Onderzoek aan drainwater in de kleigebieden van Nederland; Deel II: Interpretatie van de gegevens
Citations
Altmetric:
Series / Report no.
Open Access
Type
Report
Language
nl
Date
1997-11-30
Research Projects
Organizational Units
Journal Issue
Title
Onderzoek aan drainwater in de kleigebieden van
Nederland; Deel II: Interpretatie van de gegevens
Translated Title
Research on tile drainage water; Part II:
Interpretation of data
Published in
Abstract
Dit onderzoek in de periode 1992-1995 omvatte een twee-
of meermalige bemonstering van water uit drains en sloten van circa 30
boerderijen verspreid over de zeekleigebieden van Nederland. De
samenstelling van het drainwater is gebruikt voor een beschrijving van de
effecten van het weer (neerslag min verdamping) en de verdeling van de
verblijftijden van het water in de bodem. De uitspoeling van nitraat door
drains onder bouwland is bij benadering een lineaire functie van de
stikstof-belasting aan maaiveld, waarbij de aard van de bodem (zand, zavel,
klei) en de grondwater-stand (Gt) bepalende factoren zijn. De uitspoeling
bij diepe grondwaterstanden is 10 tot 25% van de belasting, nadat rekening
is gehouden met een reductie als gevolg van de oxidatie van sulfiden en/of
het voorkomen van kwel. De uitspoeling is voor grasland kleiner dan voor
bouwland. Bij grasland (en de teelt van graszaad) is de uitspoeling van
nitraat bij benadering een lineaire functie van de belasting, na aftrek van
opname door het gewas, bodemtype en Gt. Uit het onderzoek van het
drainwater in de kleigebieden blijkt dat de uitspoeling van fosfaat relatief
constante concentraties aan ortho- en totaal-fosfaat oplevert, die
verschillen voor bouwland (0.10 mg.l-1 als ortho-P), voor recent grasland
(0.20 mg.l-1 als ortho-P) en voor oud permanent grasland (0.40 mg.l-1
als ortho-P).
The investigations of the tile drain water composition in areas with a clayey soil consisted of taking two or more samples of drain water at 30 farms in the sea-clay regions of the Netherlands from 1992 to 1995. The drain-water composition was used to describe the significant effects of the weather (precipitation minus evapotranspiration) and the distribution of travel times in the soil on the drain-water composition. The effect of nitrate leaching from arable land (and orchards) provided with tile drains assumed linear relationships with the N load, depending on the texture of the soil (sand, loam, clay) and groundwater depth (Gt). The N leaching was 10% to 25% of the load for deep-water levels, after taking into account a possible reduction by the oxidation of sulfide compounds, or the occurrence of seepage water in drain discharge. The leaching of nitrate from grassland is generally less than from arable land. Reduced leaching was also observed after growing grass seedlings on arable land in the year before sampling. The leaching from grassland is a function of the load (after subtracting uptake by vegetation), of the soil type and of groundwater depth. The leaching of phosphate in clay regions has no direct relationship to surface loading, yet the crops grown differed. Phosphate concentrations in drain water discharged from arable land had relatively constant values of 0.10 mg.l-1 (as ortho-P). Leaching from recent grassland was roughly 0.20 mg.l-1 (as ortho-P), while leaching from older permanent meadows had a relatively high value of 0.40 mg.l-1 (as ortho-P) and greater. The number of cases investigated was too small to make significant conclusions on phosphate leaching from grassland.
The investigations of the tile drain water composition in areas with a clayey soil consisted of taking two or more samples of drain water at 30 farms in the sea-clay regions of the Netherlands from 1992 to 1995. The drain-water composition was used to describe the significant effects of the weather (precipitation minus evapotranspiration) and the distribution of travel times in the soil on the drain-water composition. The effect of nitrate leaching from arable land (and orchards) provided with tile drains assumed linear relationships with the N load, depending on the texture of the soil (sand, loam, clay) and groundwater depth (Gt). The N leaching was 10% to 25% of the load for deep-water levels, after taking into account a possible reduction by the oxidation of sulfide compounds, or the occurrence of seepage water in drain discharge. The leaching of nitrate from grassland is generally less than from arable land. Reduced leaching was also observed after growing grass seedlings on arable land in the year before sampling. The leaching from grassland is a function of the load (after subtracting uptake by vegetation), of the soil type and of groundwater depth. The leaching of phosphate in clay regions has no direct relationship to surface loading, yet the crops grown differed. Phosphate concentrations in drain water discharged from arable land had relatively constant values of 0.10 mg.l-1 (as ortho-P). Leaching from recent grassland was roughly 0.20 mg.l-1 (as ortho-P), while leaching from older permanent meadows had a relatively high value of 0.40 mg.l-1 (as ortho-P) and greater. The number of cases investigated was too small to make significant conclusions on phosphate leaching from grassland.
Description
Publisher
Sponsors
DGM/DWL