ISHS Acta Horticulturae 571: Workshop Towards and Ecologically Sound Fertilisation in Field Vegetable Production
A SIMPLE MODEL TO PREDICT N MINERALISATION OF GREENHOUSE SOILS |
| Authors: | J. Salomez, K. D'Haene, G. Hofman, I. Vandevelde |
| Keywords: | soil organic matter, incubation experiments, N mineralisation kinetics, rate constant |
| Abstract:
The formulation of a correct N fertilisation advice, besides a measurement of Nmin at the start of the growing period, mainly depends on the possibility to predict the N mineralisation out of soil organic matter. This study aimed to model the N mineralisation of greenhouse soils, using both easily available and easily measurable parameters. Two laboratory incubation experiments were set up. The first incubation experiment allowed to deduct a zero-order model, Nt = kt, in which Nt = N mineralised [kg N ha-1], k = N mineralisation rate constant [kg N ha-1 day-1] and t = time [days], whereas the temperature dependence of the N mineralisation rate constant was deduced out of the second incubation experiment. The N mineralisation rate constant further depends on the N mineralisation potential of the soil and on the 'soil's age', i.e. being the time the soil has been glass-covered, eventually leading to the following simple N mineralisation model: Nt = (-9.965 + 0.104 NKCl + 0.336 T + 0.095 O)t, with NKCl = Nmin in a hot KCl-extract (100°C) [kg N ha-1], T = temperature [°C] and O = soil's age [years]. Though the via the model calculated (kmod) and experimentally obtained (kexp) N mineralisation rate constants were closely related and a linear relationship was found kmod = 0.872 kexp (R2 = 0.719,  <0.01), further research is necessary to evaluate this model in-situ.
In the long run it will be incorporated into a nitrogen fertilisation advice system for greenhouse crops.
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