NITROGEN UPTAKE AND NITROGEN LOSSES IN FIELD TRIALS WITH CARROTS

The aim of the investigations presented in this paper is to demonstrate the influence of nitrogen supply on nitrogen uptake, N_min value at the end of cultivation period, and nitrogen losses in carrot production.
The results of 13 field trials were used to calculate an N balance and to indicate N losses.
The inputs of the N balance were the N_min value at the beginning of cultivation, N fertilization, atmospheric N deposition and net nitrogen mineralization.
The outputs were the N uptake by plants and the N_min value at the end of cultivation.
The net nitrogen mineralization was calculated by the CArbon Nitrogen DYnamics Model “CANDY” (Franko 1989).

The results showed that an increase of N supply from 120 to 390 kg/ha was related to

• a declining percentage (from 95 to 70%) of N used by plant uptake,

• an increase of the N_min value from about 10 to 40 kg*ha^-1 *60cm^-1 at the end of cultivation period, and

• an increase of the balance deficit including N losses from about 0 to 18% of N supply.

Linear regression indicated that 75% of variation in N uptake was caused by variation of N supply including all components of N balance input.
Regression results were compared with the recommendation of the “KNS” system for N fertilization of carrot and for calculating N mineralization.
Both the regression method and the “KNS” system recommended give nearly the same N-supply to get an N uptake of 160 kg/ha.

Ecological aspects of Vegetable Fertigation in Integrated crop Production in the Field

J. Rühlmann, Y. Kuzyakov, B. Geyer

nitrogen balance, simulation model, mineralization, carrots

https://doi.org/10.17660/ActaHortic.1996.428.10