Simulation of the effect of water shortage on the yields of winter wheat in North-East England

The soil–plant–atmosphere system is modelled quantitatively, treating soil water as a limiting factor. A single-reservoir soil–water model was developed and linked to the solar driven computational model of crop growth, known as ‘SODCOM’. The soil–water model is validated by comparing the predictions of the model with field measurements on different soils. The soil–water model uses a daily timestep and is based on potential evapotranspiration and soil–water retention parameters. These parameters were linked to a root zone water balance of rainfall, runoff and evapotranspiration. The model estimates a water growth factor, which is used to modify the potential rate of growth. Plant growth was estimated by SODCOM which simulates photosynthesis, respiration and partitioning of assimilates for vegetative and reproductive growth. In addition to calculating growth rate, the combined models demonstrate a strategy which a wheat crop (Triticum aestivum L.) may use to combat drought. There is good agreement between the simulated and measured values of soil moisture throughout two growing seasons, statistical analysis obtained a concordance correlation of 0.87. Grain yields in North-East England were predicted within 0.4 Mg/ha (5.5%), including situations where moisture stress was the result of poor soil texture and water retention, and also where soil conditions restrict the rooting depth of the crop.