Drecht G van ,
Goossensen FR ,
Hack-ten Broeke MJD ,
Jansen EJ ,
Steenvoorden JHAM
85 p
in Dutch
1991
Toon Nederlands
English Abstract Nine steady state nitrate leaching models have been
tested. Predicted annual leaching rates have been compared with measured
nitrate leaching of field experiments both statistically and visually
(double mass). Five models give satisfactory results for grassland on sandy
soil. No sufficient data are available to test the models for grassland on
clayey soil. None of the teted models can predict the measured nitrate
leaching from silage maize fields on sandy soil satisfactorily. All tested
models underestimate the measured nitrate leaching rates from silge maize
fields. This can be explained by the high mineralization rates of organic N
in these fields that probably have contributed to the nitrate leaching.
Scenario studies have been carried out for cut and grazed grassland, silage
maize and arable land (crop rotation). In a situation of cut grassland on
well drained sandy soil and a N-fertilization level of 400 kg.ha-1.a-1,
five models, that gave satisfactory results in the test, show a wide range
of computed nitrate leaching rates 953 to 172 kg.ha-1.a-1). However most
models compute the same reduction of about 50% of nitrate leaching rates if
the N-fertilization level is decreased to 300 kg. ha-1.a-1 and slurry is
applied in spring by the method of injection instead of
spreading.
