Field capacity (FC) is crucial for modelling soil–plant–water dynamics with bucket-type models, supporting prevention of environmental problems (e.g. chemical leaching to deeper layers and groundwater and waste of water resources). As FC measurement in situ is labour intensive, approaches for its estimation have been proposed. However, because they differ conceptually and are based on different assumptions, the response to an application (e.g. crop yield (CY) modelling) can be rather different. This study evaluated frequently used FC approaches in scenarios quantifying differences in behaviour of soil water and air retention, evapotranspiration (ET) and CY. Also, a soil texture-based pedotransfer function (PTF) was compared with other methods. Six sites with different soil types and management practices from tropical and temperate climates were investigated. Field capacity was estimated based on a static criterion using the water content (θ) at pressure heads (h) of 0.6, 1 and 3.3 m and at the inflection point (θ i ) of all water retention curves (SWRCs) and the Assouline and Or model (AO). Moreover, four equations found in the literature based on a dynamic criterion were also evaluated. For all soils, the largest FC results were obtained when θ i was set as FC. The smallest FC values were obtained with θ (3.3 m) (tropical) and AO (temperate). The coefficient of variation (CV) between FC estimates, based on nine approaches, ranged from 7 to 54%. Available water storage, air capacity (AC) and ET results were sensitive to FC and showed more variation for the Brazilian sites. The PTF used estimated FC within the range of results obtained by the other nine approaches. In addition, AquaCrop was used to study the effect of FC on CY by fixing all model parameters, whereas FC was the only flexible parameter. Crop yield was sensitive to the variation in FC under low and medium rainfall, but increased with larger FC. For high rainfall, the yield was small in a scenario with large θ fc because AC became yield limiting. Highlights: Different approaches can be used to estimate field capacity The criteria static and dynamic and a texture-based PTF were evaluated Sensitivity analyses were performed with parameters of bucket type model and crop yield simulations Results showed that management decisions differed according to field capacity criteria.
|Number of pages||13|
|Journal||European Journal of Soil Science|
|State||Published - Mar 2019|
Bibliographical noteFunding Information:
This is paper No 18-06-080 of the Kentucky Agricultural Experiment Station and published with the approval of the Director. The third author (O.W.) acknowledges support by the USDA National Institute of Food and Agriculture, Multistate Project KY006093 and the SB271 Water Quality Program at the College of Agriculture, Food and Environment, University of Kentucky.
© 2018 British Society of Soil Science
Copyright 2019 Elsevier B.V., All rights reserved.
ASJC Scopus subject areas
- Soil Science