Open access publications in the SLU publication database

Abstract

The aim of the project was to monitor the influence of cultivation on the quality of surface- and grundwater within selected agricultural areas. The project consisted of sixteen experimental fields with measuring devices for regular sampling of drainage water and continous registration of discharge. The experimental fields were included in the farmers normal management and covered various soil types, cropping and ferlilizer regimes. Information concerninge cultivation practices were collected regularly. The size of the fields varied between 4 and 34 ha. Grundwater samples were taken and grondwater pressure measured in eleven fields. Groundwater pressure was meassured once a month and samples were taken every other month. Samples of drainage water were taken every other week, or in some cases every week during periods of large discharge. During the year´of review 1991-92 there was a large variation in nitrogen losses from 1 to 130 kg Tot-N/ha. Twelve of the experimental fields had smaller nitrogen losses compared to average losses during the period 1977/91 (table 1). Mostly this was due to lower nitrogen concentration (table 2 and 3). Also this year most of the fields with lower nitrogen concentrations were cropped during the winter. Phosphorus losses variated from 0,01 to 1,24 kg Tot-P/ha (table 1) and two of the experimental fields had larger losses compared to their long term average. In one of the experimental fields there was a decrease in nitrogen concentration in groundwater. In the remaining fields, the nitrate concentration in groundwater had changed negligible. One of the best fields had nitrate concentrations in groundwater above the headlimit for drinkin water.