Simulation of net N immobilisation and mineralisation in substrate-amended soils by the NCSOIL computer model (original) (raw)

Abstract

The capability of the NCSOIL computer model to simulate the effects of residue fractions on mineralisation-immobilisation turnover was evaluated. Heterogeneous organic substrates were represented in the model by three Van Soest pools, decomposing at different rates. Dried and ground wheat straw, sunflower stalks, wheat stubble and sheep manure (5.22 g kg–1 soil) were respectively added to a Chromic Calcixerert and aerobically incubated for 224 days at 22±2 °C and 75% field capacity. The CO2 evolution rates peaked shortly after the C amendments were added, with the highest rate in the sunflower- stalk-amended soils. The addition of organic substrates induced rapid N immobilisation. Net mineralisation was detected earliest in the sunflower-stalk treatment (day 14), while soils with the other amendments showed no net N mineralisation until day 52. The NCSOIL model was calibrated for this soil with CO2 and inorganic N data from the control soil, yielding a χ2 value of 0.011. The overestimation by the model of the C mineralisation data in the case of C-amended soils clearly showed that the concept of three Van Soest pools, decomposing independently at a specific rate constant, is not valid. A retardation factor, that was related to the lignin content of the decomposing material, was introduced into the model. After its introduction the model satisfactorily simulated the C mineralisation rates. However, for all plant residues, N mineralisation was underestimated towards the end of the incubation period. In the case of the soil amended with sheep manure, there was a large discrepancy between simulated and experimental N mineralisation-immobilisation kinetics, suggesting a different allocation of N in animal manure to N-containing fractions compared to that of plant residues. The results indicated that a N fractionation procedure for organic residues should be tested and incorporated into the model.

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Authors and Affiliations

  1. University of Gent, Faculty of Agricultural and Applied Biological Sciences, Coupure Links 653, B-9000 Gent, Belgium e-mail: oswald.vancleemput@rug.ac.be, Tel.: +32-9-2646002, Fax: +32-9-2646242, , , , , , BE
    M. Corbeels, G. Hofman & O. Van Cleemput

Authors

  1. M. Corbeels
  2. G. Hofman
  3. O. Van Cleemput

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Received: 9 January 1998

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Corbeels, M., Hofman, G. & Van Cleemput, O. Simulation of net N immobilisation and mineralisation in substrate-amended soils by the NCSOIL computer model.Biol Fertil Soils 28, 422–430 (1999). https://doi.org/10.1007/s003740050515

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