How Much Complexity Is Required for Modelling Grassland Production at Regional Scales?

Studies evaluating the complexity of models, which are suitable to simulate grass growth at regional scales in intensive grassland production systems scarce. Therefore, two different models (GrasProg1.0 and APSIM) with input requirements were compared against long-term observations from variety trials perennial ryegrass (Lolium perenne) Germany Denmark. The trial sites covered a large range environmental conditions, annual average temperatures ranging 5.9 10.3 °C, rainfall 536 1154 mm. also varied regarding soil type, for modelling categorised into three groups according their plant available water (PAW) content: light soils PAW 60 mm, medium 80 heavy 100 objective was investigate whether simple model performed equally well given low number inputs, namely climate group. Evaluation statistics showed that both provided satisfactory results, root mean square errors individual cuts 0.59 1.28 t dry matter ha−1. efficiency (Nash–Sutcliffe efficiency) separate good 81% having positive Nash–Sutcliffe value GrasProg1.0, 72% APSIM. These results reveal without detailed site-specific descriptions, less complex GrasProg1.0 can be incorporated decision support tool optimising management livestock systems.