Development in nutrient balances in Danish agriculture 1980–2004

摘要

A farm-gate nutrient balance showed that the surpluses per hectare fell from 175 to 123 kg N, from 29 to 13 kg P and from 61 to 32 kg K from 1979/80 to 2003/04. Consequently, the nutrient use efficiency (total output in % of total input) increased for N from 20% in 1979/80 to 37% in 2003/04, for P from 23% to 52% and for K from 18% to 43%. Parallel to the peak in surplus of N around 1980, elevated nitrogen concentrations were observed in ground and marine waters. A series of agro-environmental action plans were initiated, and the discharge of N to Danish coastal waters was reduced, though less than the reduction in surplus and losses from agriculture. In contrast to N, the reduction in P surplus was not reflected in any reduction in discharge of P from agriculture during the last two decades. A farm-gate account of N surplus is a reasonable indicator of potential N loss, whereas loss of P is mainly related to the soil P saturation level and to specific loss events. By preparing accounts for sub-sectors such as the arable and animal production sectors or for products within these sectors, farm-gate nutrient balances show the development in agricultural production, in addition to the trend in potential environmental impacts. Nutrient balances may thus link the environmental aspect to the economic aspect of agricultural production and assist in the monitoring of the sustainability of agriculture.