• Praktijkproef nutrientenbalans. Nutrientenbelasting van het oppervlaktewater via drainagewater van akkerbouwpercelen van zavelgrond

      Hoekstra JR; Eertwehg GAPH van den; Meinardi CR; LBG (Provincie ZeelandHoogheemraadschap RijnlandWageningen Universeit, 1999-08-20)
      Measurements on the emission of nutrients by tile drainage of arable land with a loamy soil were executed at the Rusthoeve-farm in Colijnsplaat. The catchment areas of 4 tile drains (1.32 ha) and the receiving ditch (9.57 ha) were intensily and continuously monitored concerning the discharge of water, chloride and nutrients (N, P). Elaboration of two years of measurements and data on crops and fertilizer use resulted in water and solute balances. The water balances show that upward seepage is nearly absent and also that overland flow is only a marginal discharge component. Preferential flow of water and nutrients may occur through macropores in the topsoil. Roughly 25% of the water discharge via the tile drainage has resided less than 1 year in the soil, 45% less than 2 years, 65% less than 3 years, 80% less than 4 years and 20% more than 4 years. The concentrations of total-Nitrogen vary between less than 1 to 29 mg.l-1 being on the average 4 mg.l-1. Nitrogen-concentrations in ditch water vary between 1 and 27 mg.l-1 , having an average of 6 mg.l-1 , the variations corresponding largely to varying nitrate concentrations. The highest nitrogen concentrations in drain- and ditch water were measured during periods of high water discharge. Total-Phosphate concentrations in drainage water vary from 0.05 to 1.22 mg.l-1 with an average of 0.21 mg.l-1. Ditch concentrations vary between 0.03 and 1.64 mg.l-1 , being, on the average, 0.31 mg.l-1.