Characterizing the spatiotemporal dynamics of soil water stable isotopes on a karst hillslope in southwestern China

2021 ◽  
Author(s):  
Qin Liu ◽  
Tiejun Wang ◽  
Cong-qiang Liu ◽  
Xi Chen
Keyword(s):  
Soil Water ◽  
Temporal Stability ◽  
Spatiotemporal Dynamics ◽  
Spatial Variations ◽  
Spatiotemporal Variability ◽  
Strong Negative Correlation ◽  
Mean Values ◽  
Spatiotemporal Features ◽  
Field Evidence ◽  
Karst Hillslope

<p>Soil water stable isotope compositions (SWSI; i.e., δD and δ<sup>18</sup>O) and soil moisture content (SMC) are widely used to illuminate water exchange processes across the atmosphere-land interface. Thus, the knowledge of spatiotemporal dynamics of these two variables is critical to help our understanding of relevant ecohydrological processes. However, in comparison to the efforts for elucidating the spatiotemporal variability in SMC, much less attention was paid to understand the spatiotemporal variability in SWSI, which also raises the question as to whether SWSI and SMC share similar spatiotemporal features. To this end, the spatiotemporal dynamics of SWSI and SMC were jointly investigated on a karst hillslope with eight sampling campaigns among two years. The method of temporal stability analysis (TSA) was adopted to evaluate the spatiotemporal patterns of SWSI and SMC in this study. Generally, both δD and δ<sup>18</sup>O exhibited considerable temporal and spatial variations; meanwhile, the variations in δD and δ<sup>18</sup>O values were relatively smaller than that of SMC. In addition, in comparison with the spatial pattern of SMC, there were no clear relationships between the standard deviation (SD) and the spatial mean of δD or δ<sup>18</sup>O. However, the SD of line-conditioned excess (lc-excess) and its mean values displayed a strong negative correlation, indicating that the spatial variations in lc-excess increased with soil evaporation. Moreover, SWSI displayed weaker temporal stability than SMC and no clear controlling factors were identified, suggesting that the spatiotemporal dynamics of SWSI might be more complex than that of SMC. This study provided comprehensive field evidence that there existed profound spatiotemporal variability in SWSI and its spatiotemporal features were different from SMC, highlighting that the spatiotemporal variability in SWSI needs to be considered in isotope-based estimations and it should be investigated separately from the spatiotemporal characteristics of SMC in future studies.</p>

scholarly journals Spatiotemporal variability of soil-water characteristic curve model parameters of Lanzhou collapsible loess

2021 ◽  
Author(s):  
Wenju Zhao ◽  
Yuhang Liu ◽  
Jiazhen Hu ◽  
Zongli Li
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Temporal Stability ◽  
Spatiotemporal Variability ◽  
Model Parameters ◽  
Measuring Point ◽  
Collapsible Loess ◽  
Comprehensive Comparison ◽  
The Mean ◽  
Relative Differences

Abstract The spatiotemporal variation of the model parameters of the soil-water characteristic curve (SWCC) reflect the soil water holding capacity and soil pore distribution state. It is an integral part of interdisciplinary disciplines such as soil hydrodynamics and ecohydrology. The authors selected the optimal SWCC model for the Lanzhou collapsible loess, used classical statistics and geostatistics methods studied the spatiotemporal variability of the SWCC model parameters, and used the comprehensive comparison of the mean relative differences (MRD), standard deviations (SDRD) and an index of temporal stability (ITS) determined the representativeness measuring point. The results showed that the SWCC parameters α was medium variability in the 0–30 cm soil layer, n and θs were of low variability, the spatial distribution of the parameters of different soil layers was consistent. Migration direction prediction of θs was very similar in each layer, α, n and θs were all strongly significantly correlated positively. Moreover, the determination coefficient of representative measuring point 16 had the highest prediction accuracy for the measured values of SWCC. The results of this paper can be used as a simple method to predict SWCC and provide theoretical guidance for soil water management and soil collapse erosion monitoring in collapsible loess area. HIGHLIGHT Presented a study of the temporal stability and variability of SWCC in the Lanzhou collapsible loess, using the comprehensive comparison of the Mean relative differences (MRD), standard deviations (SDRD) and an index of temporal stability (ITS), and determined the representativeness measuring point.

Field evidence for a bi-porous soil water regime in clay soils

1986 ◽  
Vol 11 (2) ◽  
pp. 117-125 ◽  
Author(s):  
Adrian C. Armstrong ◽  
Robert Arrowsmith
Keyword(s):  
Soil Water ◽  
Water Regime ◽  
Clay Soils ◽  
Soil Water Regime ◽  
Field Evidence ◽  
Porous Soil

scholarly journals Temporal stability of electrical conductivity in a sandy soil

2016 ◽  
Vol 30 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Aura Pedrera-Parrilla ◽  
Eric C. Brevik ◽  
Juan V. Giráldez ◽  
Karl Vanderlinden
Keyword(s):  
Electrical Conductivity ◽  
Spatial Variability ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Precision Agriculture ◽  
Temporal Stability ◽  
Principal Component ◽  
Model Parameters ◽  
Soil Spatial Variability

Abstract Understanding of soil spatial variability is needed to delimit areas for precision agriculture. Electromagnetic induction sensors which measure the soil apparent electrical conductivity reflect soil spatial variability. The objectives of this work were to see if a temporally stable component could be found in electrical conductivity, and to see if temporal stability information acquired from several electrical conductivity surveys could be used to better interpret the results of concurrent surveys of electrical conductivity and soil water content. The experimental work was performed in a commercial rainfed olive grove of 6.7 ha in the ‘La Manga’ catchment in SW Spain. Several soil surveys provided gravimetric soil water content and electrical conductivity data. Soil electrical conductivity values were used to spatially delimit three areas in the grove, based on the first principal component, which represented the time-stable dominant spatial electrical conductivity pattern and explained 86% of the total electrical conductivity variance. Significant differences in clay, stone and soil water contents were detected between the three areas. Relationships between electrical conductivity and soil water content were modelled with an exponential model. Parameters from the model showed a strong effect of the first principal component on the relationship between soil water content and electrical conductivity. Overall temporal stability of electrical conductivity reflects soil properties and manifests itself in spatial patterns of soil water content.

Use of water extraction variability to screen for sunflower genotypes well adapted to soil water limitation

2012 ◽  
Vol 39 (12) ◽  
pp. 999
Author(s):  
Ando M. Radanielson ◽  
Jeremie Lecoeur ◽  
Angelique Christophe ◽  
Lydie Guilioni
Keyword(s):  
Soil Water ◽  
Phenotypic Variability ◽  
Water Extraction ◽  
Breeding Programs ◽  
Mean Values ◽  
Relative Value ◽  
Water Uptake Capacity ◽  
Extraction Properties ◽  
Soil Water Extraction ◽  
The Mean

In conditions of water deficit, plant yield depends mostly on the ability of the plant to explore soil profile and its water uptake capacity per unit volume of soil. In this study, the value of soil water extraction properties for use in sunflower breeding was evaluated. Five experiments were carried out in pots, in greenhouses, from 2005 to 2009, in Montpellier, France. Elite sunflower cultivars and experimental hybrids obtained from a factorial cross between five female and five male inbred lines were grown. The soil water extraction performance of the plants was characterised by the soil water content at minimal stomatal conductance (SWCgs = 0) and the index of water extraction (IEgen), which was calculated as the relative value of SWCgs = 0 to the performance of the cultivar NKMelody. Heritability (H2) was estimated for the experimental hybrids. Phenotypic variability of the SWCgs = 0 was observed with a significant effect of the environment and the genotype. The latest released cultivars were observed as the best performing one in water extraction with an IEgen under 0.85. This trait was found to be suitable for use in comparisons of the soil water extraction performances of different genotypes. The high H2 value for SWCgs = 0 (0.77 and 0.81) and the significant correlation (r2 = 0.70, P < 0.001) between the values obtained for the experimental hybrids and the mean values of the general combining ability (GCA) for the parental lines showed that this trait is heritable and could be used in plant breeding programs. Phenotyping methods and the usefulness of this trait in crop modelling are discussed.

Solute accumulation and osmotic adjustment in leaves of Brassica oilseeds in response to soil water deficit

2004 ◽  
Vol 55 (9) ◽  
pp. 939 ◽  
Author(s):  
Qifu Ma ◽  
David W. Turner ◽  
David Levy ◽  
Wallace A. Cowling
Keyword(s):  
Soil Water ◽  
Water Deficit ◽  
Osmotic Adjustment ◽  
Soluble Sugars ◽  
Indian Mustard ◽  
Water Soluble ◽  
Soil Water Deficit ◽  
Mean Values ◽  
Solute Accumulation ◽  
Dh Lines

To establish methods for improving drought tolerance in Brassica oilseeds, we examined the influence of soil water deficit on solute accumulation in expanded and expanding leaves. We assessed the contribution of individual solutes to osmotic adjustment (OA) and determined the effect of homozygosity on the variation of the expression of OA. Juvenile plants of canola (Brassica napus cvv. Karoo and Monty) and Indian mustard (B. juncea line PI-81792) were grown under glasshouse conditions. The 3 genotypes expressed similar magnitudes of OA in response to drought, compared with a 2-fold higher OA in expanding leaves than in fully expanded leaves. Drought-induced changes in OA of expanded leaves of all genotypes were largely due to the accumulation of nitrate (42−47%), soluble sugars (31−38%), and proline (11−14%). In expanding leaves, K+ accumulation was significant (23–27%) as was proline (17−22%), whereas nitrate and soluble sugars were less important than in expanded leaves. By comparison, ions of Na+, Cl–, and water-soluble Mg2+ and Ca2+ did not contribute significantly to OA. Proline was hardly detected in well watered plants, but sharply increased in leaves of droughted plants in direct proportion to the magnitude of OA (80 ± 7 mmol/MPa, r2 = 0.94). A comparison between doubled haploid (DH) and commercial seed sources of 2 B. napus cultivars showed similar mean values in OA. The DH lines had a 33% lower coefficient of variation in OA than cv. Karoo and 48% lower than cv. Monty among replicate plants. Proline may be a suitable ‘marker’ for OA in juvenile Brassica plants because of all the solutes measured, its concentration was directly proportional to the magnitude of OA across cultivars and leaf types. The use of DH lines will improve the precision in selection of genotypes that have the capacity to osmotically adjust under soil water deficit.

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