Table 1 The N-P-K balance for mainland Portugal cropland. The flow share is shown in percentage.
N-P-K flows (Mg) | N | P | K | |||
|---|---|---|---|---|---|---|
Outputs | % | % | % | |||
Harvests (Ho) | 38 828 | (19.0) | 6 358 | (30.6) | 14 192 | (13.8) |
Cropped or grazed straw (So) | 19 081 | (9.3) | 3 287 | (15.8) | 17 918 | (17.4) |
Cropped or grazed weeds – crops (Wo) | 42 275 | (20.7) | 4 004 | (19.3) | 28 470 | (27.7) |
Cropped or grazed weeds – fallow (Go) | 29 514 | (14.4) | 2 904 | (14.0) | 20 650 | (20.1) |
Woody crops pruning (Po) | 2 704 | (1.3) | 369 | (1.8) | 2 635 | (2.6) |
Leaching and runoff (Lo) | 19 360 | (9.5) | 0 | (0) | 11 256 | (11.0) |
Erosion (Eo) | 0 | (0) | 3 830 | (18.5) | 7 645 | (7.4) |
N emissions (Vo) | 52 692 | (25.8) | 0 | (0) | 0 | (0) |
Sum | 204 455 | (100) | 20 753 | (100) | 102 767 | (100) |
Inputs | ||||||
Seeds (Si) | 3 788 | (2.0) | 614 | (1.3) | 1 167 | (1.1) |
Manure (Mi) | 28 528 | (14.8) | 5 554 | (11.8) | 14 007 | (12.9) |
Field excretions (Ei) | 30 357 | (15.7) | 4 992 | (10.6) | 15 438 | (14.2) |
Other biomass entries (Bi) | 7 284 | (3.8) | 1 159 | (2.45 | 9 719 | (9.0) |
Chemical fertilizers (Fi) | 37 918 | (19.7) | 27 752 | (58.7) | 4 916 | (4.5) |
Litterfall (LFi) | 3 275 | (1.7) | 280 | (0.6) | 2 944 | (2.7) |
Rainfall (Ri) | 22 622 | (11.7) | 1 126 | (2.4) | 9 118 | (8.4) |
Irrigation (Ii) | 5 569 | (2.9) | 152 | (0.3) | 9 546 | (8.8) |
Soil weathering (Wi) | 0 | (0) | 5 628 | (11.9) | 41 719 | (38.4) |
Symbiotic N fixation - cultivated legumes (Li) | 8 355 | (4.3) | 0 | (0) | 0 | (0) |
Symbiotic N fixation - wild legumes (LWi) | 27 490 | (14.3) | 0 | (0) | 0 | (0) |
Non-symbiotic N fixation (Oi) | 17 589 | (9.1) | 0 | (0) | 0 | (0) |
Sum | 192 774 | (100) | 47 257 | (100) | 108 575 | (100) |
Balance | ||||||
(Mg) | −11 681 | 26 503 | 5 808 | |||
(kg.ha−1.yr−1) | −2, 1 | 4, 7 | 1, 0 | |||
