ISHS Acta Horticulturae 627: XXVI International Horticultural Congress: Toward Ecologically Sound Fertilization Strategies for Field Vegetable Production
NITROGEN UPTAKE IN A BROCCOLI CROP. 1: NITROGEN DYNAMICS ON A RELATIVE TIME SCALE |
| Author: | I.M. Vågen |
| Keywords: | Brassica oleracea var. italica, Critical %N, Nmin, Variety, Yield |
| Abstract:
Broccoli has a short growing period and a high demand for nitrogen. To avoid N leaching from soil and ensure better economy for the grower, it is essential to choose the right time for N application. We present nitrogen uptake curves for three fertilizer N levels viewed on a relative time scale from planting to harvest, based on six field experiments with broccoli in southern Norway in 1999 and 2001. Total fertilizer N was split in four applications, at planting and 2, 4 and 6 weeks after planting. Plant N and soil inorganic N (Nmin) were sampled at regular intervals throughout the whole growing period. At the highest fertilizer N level, 240 kg N ha-1 applied, N did not appear to be limiting nor excessive. The N uptake at this fertilizer level appears to give a good impression of the nitrogen requirement of broccoli plants through the growing period. N concentration is compared to the critical %N values from N_ABLE, used for modelling N dynamics in vegetable crops. The early maturing cv. Milady F1 did not accumulate N earlier than the main cv. Marathon F1. Data show that rapid N uptake in broccoli starts about the same time as the small heads just become visible to the eye. This could be a practical indicator for timing of an additional fertilizer N application. | |
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