Multi‐model simulation and evaluation of soil moisture characteristic curves in artificial apricot orchards based on one‐dimensional horizontal infiltration method

Abstract

The soil water characteristic curve (SWCC) can quantitatively characterize and predict the retention, movement, and exploitability of soil water in drylands. It holds key scientific significance for optimizing water management, guiding agricultural production, and promoting ecological restoration. In the present research, soil specimens were collected from apricot ( Prunus armeniaca L.) groves in the hilly regions of southern Ningxia to examine how varying ages of apricot trees influence the SWCC. The accuracy and variability of SWCC measurements in apricot orchards of different ages were assessed using the one‐dimensional horizontal infiltration method. Additionally, unsaturated hydraulic conductivity ( K _θ ), unsaturated diffusion coefficient ( D ), and related hydrological parameters were estimated. The feasibility and accuracy of the one‐dimensional horizontal infiltration method were evaluated using the in situ continuous evaporation method with a tensiometer. The results indicated that, compared with CK (farmland corn field), it took 78.89% longer for the wetting front to reach a depth of 40.0 cm in the 35‐year‐old stand, and sorptivity ( S ) decreased by 36.36%. A comparative analysis of the low matric potential range SWCC, obtained using both the one‐dimensional horizontal infiltration technique and the tensiometer technique, revealed that the R ² value was greater than 0.765, while the root mean square error (RMSE) and mean absolute error (MAE) were both less than 0.1 cm ³ /cm ³ . This demonstrates that the one‐dimensional horizontal infiltration method has high precision in measuring the SWCC of forest soil. A comparison of the estimation results from two SWCC models, namely, the van Genuchten model as well as the Brooks–Corey model, showed that the van Genuchten model had a higher R ² value and lower RMSE and MAE compared to the Brooks–Corey model. This indicates that the van Genuchten model is more effective at predicting the SWCC of forest soil. Under the same moisture content conditions, both the K _θ and the D diminished as stand age increased. The study concluded that hydraulic permeability progressively waned with the escalation of forest age. It also substantiated that the one‐dimensional horizontal infiltration technique is an expeditious and dependable means for gauging the SWCC and pivotal hydrodynamic parameters of forest soil in arid zones.