Performance assessment of the FAO AquaCrop model for soil water, soil evaporation, biomass and yield of soybeans in North China Plain

Abstract

Four years of soybean experimental data observed at Daxing, North China Plain, were used to assess the ability of the AquaCrop model to predict soybean final biomass and yield. The model was parameterized and calibrated using field data on leaf area index (LAI), available soil water, soil evaporation, biomass and final yield data. The model was assessed using calibrated and default parameters. Data on LAI was used to derive the fraction of ground cover and to calibrate the green canopy cover (CC) curve. An accurate calibration of the CC curve was performed, with low root mean square errors (RMSE < 7.3%). Results relative to soil water balance simulations show a high variability of the predictions, thus a bias of the estimation, with R 2 ranging 0.22-0.86 and low Nash-Sutcliffe efficiency EF, ranging between-0.47 and 0.82. The estimation errors were relatively high, with RMSE not exceeding 22.9 mm. AquaCrop was compared with the soil water balance model SIMDualKc, that has shown better performance with R 2 ≥ 0.83, EF generally greater than 0.75 and RMSE smaller than 12.5 mm. The soil evaporation (E s) simulations were compared with the observations performed using microlysimeters; results for Aquacrop have shown a clear trend for underestimation of E s , with "goodness-of-fit" results worse than for SIMDualKc (Wei et al., 2015). In general, AquaCrop has shown serious limitations to estimate crop transpiration or soil *Revised Manuscript with No changes Marked Click here to view linked References

Water Use and Yield of Soybean under Various Irrigation Regimes and Severe Water Stress. Application of AquaCrop and SIMDualKc Models

“…The value for K cTr,x = 1.10 equals the K cb mid calibrated with SIMDualKc (Table 2). Similar values were reported by Abi Saab et al [15] and Paredes et al [16]. BWP* = 14 g·m −2 equals the one reported by Abi Saab et al [15] and Khoshravesh et al [55]; a higher value was reported by Paredes et al [16].…”

“…Therefore, K e tends to be higher with AquaCrop when water deficits occur. Under no stress conditions, differences are negligible (Figure 2c,d) as observed by Paredes et al [16].…”

“…For no-stress conditions, HIo observed in both seasons averaged 0.38. That HIo value equals that reported by Paredes et al [16]; slightly smaller values were reported by Andrade [2] and larger values by Abi Saab et al [15] and Khoshravesh et al [55]. Differences in BWP* and HIo values may relate to soybean varieties.…”

“…Nevertheless, results in the current study relative to AquaCrop applications are in the range of those reported by Mercau et al [7] using CROPGRO-Soybean and Cera et al [12] using SoySim. However, better results using AquaCrop for soybean were reported by Abi Saab et al [15], Paredes et al [16], and Battisti et al [27] whose studies only considered small water stress levels. The above referred results are likely due to the previously discussed poor estimation of actual transpiration when water stress occurs.…”

“…These values are within the range of other AquaCrop applications to soybean [15,16,55]; thus, one may consider the parameterization of the CC curves in the current study adequate. and (e,f) rain-fed in 2012-2013 (error bars indicate the standard deviation of SWC observations; θSat, θFC, θWP, and θp are, respectively, the SWC at saturation, field capacity, wilting point, and at the threshold depletion for no stress).…”