Calibration and validation of the SWB irrigation scheduling model for soybean [Glycine max. (L.) Merr., indeterminate cv. Wayne]

Abstract

Soil Water Balance (SWB) is a mechanistic, irrigation scheduling, generic crop model including a database of crop specific growth parameters. The objective of this study was to calibrate and validate this model for soybean [Glycine max. (L.) Merr., indeterminate cv. Wayne], Detailed weather, soil and crop data were made available from a field trial carried out at Western Iowa Experimental Farm, Castana, Iowa, USA, where soybean was grown under irrigated and rainfed conditions. Crop specific growth parameters were determined for soybean grown in 0.25 m and 1.0 m wide rows. Weather, soil, crop and irrigation measurements were then used in SWB to calibrate and validate the crop growth and soil water balance subroutines of the model. Simulations were inside, or marginally outside the reliability criteria imposed, both in the case of the irrigated and rainfed treatments. This gives confidence that the user-friendly, generic crop model can be used to accurately schedule irrigations of soybean.