Yields and Nitrogen Dynamics in Ley-Arable Systems—Comparing Different Approaches in the APSIM Model

Nitrogen (N) dynamics in ley-arable cropping systems require better understanding order to assess the potential of such contribute improved productivity and reduced nutrient losses crop production. Large inputs organic matter after termination ley phase result increased mineralization N availability subsequent crops. The description quantification this residual effect remains a major scientific challenge due its variability many influencing factors. Simulation modeling could systems. aim study was evaluate robustness Agricultural Production Systems Simulator (APSIM) predict biomass yield, leaching different forage maize northwest Europe, while using two approaches effect. evaluation based on three field experiments covering plant phenology, biomass, over several years. Model adjustments were necessary describe release ploughing grass leys. For purpose, scenarios investigated by accounting for either (1) aboveground residues; (2) above- belowground residues, both with generic turnover approach model; or (3) depending carbon-to-N ratio residue compiled simple model (SMM). results showed that APSIM-simulated yield reasonable poor across sites, regardless residue-related approach. SMM performed more accurately compared predicting following grass-clover ley. However, all scenarios, APSIM had difficulties delay observed experimental data pure ryegrass In conclusion, process related under European pedo-climatic conditions needs is added value improve patterns phase.