K. Blomback et al., SIMULATION OF WATER AND NITROGEN FLOWS AND PLANT-GROWTH FOR A WINTER-WHEAT STAND IN CENTRAL GERMANY, Ecological modelling, 81(1-3), 1995, pp. 157-167
Two linked simulation models were applied to an experimental loam site
at Neuenkirchen, Germany, for the years 1989 and 1991, using a data s
et with soil and plant properties for winter wheat. Simulations of soi
l water and heat dynamics were performed with the SOIL model. Both yea
rs were rather dry. For the first year, soil water content and soil wa
ter tension were calibrated by tuning the saturated hydraulic conducti
vity. The simulations showed good correspondence with the measurements
during the first six months down to 130 cm depth. However, the dynami
cs of the simulated water tension in deeper layers was poor compared t
o the measurements. Using the same parameterization for 1998, the mode
l simulated soil moisture dynamics reasonably well in the upper 70 cm.
Below this depth, the water content was underestimated. Soil and plan
t nitrogen dynamics, litter decomposition and plant biomass production
were simulated with the SOILN model. The model was tested against mea
surements of leaf, stem and grain biomass and nitrogen, leaf area and
soil nitrate and ammonium content. It was calibrated for the first yea
r (1989) and validated in 1991. Parameters related to translocation of
assimilates and nitrogen from different tissues to grain were estimat
ed by calibration. The simulated plant properties in 1989 explained ab
out 95% of the variations in measured values. A similar agreement was
obtained for the validation year. The corresponding value for soil min
eral nitrate in 1989 was only 38%, mainly due to problems in reproduci
ng the dynamics in the upper 30 cm in connection to fertilization appl
ications. In deeper layers up to 90% of the variation was explained. F
or nitrate in 1991 and ammonium the agreement between simulated and me
asured values was poor.