Speakers
Description
Introduction
Since the 2000’s, innovative cropping systems have been designed and tested at INRAE in "system experiments", with the constraint of drastically limiting or even eliminating the use of pesticides. To this end, these systems are based on the principles of agroecology, mobilizing - in conjunction with a variety of cropping techniques - the services provided by increased biological diversity, which is mainly expected to result in biological regulation of pests and diseases. Although multi-performance was generally sought in these system experiments, high nitrogen (N) performance was not a central objective in their design. In NExSys research project, we therefore hypothesize that the nitrogen performance of these systems can be improved, both in terms of plant nutrition and environmental impacts. One step to test this assumption is the assessment of the N efficiency and N losses in these systems.
Materials, methods
In about 10 system experiments, we collected different types of data: crop sequences and cropping techniques (sowing and harvest dates, mineral and organic fertilization, tillage interventions), soil characteristics and meteorological data. We also collected measurements as soil mineral N and plant N at different dates.
We then applied several tools to the cropping systems according to our different purposes:
- SyNE (Godinot et al, 2014) to assess the N efficiency
- SyNB to assess the global N balance
- Syst’N® (Parnaudeau et al 2012, Bedu et al., 2023) to assess and make the diagnosis of N losses towards environment
Results and discussion
The first results were methodological, as expected. SyNE results showed that for systems with low inputs and outputs (low production), the efficiency was very uncertain and sometimes aberrant because of the uncertainty associated to the calculation of the stocks of soil organic N. In systems with higher N fluxes, SyNE and SyNB allowed identifying soil N mining situations. Syst’N® results were correct when compared to N measurements in plant and soil for simple systems (without intercrops in particular). In systems with high N organic restitutions (manure application and pastures), soil N mineralization had to be calibrated to provide good results. In diversified systems with no or shallow tillage systems, Syst’N® still requires additional calibration or even modifications to take account of the complexity of the processes influencing N losses.
Work is ongoing and more detailed results will be presented in the poster.
Acknowledgements
We thank S Nowak and E Pelhate (OasYs), MN Mistou (La Cage), T Puech (Mirecourt), F Ferchaud and G Vitte (ACBB Mons), V Cellier (ResOpest) and AS Voisin, S Cordeau, B Nicolardot and V Deytieux for providing the data of the different trials. We also thank the AgroEcoSystem department of INRAE for their financial support.
References
Bedu M., Lefèvre L., Dupont A., Dubrulle P., Reau R., Debaeke P., Guinet M., Jeuffroy M.-H., Maury P., Schneider A. ... Parnaudeau V. (2023-11). Adding a diversity of legumes to a crop decision-support system: Maintaining satisfactory accuracy while keeping the model simple. European Journal of Agronomy, 151, art. 126999, https://dx.doi.org/10.1016/j.eja.2023.126999, https://hal.inrae.fr/hal-04288580
Godinot O, Carof M, Vertes F, Leterme P, 2014. SyNE: an improved indicator to assess nitrogen efficiency of farming systems. Agric. Syst. 127, 41–52. https://doi.org/10.1016/j.agsy.2014.01.003.
Parnaudeau V., Reau R., Dubrulle P., 2012. Un outil d'évaluation des fuites d'azote vers l'environnement à l'échelle du système de culture : le logiciel Syst'N. Innovations Agronomiques 21, 59-70.
| Keywords | nitrogen, cropping systems, low input trials, efficiency, modeling |
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