Three Bayesian Tracer Models: Which Is Better for Determining Sources of Root Water Uptake Based on Stable Isotopes under Various Soil Water Conditions?

Stable hydrogen and oxygen isotopes provide a powerful technique for quantifying the proportion of root water uptake (RWU) from different potential sources. Although many models coupled with stable have been developed to estimate plant source apportionment, inter-comparisons methods are still limited, especially their performance under soil content (SWC) conditions. In this study, three Bayesian tracer mixing models, which included MixSIAR, MixSIR SIAR, were tested evaluate performances in determining RWU winter wheat various SWC conditions (normal, dry wet) North China Plain (NCP). The proportions layers showed significant differences (p < 0.05) among example, 0–20 cm layer calculated by MixSIR, MixSIAR SIAR was 69.7%, 50.1% 48.3% third sampling condition 0.05), respectively. Furthermore, average lower than that normal wet conditions, being 45.7%, 58.3% 59.5%, No difference > found main depth (i.e., cm) except individual periods. allocation varied conditions: indicators such as coefficient determination (R2) Nash-Sutcliffe efficiency (NS) higher showing performed well rank then SIAR. Overall, relatively better other predicting moisture