Abstract

Nutrient leaching from clay soils can show extreme temporal and spatial variation. Using an optical sensor (hourly data storage), a Swedish field with vermiculite clay was monitored for water flow (Qexpressed in mm), turbidity values (TURB), and nitrate-nitrogen concentrations (CNO3N, mg L-1) in four hydrological years representing different cropping/soil management regimes. Mean TURB-Q slope (1300) decreased in the order: ploughed soil > winter wheat > unfertilized fallow > winter wheat after drainage system renovation + structure-liming of topsoil and backfill, estimated in the initial phase from 16 selected autumn events. A similar ranking was found for variability in turbidity relative to that in discharge (CVT/CVQ) in the entire autumn. Mean CNO3N-Q slope (=2) was significantly lower under fallow than in the three cropping systems (7-32), confirming results from adjacent experimental plots. A spring-period had no snow cover or intensive rain, butin situmonitoring revealed that nutrient leaching was still substantial. Particulate- and dissolved reactive phosphorus, and nitrate-nitrogen leaching was estimated reasonably well (less than 8% difference) based onin situhigh-frequency resolution measurements, compared with laboratory analysis of weekly composite samples. Accurate assessment ofC-Qrelationships in agricultural drainage water across temporal and spatial scales is therefore important.

Keywords

C-Qslope; DRP; drainage system; hysteresis; NO3N; turbidity

Published in

Acta Agriculturae Scandinavica, Section B - Soil and Plant Science
2020, volume: 70, number: 5, pages: 392-403

Authors' information