The effect of phosphorus application and balance on concentrations in streams from agricultural dominated catchments in Norway

摘要

Elevated phosphorus (P) use is a worldwide problem for the sustainability of agricultural production with consequences for both food production and water quality. The objective of this paper was to investigate the effect of P application and P balance on stream P concentrations in different production systems of Norwegian agriculture. The average application of P in the studied catchments ranged from 21 to 53 kg P ha(-1) yr(-1), including the P application in both mineral fertiliser and manure for the monitoring periods (16-20 years). The highest P application was found in a catchment with high livestock density, and potato and vegetable production. This catchment also showed the highest P balance (applied P minus P removed with yields) of 26 kg P ha(-1) yr(-1) on average, and also a very high soil P status (P-AL). The P balance for all other catchments ranged from 3 to 13 kg P ha(-1) yr(-1). For all catchments, the average application of mineral P fertiliser decreased during the monitoring period, especially during the last 2-3 years. However, total P application increased in three catchments due to increased livestock density and manure P application. Average concentrations of total P in the streams varied from 65 to 392 mu g L-1. The highest concentration was measured in the stream from the catchment with highest P balance and soil P status. The concentrations of dissolved reactive P varied from 27 to 63 mu g L-1 with the highest concentration measured from an area with intensive livestock production. Reducing P application and soil P status to the minimum level for crop growth is important for the environmental quality of surface waters