Speaker
Description
Introduction: Diversified and legume based crop rotations, particularly when including catch and cover crops, can increment soil organic matter (SOM) and nitrogen (SON) stocks, capture excess nitrogen after harvest of main crops, and biologically fix N2 from the atmosphere. Thus, greenhouse gas (GHG) emissions can potentially be minimised by capturing additional CO2 and by reducing the demand for synthetic N fertiliser, the main contributor to N2O emissions in many conventional planting systems. However, farmers tend to be hesitant to test new crop rotations without evidence of positive effects on crop yields and climate. Process-based plant-soil models can simulate nutrient cycles, plant growth and GHG emissions, accounting for site-specific soil properties, weather, and plant related processes. Life cycle assessment (LCA), fed with data from such process-based models can improve GHG flux estimations compared to commonly used tiers 1 and 2 (static emission factors) to the potentially more accurate tier 3 level. Thus, coupling a process-based model with LCA can enhance understanding the effects of crop rotations on GHG emissions and help farmers to explore promising crop rotations on a knowledge base.
The Julius Kühn Institute’s KlimaFFolgen project is developing such a coupled tool in order to provide
a) a user friendly web application for practitioners to explore crop rotations on selected plots;
b) a scientific tool for regional assessment of trends including projections under different climate scenarios (RCPs).
Materials and Methods: Our decision support tool builds on the SYNOPS platform (https://synops.julius-kuehn.de), originally designed for spatially explicit risk assessment of pesticide applications. Once the user selects a plot, historical or future daily weather data on a 1km2 grid (German Weather Service) as well as soil properties (BÜK 200 by BGR) are assigned to this location. Typical regional crop rotations (remote-sensing based; Preidl et al. 2020) as well as default management data are suggested, but can be overwritten by the user.
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Fig. 1. The KlimaFFolgen decision support tool integrating process-based soil-crop model and LCA
We use DSSAT 4.8 to simulate plant growth and soils, including an implementation of DayCENT for SOM dynamics. Our partial LCA covers the system from cradle to farm gate over the entire crop rotation, representing several agronomic and environmental indicators.
Results: A tour through the web application demonstrates how data are entered and processed in the decision support system.
Plant growth in our approach on crop rotations has already been validated for SouthWest Germany (Attia et al. 2024; Marohn et al. 2023). First results of a specific validation of N2O emissions, simulated by DSSAT-DayCENT for seven sites across Germany, are presented for the first time at the ESA conference. SOC stocks, GHG emissions and crop yields as well as leached NO3- (agronomic / environmental indicator) are simulated for a real baseline and compared to hypothetical scenarios with additional legumes and reduced mineral fertiliser levels.
Discussion: The decision support tool can assess effects of improved crop rotations and management on C and N dynamics relevant to plant nutrition and climate change. The system will enable more detailed analyses of crop rotations and management, e.g. on benefits, trade-offs and permanence of measures under different rotations including catch and cover crops, improved synchronisation and dosage of fertiliser application. We also discuss expectations of the different target groups – e.g. user friendliness, communication of uncertainties – and hardware / software requirements for parallelised mass runs.
References:
Attia, A., Marohn, C., Shawon, A.R., de Kock, A., Strassemeyer, J., Feike, T. 2024. Do Rotations with Cover Crops Increase Yield and Soil Organic Carbon?—A Modeling Study in Southwest Germany. Preprint. https://ssrn.com/abstract=4668747.
Marohn, C. Attia, A., de Kock, A., Horney, P., Daehmlow, D., Fussek, P., Strassemeyer, J., Feike, T. 2023. A web application for climate-friendly crop rotations integrating process-based plant-soil models and life cycle assessment. Presentation GPW Conference, Göttingen, 4.-6. October 2023.
Preidl et al. 2020. Introducing APiC for regionalised land cover mapping on the national scale using Sentinel-2A imagery. doi.org/10.1016/j.rse.2020.111673.
| Keywords | Crop model; LCA; crop rotation; GHG emissions; GHG emissions |
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