W. Aufhammer et al., NITROGEN UPTAKE AND NITROGEN RESIDUALS OF WINTER OILSEED RAPE AND FALLOUT RAPE, Journal of agronomy and crop science, 172(4), 1994, pp. 255-264
The objective of the investigation was a study of the relationship bet
ween seed dry-matter production and vegetative dry-matter production i
n oil-seed rape crops and their dependence on the production condition
s. In addition to the relationship between the N-uptake during the veg
etation period and the N-residue after harvest was of major interest.
Furthermore the potential for N-uptake in fallout rape was measured. O
ver two vegetation periods factorial field experiments with winter oil
-seed rape, cv. Lirabon, different drilling techniques and different n
itrogen fertilization levels were tested. Measured traits were: the dr
y-matter accumulation including root mass and fall-off leaf-material m
ass, the N-uptake of both the oil-seed crops and the fallout rape stan
ds, and, simultaneously, the soil NO3-N content. Finally the harvest i
ndices and the N-harvest indices were calculated. Combined with a N-up
take of up to 330 kg N/ha, oil-seed rape crops produced up to 200 dt d
ry matter/ha. At seed yield levels of 33 dt/ha (d.m.), harvest indices
varied from 0.14-0.23 and N-harvest indices varied from 0.30-0.50. As
a result of the residue of vegetative plant material at harvest, leaf
losses before harvest and the soil NO3-N-contents at harvest up to 27
5 kg N/ha remained in the field. After the harvest of oil-seed rape, t
he soil NO3-N-contents were quickly reduced by emerging and growing fa
llout rape stands. However, following soil-preparation measures in the
autumn, a continuous rise in the soil NO3-N-content was observed.