Heavy metal load on agricultural land in the Netherlands, 1980-2001*
| 1980 | 1986 | 1990 | 1995 | 1999 | 2000 | 2001* | ||
| 1 000 kg | ||||||||
| Copper (Cu) | ||||||||
| Gross load | 1 360 | 1 140 | 970 | 800 | 790 | 780 | 780 | |
| of which | manure | 1 050 | 850 | 750 | 700 | 700 | 700 | 700 |
| fertiliser | 150 | 140 | 120 | 50 | 60 | 50 | 50 | |
| wet and dry deposition | 80 | 90 | 50 | 20 | 20 | 20 | 20 | |
| other sources 1) | 80 | 60 | 50 | 30 | 10 | 10 | 10 | |
| among whichsewage sludge | 39 | 38 | 37 | 1 | 1 | 1 | 1 | |
| Withdrawal in crops | 140 | 140 | 130 | 110 | 100 | 100 | 90 | |
| Net load | 1 220 | 1 000 | 840 | 690 | 690 | 680 | 690 | |
| Zinc (Zn) | ||||||||
| Gross load | 2 400 | 2 370 | 2 270 | 2 260 | 2 230 | 2 170 | 2 180 | |
| of which | manure | 1 800 | 1 900 | 1 750 | 2 000 | 2 000 | 1 900 | 1 900 |
| fertiliser | 150 | 160 | 140 | 60 | 50 | 60 | 60 | |
| wet and dry deposition | 260 | 130 | 180 | 100 | 70 | 70 | 80 | |
| other sources 1) | 190 | 180 | 200 | 100 | 110 | 140 | 140 | |
| among which sewage sludge | 115 | 110 | 114 | 4 | 4 | 5 | 5 | |
| Withdrawal in crops | 700 | 750 | 690 | 720 | 570 | 570 | 560 | |
| Net load | 1 700 | 1 620 | 1 580 | 1 540 | 1 660 | 1 600 | 1 620 | |
| Cadmium (Cd) | ||||||||
| Gross load | 16 | 13 | 9 | 6 | 6 | 6 | 6 | |
| of which | manure | 6 | 4 | 4 | 3 | 3 | 3 | 3 |
| fertiliser | 7 | 7 | 4 | 2 | 2 | 2 | 2 | |
| wet and dry deposition | 2 | 1 | 1 | 1 | 1 | 1 | 1 | |
| other sources 1) | 1 | 0 | 0 | 0 | 0 | 0 | 0 | |
| among which sewage sludge | 1 | 0 | 0 | 0 | 0 | 0 | 0 | |
| Withdrawal in crops | 3 | 4 | 3 | 3 | 3 | 3 | 3 | |
| Net load | 12 | 9 | 6 | 3 | 3 | 3 | 3 | |
| Source: Van Eerdt. | CBS/ EDC/Oct02 | |||||||
| 1) Sewage sludge, pesticides, domestic compost and spent mushroom compost. | ||||||||
Developments in heavy metal load on agricultural land
Between 1980 and 2001, the annual net copper load on agricultural land decreased from 0.6 to 0.35 kg Cu/ha; for cadmium there was a drop from approximately 6 to 1.5 g Cd/ha. The net load from zinc remained nearly the same (nearly 1 kg Zn/ha per year). These developments are partially influenced by regulations limiting the amounts of heavy metals allowed in livestock feeds. In addition, fertiliser production now uses purer raw materials.
The primary source of supply is manure. Withdrawal takes place via extraction in crops. Some of the net soil load runs off into groundwater and surface water. The rest accumulates in the soil.
Relevance
A surplus of heavy metals in the soil is undesirable in terms of crop yields and of human and animal health.
