6.8 (0.6) | 166 (14) | 1162 |
30–50 | 51 | 0.0 (0) | 410 (98) | 10 (2) | 0.0 (0) | 0.0 (0) | 10 (2) | 420 | |
70–90 | 15 | 0.0 (0) | 186 (100) | 0.0 (0) | 0.0 (0) | 0.0 (0) | 0 | 186 | |
Freising Dürnast | |||||||||
Control | 0–30 | 57 | 0.0 (0) | 825 (67) | 392 (32) | 6.8 (0.6) | 9.2 (0.7) | 398 (32) | 1233 |
30–60 | 40 | 3.5 (0.4) | 477 (50) | 461 (49) | 1.9 (0.2) | 6.2 (0.7) | 466 (49) | 949 | |
60–90 | 47 | 0.0 (0) | 557 (62) | 339 (38) | 0.0 (0) | 4.9 (0.5) | 339 (38) | 901 | |
Mineral + organic P | 0–30 | 64 | 3.1 (0.2) | 1187 (72) | 442 (27) | 5.8 (0.3) | 10.2 (0.6) | 451 (27) | 1648 |
30–60 | 37 | 2.2 (0.2) | 514 (52) | 454 (46) | 3.7 (0.4) | 5.3 (0.5) | 460 (47) | 979 | |
60–90 | 48 | 0.0 (0) | 787 (68) | 358 (31) | 0.0 (0) | 4.9 (0.4) | 358 (31) | 1150 | |
Bad Lauchstädt | |||||||||
Control | 0–30 | 39 | 0.0 (0) | 336 (46) | 386 (53) | 2.7 (0.4) | 8.4 (1.1) | 388 (53) | 733 |
30–60 | 28 | 0.0 (0) | 117 (39) | 177 (59) | 3.4 (1.1) | 1.0 (0.3) | 180 (60) | 299 | |
60–90 | 11 | 0.0 (0) | 54 (52) | 50 (48) | 0.0 (0) | 0.0 (0) | 50 (48) | 103 | |
Mineral + organic P | 0–30 | 56 | 0.0 (0) | 1554 (82) | 328 (17) | 9.4 (0.5) | 9.0 (0.5) | 338 (18) | 1901 |
30–60 | 39 | 0.0 (0) | 750 (71) | 299 (28) | 5.7 (0.5) | 4.0 (0.4) | 305 (29) | 1059 | |
60–90 | 35 | 0.0 (0) | 384 (67) | 187 (33) | 1.3 (0.2) | 0.0 (0) | 189 (33) | 572 | |