Evaluation of the DNDC Model to Estimate Soil Parameters, Crop Yield and Nitrous Oxide Emissions for Alternative Long-Term Multi-Cropping Systems in the North China Plain

Mohamed Abdalla,Xiaotong Song,Xiaotang Ju,Pete Smith

doi:10.3390/agronomy12010109

Abstract

Optimizing crop rotations is one of the proposed sustainable management strategies for increasing carbon sequestration. The main aim of this study was to evaluate the DeNitrification-DeComposition (DNDC) model for estimating soil parameters (temperature, moisture and exchangeable NO3− and NH4+), crop yield and nitrous oxide (N2O) emissions for long-term multi-cropping systems in Hebei, China. The model was validated using five years of data of soil parameters, crop yields and N2O emissions. The DNDC model effectively simulated daily soil temperature, cumulative soil nitrogen and crop yields of all crops. It predicted the trends of observed daily N2O emissions and their cumulative values well but overestimated the magnitude of some peaks. However, the model underestimated daily water filled pore space, especially in dry seasons, and had difficulties in correctly estimating daily exchangeable NO3− and NH4+. Both observed and simulated cumulative N2O results showed that optimized and alternative cropping systems used less nitrogen fertiliser, increased grain yield and decreased N2O emissions compared to the conventional cropping system. Our study shows that although the DNDC model (v. 9.5) is not perfect in estimating daily N2O emissions for these long-term multi-cropping systems, it could still be an effective tool for predicting cumulative emissions.

Highlights

Agricultural land accounts for about 13% of global soil greenhouse gas (GHG) emissions and one-fifth of the annual increase in radiative forcing
The average measured temperature was 17.8 ◦C, root mean square error (RMSE) ranged from 3.73 ◦C to 4.36 ◦C; normalized RMSE (nRMSE) ranged from 19 to 24% and d values ranged from 0.92 to 0.95 (Table 1)
The correct estimation of soil temperature by the DNDC is important for a reliable model-estimation for crop yield and N2O emissions as the soil temperature influences decomposition of soil organic carbon, soil microorganism activities and plant growth [46,47]

Summary

Introduction

Agricultural land accounts for about 13% of global soil greenhouse gas (GHG) emissions and one-fifth of the annual increase in radiative forcing. There are many management mitigation strategies to sequester carbon (C) or reduce emissions from soils such as reduced N fertilisation, reduced water irrigation, applying non-inversion tillage and optimizing crop rotations [7,8]. Many factors are responsible for regulating N2O emissions during the processes of nitrification and denitrification Among others, these factors include soil N concentration, N fertiliser application amounts, soil temperature, soil moisture and land use and management [16]. Soil microorganisms responsible for N2O consumption or production are influenced by these crop rotations and their associated higher soil organic matter (SOM) [28] They can convert N2O to N2 (i.e., complete denitrification) and thereby reduce the emissions of N2O from soils [29,30]. The main aim of this study was to evaluate the DNDC model for simulating soil parameters, crop yield and N2O emissions for conventional, optimal and alternative long-term multi-cropping systems in Hebei, China

Objectives

Methods

Results

Conclusion