High contents of structural carbohydrates in forage maize may limit digestibility and fodder intake of ruminants, and reduce methane output in biogas plants. The concentration of water soluble carbohydrates (WSC) is a main determinant of the ensiling potential of forages and the aerobic stability of silages. However, only few comparative studies of the impact of different hybrids and environments on contents of WSC and cell wall constituents are available. A three-year field experiment was conducted in northern Germany to evaluate differences in contents of whole-crop and stover fibre (neutral detergent fibre, acid detergent fibre, cellulose, hemicellulose, acid detergent lignin) and WSC among a set of commercial hybrids covering three maturity groups (early to mid-late) and different maturation types (dry-down, normal, stay-green). At six dates throughout the vegetation period the plants were harvested, separated into ear and stover, and freeze-dried for subsequent forage quality analysis. The field trial additionally provided a calibration database for the dynamic FOPROQ and FONSCH models to quantify relative contributions of individual environmental factors (temperature, radiation, soil water availability) on fibre and WSC contents. Analysis of the field data revealed a significant influence of genotype and environment on stover and whole crop contents of WSC and fibre components, yet genotypic effects were most pronounced in the early grain filling period. Model calibrations showed good agreement between observed and calculated values, with parameter estimates indicating a substantial influence of temperature and solar radiation on carbohydrate fractions, while the impact of soil water availability was negligible. Successful model calibration allowed to perform a 30-year simulation study, where variation among years was substantial for WSC and moderate for fibre contents, while the impact of genotype on all quality parameters was less pronounced.