Application of the DNDC model to predict N₂O emissions from sandy arable soils with differing fertilization in a long‐term experiment

Abstract

Modeling crop growth and soil N dynamics is difficult due to the complex nature of soil–plant systems. In several studies, the DNDC model has been claimed to be well‐suited for this purpose whereas in other studies applications of the model were less successful. Objectives of this study were to test a calibration and validation scheme for DNDC‐model applications to describe a field experiment with spring wheat on a sandy soil near Darmstadt (SW Germany) using different fertilizer types (either application of mineral fertilizer and straw—MSI; or application of farmyard manure—FYM) and rates (low—MSIL, FYML; and medium—MSIM, FYMM). The model test is based on a model parameterization to best describe the case MSIL and applies this parameterization for a retrospective simulation of the other cases (MSIM, FYML, FYMM) including crop growth and N2O emissions. Soil water contents were not accurately simulated using either the DNDC default values for a loamy sand or for the next finer texture class or using results from the pedotransfer function provided by ROSETTA. After successful calibration of the soil water flow model using a soil texture class that led to the best fit of the measured water content data, grain yield of spring wheat and cumulative N2O emission were slightly underestimated by DNDC and were between 91% and 86% of the measured data. A subsequent calibration of the yields and cumulative N2O emissions from soils of the MSIL treatment gave a good prediction of crop growth and N2O emissions in the MSIM treatment, but a marked underestimation of yields of the FYM treatments. Cumulative N2O emissions were predicted well for all MSI and FYM treatments, but seasonal dynamics were not. Overall, our results indicated that for the sandy soil in Germany, site‐specific calibration was essentially required for the soil hydrology and that a calibration was useful for a subsequent prediction where greater amounts of the same fertilizer were used, but not useful for a prediction with a different fertilizer type.

Assessing the impacts of tillage and fertilization management on nitrous oxide emissions in a cornfield using the DNDC model

“…Overall, the DNDC model could simulate seasonal variations of soil microclimate very well, with correlation coefficients of 0.94 and 0.78 for soil temperature and WFPS, respectively (Figures d–i). Several studies showed that the DNDC model may not work well if WFPS is overestimated [ Ludwig et al ., ; Abdalla et al, ]. In this study, the magnitudes of the daily mean WFPS between simulated and observed were similar, while daily mean soil temperature was slightly underestimated, particularly during the high temperature and drought period (Figures g–i).…”

Assessment of German nitrous oxide emissions using empirical modelling approaches

“…Further, Jungkunst discusses comparably low N 2 O emissions of Haplic Chernozems (SOC accumulation by dryness) confirmed by observations on a Chernozem in southern Germany reported in (Brümmer et al 2010). Ludwig et al (2010) determined annual N 2 O fluxes on a sandy soil with increased SOC caused by long-term application of organic fertilizer. Measured annual N 2 O fluxes did not differ significantly between plots with higher SOC level and control plots.…”

Impact of the size of nitrogen fertiliser application rate on N₂O flux

“…Nitrogen dynamics directly affects crop growth, soil fertility and potential pollution problems such as NH 3 volatilization, soil acidification, increased NO 3 loads of drinking water, eutrophication of surface water and emissions of the greenhouse gas N 2 O (Ludwig et al 2011). Agriculture contributes to the increase in atmospheric N 2 O, accounting for 24% of global annual emissions (IPCC 2007).…”