The Role of Hydraulic Connectivity and Management on Soil Aggregate Size and Stability in the Clear Creek Watershed, Iowa

The role of tillage practices on soil aggregate properties has been mainly addressed at the pedon scale (i.e., soilscape scale) by treating landscape elements as disconnected. However, there is observed heterogeneity in aggregate properties along flowpaths, suggesting that landscape scale hydraulic processes are also important. This study examines this supposition using field, laboratory and modeling analysis to assess aggregate size and stability along flowpaths under different management conditions: (1) tillage-induced abrasion effects on aggregate size were evaluated with the dry mean weight diameter (DMWD); (2) raindrop impact effects were evaluated with small macroaggregate stability (SMAGGSTAB) using rainfall simulators; and (3) these aggregate proxies were studied in the context of connectivity through the excess bed shear stress (δ), quantified using a physically-based landscape model. DMWD and SMAGGSTAB decreased along the flowpaths for all managements, and a negative correspondence between the proxies and δ was observed. δ captured roughness effects on connectivity along the flowpaths: highest connectivity was noted for parallel-ridge-till flowpaths, where δ ranged from 0–8.2 Pa, and lowest connectivity for contour-ridge-till flowpaths, where δ ranged from 0–1.1 Pa. High tillage intensity likely led to an increase in aggregate susceptibility to hydraulic forcing, reflected in the higher gradients of aggregate size and stability trendlines with respect to δ. Finally, a linear relationship between DMWD and SMAGGSTAB was established.

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Stabilization of Soil Aggregates in Relation to Soil Redistribution by Intensive Tillage on a Steep Hillslope

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.955-959.3566 ◽

2014 ◽

Vol 955-959 ◽

pp. 3566-3571 ◽

Cited By ~ 1

Author(s):

Yong Wang ◽

Zhuang Xiong ◽

Wu Xian Yan ◽

Yue Qun Qiu

Keyword(s):

Soil Aggregates ◽

Geometric Mean ◽

Aggregate Stability ◽

Aggregate Size ◽

Soil Aggregate ◽

Soil Aggregate Stability ◽

Mean Weight Diameter ◽

Tillage Operation ◽

Sloping Land ◽

The Impact

The objective of this study was to investigate soil aggregate stability within landscape on hillslopes by intensive tillage. Traditional tillage by consecutive hoeing was performed 5 and 20 times on steeply sloping land of the Sichuan Basin, China, by using the methods of simulated tillage to analyze the impact of long-term tillage on soil aggregates at different slope positions. The dry-sieved method was used to determine distribution of aggregate size in the different landscape positions, and mean weight diameter (MWD) and geometric mean diameter (GMD) as indices of soil aggregate stability. The different times of tillage resulted in different soil aggregate distributions. The results showed that the MWD and GMD values of aggregates were significantly decreased (p< 0.05) after 20-tillage operation, compared with pre-tillage operation. The differences in distributions of MWD and GMD demonstrate that the choice of the tillage times can be an important factor in changing soil aggregate stability and productivity in steeply sloping fields.

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Lime application effects on soil aggregate properties: Use of the mean weight diameter and synchrotron-based X-ray μCT techniques

Geoderma ◽

10.1016/j.geoderma.2018.10.035 ◽

2019 ◽

Vol 338 ◽

pp. 585-596 ◽

Cited By ~ 10

Author(s):

Talita R. Ferreira ◽

Luiz F. Pires ◽

Dorthe Wildenschild ◽

André M. Brinatti ◽

Jaqueline A.R. Borges ◽

...

Keyword(s):

Soil Aggregate ◽

X Ray ◽

Aggregate Properties ◽

Mean Weight Diameter ◽

The Mean ◽

Lime Application

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Soil Aggregate-Associated Carbon Fraction Dynamics during the Process of Tea (Camellia sinensis L.) Planting in Southern Guangxi, China

Forests ◽

10.3390/f12111530 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1530

Author(s):

Chao Zhang ◽

Xinxin He ◽

Shaoming Ye ◽

Shengqiang Wang

Keyword(s):

Soil Aggregates ◽

Aggregate Size ◽

Soil Aggregate ◽

Vital Role ◽

Soil Layers ◽

Mean Weight Diameter ◽

Recalcitrant Carbon ◽

Tea Plantations ◽

The Mean ◽

The Stability

Revealing the variation in soil aggregate-associated organic carbon (Corg) in tea plantations of various planting ages is crucial to shed more light on the accumulation and decomposition of soil Corg in the tea-planting period. This study measured the concentrations of soil Corg, active carbon (Cact), and recalcitrant carbon (Crec) in different-sized aggregates obtained from tea plantations of various planting ages (8, 17, 25, and 43 years old) at the soil depths of 0–20 and 20–40 cm in southern Guangxi, China. According to the wet-sieving approach, soil aggregates were classified as macro- (>0.25 mm) and micro- (<0.25 mm) aggregates, and the former were further divided into coarse (>2 mm), medium (2–1 mm), and fine (1–0.25 mm) fractions. Based on the mean weight diameter (MWD), the stability of soil aggregates was the highest in the 17-year-old tea plantations, and it was closely related to the concentration of soil Cact (0–20 cm: R2 = 0.9744, p < 0.05; 20–40 cm: R2 = 0.8951, p < 0.05), but not Corg (0–20 cm: R2 = 0.1532, p > 0.05; 20–40 cm: R2 = 0.4538, p > 0.05), during the tea-planting process. In the 0–20 and 20–40 cm soil layers, the coarse and medium macro-aggregates had higher concentrations of Corg, Cact, and Crec, regardless of the tea-planting age; meanwhile, the soil Cact/Crec ratio, indicating the Corg availability, increased as aggregate size increased, implying that the soil Corg was younger and more labile in coarse macro-aggregates relative to finer aggregates. Moreover, the tea-planting age significantly affected the Corg, Cact, and Crec reserves in both soil layers. To be specific, continuous tea planting facilitated the accumulation of soil Corg and Crec, but their reserves’ increase rates decreased over time; meanwhile, the soil Cact reserve increased during the early (from 8 to 17 years) tea-planting stage and later decreased. Therefore, during the middle (from 17 to 25 years) and late (from 25 to 43 years) tea-planting stages, maintaining the soil as an Cact pool plays a vital role in facilitating the formation and stabilization of soil aggregates in southern Guangxi, China.

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Comments on “Fractal Dimensions of Soil Aggregate-Size Distributions Calculated by Number and Mass”

Soil Science Society of America Journal ◽

10.2136/sssaj1993.03615995005700050038x ◽

1993 ◽

Vol 57 (5) ◽

pp. 1393-1393 ◽

Cited By ~ 11

Author(s):

Alex B. McBratney

Keyword(s):

Aggregate Size ◽

Fractal Dimensions ◽

Soil Aggregate ◽

Size Distributions

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Soil aggregate size-dependent relationships between microbial functional diversity and multifunctionality

Soil Biology and Biochemistry ◽

10.1016/j.soilbio.2021.108143 ◽

2021 ◽

Vol 154 ◽

pp. 108143

Author(s):

Shun Han ◽

Manuel Delgado-Baquerizo ◽

Xuesong Luo ◽

Yurong Liu ◽

Joy D. Van Nostrand ◽

...

Keyword(s):

Functional Diversity ◽

Aggregate Size ◽

Soil Aggregate ◽

Microbial Functional Diversity ◽

Size Dependent

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Individual differences and emotional labor: the effects of core self-evaluations on depersonalization

Journal of Management & Organization ◽

10.1017/jmo.2021.2 ◽

2021 ◽

pp. 1-20

Author(s):

Lucas Pujol-Cols ◽

Guillermo E. Dabos ◽

Mariana Lazzaro-Salazar

Keyword(s):

Emotional Labor ◽

Structural Equation ◽

Vital Role ◽

Equation Modeling ◽

Emotional Dissonance ◽

Modeling Analysis ◽

Emotional Aspects ◽

Emotional Demands ◽

Core Self

Abstract This paper examines the role of core self-evaluations (CSEs) in the relationships among emotional demands, emotional dissonance, and depersonalization. Data were collected from a non-random sample of 423 teachers who worked in primary, secondary, and higher education institutions. Results from structural equation modeling analysis showed that CSEs displayed both direct and indirect effects on depersonalization through employees' perceptions and reactions to emotional labor. Specifically, those individuals with more positive CSEs tended to perceive the emotional aspects of their job as less demanding, thus being less likely to experience emotional dissonance and, in turn, depersonalization. This research demonstrated that CSEs play a vital role in explaining employees' reactions to emotional labor and, therefore, their effects should be properly accounted for in future studies. Implications for practice and future lines of research are discussed in this paper.

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