Nutrient surpluses in agriculture in the Netherlands, 1970-2000
The downward trend in the surplus of nitrogen and phosphorus in agriculture is continuing. A major role was played in 2000 by the reduction of the livestock herd and less use of chemical fertilisers.
Increase in nutrient surpluses between 1970 and 1986
The increase in nutrient surpluses between 1970 and 1986 can mainly be explained by the increase in the size of the livestock herd, pushing up imports of concentrated feed considerably. The main contribution has been from the rise and growth of intensive farming on the sandy soils of the south, east and centre of the country.
In the case of nitrogen, this increase was compounded by the fact that nitrogen levels in feeds also increased sharply in the same period. Moreover, to meet the growing demand for roughage, more nitrogenous fertilisers were used. The rise in the phosphorus surplus due to the growth of the livestock herd has partly been offset by the drop in phosphorus content in concentrated feeds since 1975.
Fall in nutrient surpluses after 1986
The drop in nutrient surpluses since 1986 was mainly the result of the introduction of the Super Levy Decree in 1984 , which resulted in a sharp reduction in the national livestock herd. Nutrient levels in concentrated feeds have also decreased, especially for phosphorus. In addition, the use of nitrogenous fertilisers has dropped considerably: use in 2000 was 32% lower than in 1986.
The wet autumn of 1998 caused a sharp drop in withdrawals from crops (due to crop failures); the nutrient surplus in 1998 was therefore greater than in 1997. The nitrogen surplus in 1999 was 4% lower than in 1998 while the phosphorus surplus remained virtually the same. If all the manure produced in 1998 had been applied that year, the surplus would have increased even more, and would have decreased by the same amount in 1999.
Compared to 1999, the surpluses in 2000 fell faster: 16% for nitrogen and 20% for phosphorus. If the stocks of manure from 1998 had not been applied in 1999, the decreases would have been 14% and 17% respectively. This was mainly the result of a fall in the number of animals in livestock farming (cattle and pigs by 4%) and lower fertiliser use in 2000 (nitrogen 11% and phosphorus 4% lower).
The nitrogen and phosphorus surpluses from agriculture accumulate primarily in the soil. Some nitrogen leaches into the groundwater, while some also evaporates to the air as nitrogen compounds.
