Criteria for the estimation of field capacity and their implications for the bucket type model

Abstract

Summary 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 (θi) 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 θi 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 θfc 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

Detection of physical hazards in soil profiles using quantitative soil physical quality assessment in the Pannonian basin, Eastern Austria

“…arbitrarily. A high degree of variability between results from different methods was found (Turek et al, 2019) and this supposedly has an influence over the outcomes of SPQ assessments. Further research concerning the consequences of method choice is required to facilitate study design and the interpretation of results.…”

“…Of the eight SPQIs used, four are directly linked to field capacity (FC) despite the ongoing discussion which has already led to a range of different determination approaches (e.g. Assouline and Or, 2014;de Jong van Lier, 2017;Turek et al, 2019). Most methods were developed based on extensive databases and with a comprehensible theoretical background, hence they imply comparable reliability and the decision to use a certain method is usually made Fig.…”

“…A continuous non-linear function (van Genuchten, 1980) was fitted to the resulting data pairs as a basis for the calculation of the corresponding SPQ-indicators. In particular, field capacity (FC) is a determinant for several SPQIs related to the WRC, but the underlying concept and the measurement methods are not clearly defined (Assouline and Or, 2014;Turek et al, 2019). Hence, we used a dynamic approach to calculate FC which was found to yield plausible results for a wide range of soil types (Twarakavi et al, 2009;Turek et al, 2019).…”

In situ Field Capacity in Brazilian Soils and a Derived Irrigation Management Practice Based on Water Suction

“…For example , Ottoni Filho et al (2016) demonstrated that none of these three suction values in isolation represented in situ FC in their database adequately. Turek et al (2018) analyzed various approaches of indirect determination of FC based on hydrodynamic and hydrostatic criteria, also adopting the suction values of 60, 100 and 330 cm. Their results showed that the FC values in general varied significantly depending on the determination criterion used.…”

Performance of the Groenevelt and Grant Model for Fitting Soil Water Retention Data from Brazilian Soils

“…The SWRC is used in soil physics as well as in related areas like hydrology, soil conservation, irrigation and drainage, among others. The SWRC directly links to the soil pore size distribution function, and is used in hydrological studies (Silva et al, 2017), soil physical quality evaluation (Reynolds et al, 2009;Armindo and Wendroth, 2016) as well as in the prediction of field capacity (Turek et al, 2018) and crop water availability (Feddes and Raats, 2004). The understanding of soil water dynamics is important in applications involving infiltration, water redistribution, evaporation, and root water uptake, and helps to promote management that allows an increase in water use efficiency (Prevedello and Armindo, 2015).…”