Estimation of aggregate stability indices in Mediterranean ...

The proportion of water stable aggregates larger than 0.25 mm (WSA), mean weighted aggregate diameter (MWD) and water dispersible clay (WDC) are three good indicators of the risk of surface sealing, runoff generation and soil erosion by water. These aggregation indices are influenced by the contents in clay, iron oxides, calcium carbonate and organic matter, among other soil properties.

5.10.4. CALCULATIONS FOR THE MARSHALL MIX DESIGN OF ...

Aggregate: Measure the Bulk (Dry) Specific Gravity of the coarse and fine aggregate fractions (KT-6, Procedure I & II). 2.1.2. Reclaimed Material: KT-6, as indicated above can be used on extracted aggregate if a sufficient quantity is available. If sufficient extracted aggregate is not available, conduct KT-39 on the reclaimed material.

Soil Quality Information Sheet Soil Quality Indicators ...

Aggregate stability refers to the ability of soil aggregates to resist disruption when outside forces (usually associ-ated with water) are applied. Aggregate stability is not the same as dry aggregate stability, which is used for wind erosion prediction. The latter term is a size evaluation.

Dry Soil-Aggregate Stability: Energy-Based Index'

Dry Soil-Aggregate Stability: Energy-Based Index' E. L. SKIDMORE AND D. H. POWERS' ABSTRACT Most methods used to estimate aggregate stability apply an un- measured force, or a measured force without knowledge of transfer, to a single or a group of aggregates. A technique is needed to estimate

The effects of wetting rate on aggregate stability in ...

The effects of wetting rate on aggregate stability in three soils Fan Yuntao1 – Liu Jigen2 – Cai Qiangguo1,3 1 College of Water Conservancy and Civil Engineering, China Agricultural University, 100083 Beijing, China 2 Yangtze River Scientific Research Institute, 430010 Wuhan, China 3 Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences …

An evaluation on using soil aggregate stability as the ...

Abstract. Aggregate stability is a very important predictor of soil structure and strength, which influences soil erodibility. Several aggregate stability indices were selected for estimating interrill erodibility of four soil types with contrasting properties from temperate and subtropical regions of China.

Estimation of aggregate stability indices in Mediterranean ...

Aug 15, 2010· Aggregate stability is a good indicator of the susceptibility of soil to surface sealing and wind, rain and runoff erosion (Nimmo and Perkins, 2002). These are key processes in Mediterranean areas, which are prone to heavy rainfall events (Casas et al., 2004).

stable aggregates. Because of their direct relation to cohesive forces, aggregate size and stability are important to understanding soil erosion and surface sealing. Analy- sis of dry aggregates may be used to estimate possible wind-erosion effects, while wet analysis may be more appropriate to evaluate or predict erosion due to rainfall

Soil aggregate stability: a review - agris.fao.org

Soil aggregate stability is a crucial soil property affecting soil sustainability and crop production. A broad outline of the processes and agents of aggregate formation and aggregate stabilization are presented and discussed in this review. Aggregate stability is difficult to quantify and interpret.

Soil aggregate stability was an uncertain predictor of ...

We estimate rangeland managers assessing ecosystem health have measured soil stability >800,000 times. Our aim was to use quantitative data from a site in the Northern Great Plains, USA and a semi‐quantitative literature search to demonstrate the robustness of soil stability as an indicator of ecosystem functioning.

Estimation of soil aggregate stability indices using ...

Estimation of soil aggregate stability in forest`s soils of Guilan province by artificial neural networks and regression pedotransfer functions. Water Soil Sci. 21(3):153-162. Besalatpour AA, Ayoubi S, Hajabbasi MA, Mosaddeghi MR, Schulin R. 2013. Estimating wet soil aggregate stability from easily available properties in a highly mountainous ...

Soil aggregate stability - Wikipedia

Soil aggregate stability is a measure of the ability of soil aggregates to resist degradation when exposed to external forces such as water erosion and wind erosion, shrinking and swelling processes, and tillage (Papadopoulos, 2011; USDA, 2008).

Dry-Soil Aggregate Stability as Influenced by Selected ...

Dry-Soil Aggregate Stability as Influenced by Selected Soil Properties E. L. Skidmore* and J. B. Layton ABSTRACT Dry aggregate stability is an important soil physical property for evaluating tillage and wind-erosion research. Research in this study was aimed at developing a model for predicting soil aggregate stability

17 Aggregate Stability and Size Dlstributlon'

17 Aggregate Stability and Size Dlstributlon' W. D. KEMPER and R. C. ROSENAU Snake River Conservation Research Center Agricultural Research Service, USDA Kimberly, Idaho 17-1 INTRODUCTION 17-1.1 Definition and General Approaches An aggregate is a group of primary particles that cohere to each other more strongly than to other surrounding soil ...

Aggregate-Size Stability Distribution and Soil Stability

accurate determination of aggregate-size stability distribution is pre-Cambardella and Elliott, 1993a; Six et al., 1998) as a sented. The size-stability distribution in addition to estimating aggre- means to study soil aggregates. The capillary-wetted

Soil Aggregates and Associated Organic Matter under ...

Jan 20, 2014· In the current study, the difference in aggregate stability between NT and FS from 5–15 cm is evident in the aggregate stability metric (Figure 1). The stability metric had lower coefficients of variation within a land-use than did either the dry or wet mean-weighted diameter, indicating this metric may be more sensitive to the effects of ...

Aggregate Matchings - its.caltech.edu

Aggregate Matchings Federico Echenique SangMok Lee Matthew Shum y September 25, 2010 Abstract This paper characterizes the testable implications of stability for aggregate matchings. We consider data on matchings where individuals are aggregated, based on their observable characteristics, into types, and we know how many agents of each type match.

Evaluation of methods for determining soil aggregate stability

This study was conducted to (i) explore effects of methodology on values of aggregate stability, (ii) estimate the effects of different wetting fluids on aggregate breakdown, and (iii) provide guidance on selection of methodology and procedures for the determination of aggregate stability of intensively cultivated sandy clay loam and sandy loam ...

Rangeland Soil Quality –Aggregate Stability

What affects aggregate stability? Aggregate stability is affected by soil properties that change relatively little, and by properties that change in response to modifications of vegetation and management. Therefore, management comparisons of aggregate stability should be done within the same soils type (ideal) or texture (acceptable).

Comparison of Regression Pedotransfer Functions and ...

The result, Sk is used as a input for a So called Estimation of soil aggregate stability using RegPTFs activation function such as sigmoid functions yielding the were initially carried out using SPSS 14 for windows with hidden neuron output Hk ( Eq 2). stepwise method.

Soil Aggregate Stability: A Review: Journal of Sustainable ...

Jan 15, 2013· Soil aggregate stability is a crucial soil property affecting soil sustainability and crop production. A broad outline of the processes and agents of aggregate formation and aggregate stabilization are presented and discussed in this review. Aggregate stability is difficult to …