Six crop models differ in their simulation of water uptake

G. G. Camargo and A. R. Kemanian

Agricultural and Forest Meteorology (15 April 2016)

DOI: 10.1016/j.agrformet.2016.01.013

Abstract Root water uptake is an essential component of crop models since it affects plant growth and, through its effect on the soil water balance, multiple soil and nutrient cycling processes. Several methods to simulate water uptake exist; however, the differences among them have not been evaluated. We compared the water uptake methods implemented in six crop models: APSIM, CropSyst, DSSAT, EPIC, SWAP and WOFOST. These methods range from simple empiric approaches (WOFOST) to mechanistic approaches based on the water potential gradient and root distribution in the soil–plant system (CropSyst). We compared the six models’ water uptake algorithms in scenarios with different evaporative demand, soil texture, and water distribution with depth. The main difference among methods derived from the degree to which each model enabled the use of water in the subsoil (below 0.5 m). In a rooted, 1-m deep silt loam soil in which the root density decreased geometrically with depth and which was subjected to an evaporative demand of 5 mm d−1 for 60 days, APSIM, EPIC, DSSAT and SWAP transpired about 83

keywords: Crop model comparison; Water uptake; Water stress; Root distribution

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