Modelling production and environmental impacts of perennial cropping systems with the STICS model

Abstract

The Seventh Environment Action Program of the European commission commits the European Union to "increase efforts to reduce soil erosion and increase organic matter". Use of perennial crops in crop rotation could be a way to meet this objective.Perennial crops differed from annual crops due to their ability to recycle C and N from one year to another. They could also increase C and N storage in soils due to perennial organs death and root system turn-over. We recently improved the STICS model to allow long term simulation of perennial cropping systems, matching with its objective of genericity for crops (Brisson et al., 1998; 2003). We added to the model new formalisms allowing the simulation of C and N fluxes between perennial and non-perennial organs (Strullu et al., 2014) and the simulation of root system turn-over by distinguishing fine and coarse roots (Strullu et al., 2015).The model was able to simulate with accuracy biomass production and N content of different perennial crops in various climate and soil conditions. Moreover, taking into account C and N inputs to the soil due to crop residues allowed a realistic simulation of the evolution of soil organic carbon and nitrogen (SOC and SON respectively).We realized a sensitivity analysis of the evolution of SOC, SON and mineral N in the soil to C and N inputs due to crop residues quantity and quality. Results highlighted the primary role of roots and perennial organs turn-over on C and N storage in soil.Improvements brought to the model allow the simulation on the long term of perennial cropping systems biomass production and environmental impacts. These modifications will also be useful to simulate alternative cropping systems.