Pedosphere 34(3): 590--605, 2024
ISSN 1002-0160/CN 32-1315/P
©2024 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Plant-available water capacity of soils at a regional scale: Analysis of fixed and dynamic field capacities |
Vinod PHOGAT1,2,3 , Paul R. PETRIE1,2,3,4, Casandra COLLINS2,5, Marcos BONADA1,3 |
1 South Australian Research and Development Institute, GPO Box 397, Adelaide SA 5001 (Australia)
2 School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Waite Campus, PMB1, Glen Osmond SA 5064 (Australia)
3 College of Science and Engineering, Flinders University, Bedford Park SA 5042 (Australia)
4 The University of New South Wales, Sydney NSW 2052 (Australia)
5 ARC Training Centre for Innovative Wine Production, University of Adelaide, PMB1, Glen Osmond SA 5064 (Australia) |
| Corresponding Author:Vinod PHOGAT |
| ABSTRACT |
| Estimation of the plant-available water capacity (PAWC) of soils at a regional scale helps in adopting better land use planning, developing suitable irrigation schedules for crops, and optimizing the use of scarce water resources. In the current study, 72 soil profiles were sampled from the Barossa region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil properties. These functions were then used to estimate the fixed (10 and 33 kPa) and dynamic pressure head (hfc) water contents at field capacity (FC) for minimum drainage flux (0.01 and 0.001 cm d-1), which serves as the upper boundary for plant-available water in soils. The estimated residual water content was corrected for subsoil constraints, especially the exchangeable sodium percentage (ESP). The results showed that the mean values of hfc in sand-dominated light and medium textured soils (i.e., sand, loamy sand, sandy loam, and loam) varied in a narrow range (15.8–18.2 kPa), whereas those in the clay-dominated heavy textured soils (i.e., clay loam) showed a wide range (11.3–49.3 kPa). There were large differences in PAWC for dynamic FC (PAWCfc) and fixed FC at 10 kPa (PAWC10), 33 kPa (PAWC33), and a mix of 10 and 33 kPa (PAWC10,33) pressure heads depending on soil texture. Normally, the difference between PAWC at 10 kPa and hfc (∆PAWC10) was positive, whereas that between 33 kPa and hfc (∆PAWC33) was negative across all sites. Nevertheless, the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures (i.e., PAWC10,33) for sandy, clay, and silty soils reduced the difference between fixed and dynamic pressure PAWCs to < 10% across the region. The estimation of PAWC was improved by incorporating the impact of subsoil constraints, such as high ESP, which was more pronounced for clay and silty soils. These findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic FC estimations in soils. Soil heterogeneity, intra-texture variability, subsoil constraints, and swell-shrink clays can have great impacts on the water retention capacity in response to dynamic and fixed pressure FC values. |
| Key Words: crop lower limit,drained upper limit,pedo-transfer function,soil hydraulic parameter,soil texture |
| Citation: Phogat V, Petrie P R, Collins C, Bonada M. 2024. Plant-available water capacity of soils at a regional scale: Analysis of fixed and dynamic field capacities. Pedosphere. 34(3): 590–605. |
| |
|
View Full Text
|
|
|
|
