Stimulated and Measured Soil Water Dynamics of Unfertilized and Fertilzed Barley

Abstract

A physical-based numerical model was used to analyse soil water dynamics in stands of unfertilized and fertilized barley. The model, which was run on standard meteorological data as input, was adapted to a field site in Central Sweden (Lat. 60°10'N, 17°38'E). Parameter values, describing both soil and plant properties, were adjusted to obtain agreement with measurements. Soil cores were used for determination of the water retention curve and hydraulic conductivity was estimated with a method accounting for the contribution of both the macropores and of the capillary pores. Field measurements with tensiometers and with a neutron probe showed a tendency for drier conditions to occur in fertilized stands than in unfertilized stands. This was explained by systematic differences in soil properties within the field and by a difference in evaporative demand resulting from the fertilization of barley. The agreement obtained between model predictions and measurements was generally good. However, it is stressed that it would be better if especially more of the plant properties could be estimated with independent methods. This would enable the model to be used for predictions even when no or only few soil water measurements are available. Such predictions of the water balance and of soil water conditions would be useful when nutrient dynamics or crop yield are to be analysed for different agricultural ecosystems.