Calibration and validation of the DNDC model to estimate nitrous oxide emissions and crop productivity for a summer maize-winter wheat double cropping system in Hebei, China

Mohamed Abdalla, Xiaotong Song, Xiaotang Ju, CFE Topp, Pete Smith

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    Abstract

    The main aim of this paper was to calibrate and evaluate the DeNitrification-DeComposition (DNDC) model for estimating N2O emissions and crop productivity for a summer maize-winter wheat double cropping system with different N fertilizer rates in Hebei, China. The model’s performance was assessed before and after calibration and model sensitivity was investigated. The calibrated and validated DNDC performed effectively in estimating cumulative N2O emissions (coefficient of determination (1:1 relationship; r2) = 0.91; relative deviation (RD) = -13 to 16%) and grain yields for both crops (r2 = 0.91; RD = -21 to 7%) from all fertilized treatments, but poorly estimated daily N2O patterns. Observed and simulated results showed that optimal N fertilizer treatment decreased cumulative N2O flux, compared to conventional N fertilizer, without a significant impact on grain yields of the summer maize-winter wheat double cropping system. The high sensitivity of the DNDC model to rainfall, soil organic carbon and temperature resulted in significant overestimation of N2O peaks during the warm wet season. The model also satisfactorily estimated daily patterns/ average soil temperature (o C; 0-5 cm depth) (r2 = 0.88 to 0.89; root mean square error (RMSE) = 4o C; normalized RMSE (nRMSE) = 25% and index of agreement (d) = 0.89-0.97) but under-predicted water filled pore space (WFPS; %; 0-20 cm depth) (r2 = 0.3 to 0.4) and soil ammonium and nitrate (exchangeable NH4+ & NO3-; kg N ha-1; r2 = 0.97). With reference to the control treatment (no N fertilizer), DNDC was weak in simulating both N2O emissions and crop productivity. To be further improved for use under pedo-climatic conditions of the summer maize-winter wheat double cropping system we suggest future studies to identify and resolve the existing problems with the DNDC, especially with the control treatment.
    Original languageEnglish
    Article number114199
    JournalEnvironmental Pollution
    Volume262
    Early online date25 Feb 2020
    DOIs
    Publication statusPrint publication - Jul 2020

    Bibliographical note

    ©2020 Elsevier Ltd. All rights reserved

    Keywords

    • Calibration
    • Crop productivity
    • DNDC model
    • Nitrous oxide
    • Summer maize-winter wheat double cropping system
    • Validation

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