scholarly journals Modelling Alternatives for Highland Soil Structural Degradation and Erodibility, Bui Plateau, Cameroon

2020 ◽  
Vol 1 (6) ◽  
Author(s):  
Reeves M. Fokeng ◽  
Zephania N. Fogwe
Keyword(s):  
Structural Stability ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Stability Index ◽  
Soil Improvement ◽  
Organic Carbon Content ◽  
Soil Biochemistry ◽  
Annual Biomass ◽  
Soil Structural Stability ◽  
Physical Degradation

Highland triggers of soil physical degradation through the fragilisation of soil aggregates are primarily factors of soil biochemistry and anthropogenic mishandling of land resources. Soil degradation forms are challenging the sustenance of human systems on earth. This study probes into soil physical degradation and exposure to external stressors using 60 soil samples collected and analysed for soil aggregate stability, vulnerability and erodibility to determine soil structural stability/resilient capacity. The soils were found to be stable in structure, but highly vulnerable to stress and erodible. Coarse-granitic sandy soils just as the less evolved erosion soils of the eastern slopes of the plateau were proven to be most erodible and vulnerable to physical degradation. Soil Structural Stability Index (ISS) was very low (≤ 4.3%: severe physical degradation) for disturbed soils under grazing with similar tendencies on cultivated humid volcanic soils. High erosion vulnerability/erodibility soils are indicative of low organic matter and organic carbon content issuant of heavy and uncontrolled grazing, annual biomass burning and long-term cropping without soil improvement schemes which calls for guided land use practices over the Bui Plateau.

scholarly journals Fast immersion to test the stability of aggregates in water: consequences for interpreting results from tropical soil classes

2019 ◽  
Vol 42 ◽  
pp. e42453
Author(s):  
Rodrigo Fonseca da Silva ◽  
Patriciani Estela Cipriano ◽  
Matias Siueia Junior ◽  
Geslin Mars ◽  
Moacir de Souza Dias Junior
Keyword(s):  
Soil Aggregates ◽  
Geometric Mean ◽  
Weighted Average ◽  
Aggregate Stability ◽  
Stability Index ◽  
Average Diameter ◽  
Tropical Soils ◽  
Organic Carbon Content ◽  
Pre Treatment ◽  
High Organic Carbon Content

Aggregates are the primary structural components of soil and have been used as an indicator of soil quality in conservation systems. The objective of this study was to analyse the effect of slow pre-wetting on the results of the aggregate stability test for different classes of tropical soils. Data were arranged in a 2 x 4 factorial design with three replications, in which the first factor comprised the two methods of pre-treatment on soil aggregates: without pre-wetting (WOPW), which considered the moisture of the aggregates in the field, and with pre-wetting (WPW), which considered the slow wetting of aggregates through capillarity on wet filter paper for 24h. The second factor consisted of four soil classes: Typic Dystrustept (Cambissolo Aplico distrófico in Embrapa), Typic Hapludult (Argissolo Amarelo distrófico), Rhodic Kandiudult (Nitossolo Vermelho distrófico), and Anionic Acrudox (Latossolo Vermelho distróferrico) and considered horizons A and B. The pre-wetting significantly increased the values of the weighted average diameter, geometric mean diameter and aggregate stability index. In soils with high organic carbon content, the practice of pre-moistening did not provide variation in aggregation.

scholarly journals Do different arbuscular mycorrhizal fungi affect the formation and stability of soil aggregates?

2019 ◽  
Vol 43 ◽  
Author(s):  
Marisângela Viana Barbosa ◽  
Daniela de Fátima Pedroso ◽  
Nilton Curi ◽  
Marco Aurélio Carbone Carneiro
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Stability Index ◽  
Arbuscular Mycorrhizal ◽  
Soil Aggregate ◽  
Porous Space ◽  
Soil Aggregate Stability ◽  
The Mean

ABSTRACT Soil structure, which is defined by the arrangement of the particles and the porous space forming aggregates, is one of the most important properties of the soil. Among the biological factors that influence the formation and stabilization of soil aggregates, arbuscular mycorrhizal fungi (AMF) are distinguished due to extrarradicular hyphae and glomalin production. In this context, the objective of this study was to evaluate different AMF (Acaulospora colombiana, Acaulospora longula, Acaulospora morrowiae, Paraglomus occultum and Gigaspora margarita) associated with Urochloa brizantha (A. Rich.) Stapf on soil aggregate stability. The study was conducted in a completely randomized design, using an Oxisol and autoclaved sand 2:1 (v/v), with seven treatments: five AMF; and treatments with plants without inoculation and with only the soil, with 5 replicates. The experiment was conducted during 180 days and the following variables were evaluated: mycelium total length (TML); production of easily extractable glomalin-related soil protein (GRSP) in the soil and aggregate classes; stability of the dry and immersed in water aggregates through the mean geometric diameter (MGD) and the mean weighted diameter (MWD) of aggregates; and the soil aggregate stability index (ASI). It was observed that the inoculation favored soil aggregation, with a high incidence of A. colombiana, which presented the highest MGD, TML and GRSP production in the aggregates with Ø>2.0mm and for A. colombiana and A. morrowiae in the aggregates with Ø<0.105 mm, when compared to the treatment without inoculation. These results show that there is a distinction between the effects of different AMF on the formation and stability of soil aggregates.

Amending soil with sludge, manure, humic acid, orthophosphate and phytic acid: effects on aggregate stability

Soil Research ◽  
2014 ◽  
Vol 52 (4) ◽  
pp. 317 ◽  
Author(s):  
A. I. Mamedov ◽  
B. Bar-Yosef ◽  
I. Levkovich ◽  
R. Rosenberg ◽  
A. Silber ◽  
...  
Keyword(s):  
Humic Acid ◽  
Phytic Acid ◽  
Structural Stability ◽  
Organic Amendments ◽  
Aggregate Stability ◽  
Loamy Sand ◽  
Soil Aggregate Stability ◽  
Before And After ◽  
Soil Structural Stability ◽  
The Stability

Recycling of organic wastes via their incorporation in cultivated lands is known to alter soil structural stability. Aggregate stability tests are commonly used to express quantitatively the susceptibility of soil structural stability to deformation. The objective of this study was to investigate the effects of biosolids addition, namely composted manure (MC) and activated sludge (AS), and spiking of the soils with orthophosphate (OP), phytic acid (PA) or humic acid (HA), on soil aggregate stability of semi-arid loamy sand, loam and clay soils before and after subjecting the soils to six rain storms (each 30 mm rain with a break of 3–4 days). Aggregate stability was determined from water-retention curves at high matric potential. The effects of the applied amendments on pre- and post-rain aggregate stability were inconsistent and soil-dependent. For the pre-rain state, all of the tested amendments improved aggregate stability relative to the control. For the post-rain condition, aggregate stability was lower in the MC, OP and PA treatments and higher in the AS and HA treatments than in the control. The coarse-textured loam and loamy sand soils were more affected by the soil amendments than the clay soil. For the pre-rain state, addition of organic matter significantly improved macro-porosity and hence the stability of apparent macro-aggregate (>250 μm). Our results indicate a possible advantage for separation of aggregates into macro- and micro-aggregates for more precise evaluation and understanding of the effects organic amendments might have on aggregate stability.

Comparison of the effects of latex and poly(DADMAC) on structural stability and strength of soil aggregates

Soil Research ◽  
1995 ◽  
Vol 33 (2) ◽  
pp. 369 ◽  
Author(s):  
SM Bernas ◽  
JM Oades ◽  
GJ Churchman ◽  
CD Grant
Keyword(s):  
Structural Stability ◽  
Cropping Systems ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Structural Condition ◽  
Mechanical Action ◽  
Water Stable Aggregates ◽  
The Face ◽  
Wet Aggregate Stability ◽  
Aromatic Oils

Two types of high molecular weight polymers having contrasting charge properties and molecular shapes [latex and poly(DADMAC)] were applied at different rates to three Alfisols and a Mollisol to examine the effects of these polymers on soil strength and structural stability, and to identify some of the mechanisms by which these polymers act to stabilize soils. Wet aggregate stability, mechanically dispersible clay, and soil friability tests were used to assess treatment effects, which were found to be greatest in soils having a poor structural condition. Each polymer acted differently. Latex, which acted like a coat of paint (because of its inability to penetrate beyond the surface of aggregates), dramatically increased the proportion of water stable aggregates >2 mm in all soils examined, and this was achieved without the traditional (expensive) use of aromatic oils and stabilizers. The latex coating produced a conglomeration of smaller soil aggregates, but did not extensively alter either the dispersibility of the aggregates in the face of mechanical action, or their strength and friability. Results indicate latex may be best suited to minimum tillage cropping systems. Poly(DADMAC), by contrast, was capable of entering most pores accessible to water. This enabled it to minimize clay dispersion, increase soil friability, and to modestly increase the size of water stable aggregates. In many ways, poly(DADMAC) would appear to be an ideal soil conditioner, although the economic suitability of this polymer and its effects on erosion control and plant growth have yet to be assessed.

Freezing cycle effects on water stability of soil aggregates

2013 ◽  
Vol 93 (4) ◽  
pp. 473-483 ◽  
Author(s):  
Daryl F. Dagesse
Keyword(s):  
Water Content ◽  
Structural Stability ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Clay Content ◽  
Initial Water Content ◽  
Water Stability ◽  
Initial Water ◽  
Freeze Thaw ◽  
Freezing Cycle

Dagesse, D. F. 2013. Freezing cycle effects on water stability of soil aggregates. Can. J. Soil Sci. 93: 473–483. The freezing process is commonly implicated as a key factor in defining the state of soil structural stability following the winter months. Controversy exists, however, regarding the efficacy, and even the net effect, of this process. The objective of the study was to establish the separate effects of the freezing, freeze–thaw and freeze-drying processes in defining soil structural stability following the over-winter period. Aggregates from soils of varying clay content (0.11, 0.33, 0.44 kg kg−1) and initial water content (0.10, 0.20 or 0.30 kg kg−1) were subjected to freeze-only (F), freeze–thaw (FT) and freeze-dry (FD) treatments. Post-treatment aggregate stability determination was via wet aggregate stability (WAS) and dispersible clay (DC). Freezing alone and freeze-dry treatments generally resulted in greater aggregate stability, while the freeze–thaw generally resulted in lower aggregate stability as compared with a control, not frozen treatment (T). These data suggest the freezing-induced desiccation process improves aggregate stability, while the addition of a thaw component following freezing, with the attendant liquid water, is responsible for degradation of aggregate stability. Clay content and initial water content are important factors governing the magnitude of this process.

The influence of different cover crop residues quantities on soil structural stability

2021 ◽  
Author(s):  
Gheorghe Stegarescu ◽  
Endla Reintam ◽  
Tõnu Tõnutare
Keyword(s):  
Soil Moisture ◽  
Structural Stability ◽  
Cover Crop ◽  
Crop Residues ◽  
Aggregate Stability ◽  
Soil Aggregate ◽  
Incubation Experiment ◽  
Soil Aggregate Stability ◽  
Substrate Induced Respiration ◽  
Soil Structural Stability

&lt;p&gt;Cover crops are widely known for their capacity to improve the soil biological properties and soil structural stability. Nevertheless, the cover crop residues quantity necessary to improve these soil properties is not yet really known. A 30-day incubation experiment was conducted to explore the effect of oilseed rape (Brassica napus) residues (ORR) as a cover crop on the soil aggregate stability of sandy loam soil. The fresh ORR was mixed with the soil at different rates starting from 1.0 to 6.0 g C kg&lt;sup&gt;-1&lt;/sup&gt; of soil. The experiment consisted of five treatments: bulk soil (I), soil mixed with ORR at a rate of 1 g C kg&lt;sup&gt;-1&lt;/sup&gt; of soil (II), soil mixed with ORR at a rate of 2 g C kg&lt;sup&gt;-1&lt;/sup&gt; of soil (III), soil mixed with ORR at a rate of 4 g C kg&lt;sup&gt;-1&lt;/sup&gt; of soil (IV), soil mixed with ORR at a rate of 6 g C kg&lt;sup&gt;-1&lt;/sup&gt; of soil (V). During 30 days of incubation the soil moisture, soil water stable aggregates, and microbial substrate induced respiration rates were measured. The aggregate stability significantly increased after 30 days only in the treatment with 1 g C kg&lt;sup&gt;-1&lt;/sup&gt; of soil. In turn, the ORR applied at a rate of 6 g C kg&lt;sup&gt;-1&lt;/sup&gt; of soil significantly decreased the soil aggregate stability. The higher the ORR addition rate the lower was the soil basal respiration and substrate induced respiration. The general conclusion was that the higher quantity of ORR increased the soil moisture which subsequently created unfavorable conditions for the soil microbial activity and led to soil aggregate stability degradation. However, this conclusion must be validated in a field study where the soil moisture and temperature conditions are much more variable compared to our incubation experiment.&lt;/p&gt;

scholarly journals Effectiveness of wheat straw mulch and Polyacrylamide on shallow stability of roadside slopes  

2019 ◽  
Vol 65 (No. 11) ◽  
pp. 445-449
Author(s):  
Aidin Parsakhoo ◽  
Seyed Jamal Mirniazi ◽  
Ayoob Rezaee Motlaq
Keyword(s):  
Wheat Straw ◽  
Clay Soil ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Stability Index ◽  
Bare Soil ◽  
Efficient Treatment ◽  
Straw Mulch ◽  
Mean Weight Diameter ◽  
Wheat Straw Mulch

Soil aggregate instability on unprotected roadside slopes can cause landslide, soil erosion and sedimentation. Different biological and chemical soil stabilizers are used to reinforce the instable slopes. In the present study, straw mulch and Polyacrylamide (PAM) combinations were investigated on a clay soil of road cutslope in campus of Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. The selected cover treatments were Polyacrylamide (2, 3 and 4 g·m–2) with wheat straw mulch (50, 150 and 250 g·m–2) which was spread by hand to attain 75% groundcover on a 1:1 slope. After the three months, soil sampling was done to determine the changes in aggregate stability of soil. Results showed that the most efficient treatment with respect to mean weight diameter of soil aggregates in dry and wet sieving (MWDdry and MWDwet), aggregate stability index (AS) and aggregate destruction index (DI) was treatment of B (150 g·m–2 wheat straw mulch and 3 g·m–2 Polyacrylamide tackifier) with 34%, 68% and 47% increment in MWDdry, MWDwet and AS, respectively as well as 37% reduction in DI as compared to the bare soil control.<br /><br />

scholarly journals  Influence of terrain attributes and soil properties on soil aggregate stability

2011 ◽  
Vol 6 (No. 3) ◽  
pp. 111-119 ◽  
Author(s):  
T. Zádorová ◽  
O. Jakšík ◽  
R. Kodešová ◽  
V. Penížek
Keyword(s):  
Soil Properties ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Structure Stability ◽  
Organic Carbon Content ◽  
Terrain Attributes ◽  
Erosion Processes ◽  
Digital Elevation ◽  
Curvature Index ◽  
Elevation Model

&nbsp; The study on the relationship between the soil aggregates stability assessed using water stable aggregate (WSA) index and the selected terrain and soil properties was performed on a morphologically diverse study site in Chernozem soil region of Southern Moravia. Soil analyses and detailed digital elevation model processing were the main methods adopted in the study. The soil structure stability is negatively influenced by the soil material removal from the steep parts of the back-slope and re-deposition of the mineral loess material at the base of the slope. The highest aggregates stability was identified in the upper flat parts of the study plot, undisturbed by erosion processes, and at the concave parts of the back-slope with intensive accumulation of organic matter. Statistical analysis showed a significant dependence of aggregates stability on organic carbon content and plan curvature index.

INFLUENCE OF ICE SEGREGATION AND SOLUTES ON SOIL STRUCTURAL STABILITY

1990 ◽  
Vol 70 (4) ◽  
pp. 571-581 ◽  
Author(s):  
E. PERFECT ◽  
W. K. P. van LOON ◽  
B. D. KAY ◽  
P. H. GROENEVELT
Keyword(s):  
Water Content ◽  
Structural Stability ◽  
Aggregate Stability ◽  
Frost Heave ◽  
Unfrozen Water Content ◽  
Soil Structural Stability ◽  
Frost Penetration ◽  
Wet Aggregate Stability ◽  
Dispersible Clay ◽  
Ice Segregation

Most Canadian soils contain dissolved salts and are subject to freezing. However, the structural consequences of freezing in the presence of solutes are unknown. The effects of ice segregation and solutes on soil structural stability were investigated in a laboratory experiment. Nine 27-cm-diameter by 19-cm-high columns were used. These were packed with air-dry Conestogo silt loam soil (Gleyed Melanic Brunisol or Aquic Eutrochrept) and wetted with CaCl2 solutions at 1, 2, and 4 g L−1. Slow freezing took place from the top down in an environmental chamber maintained at −3.4 ± 0.4 °C. Depth of frost penetration, temperature, frost heave, and unfrozen water content were monitored within each column. After 20 d, the mean frost penetration was 107 ± 18 mm and the soil surface had heaved 9 ± 4 mm, indicating ice segregation. At the end of the experiment, the frozen and unfrozen zones of each column were sampled destructively. Samples were equilibrated at 4 °C and analyzed for wet-aggregate stability (WAS), dispersible clay (DC), gravimetric water content, and CaCl2 concentration. Samples which had been frozen had significantly more water and CaCl2 in the thawed state than those which had remained unfrozen. These increases were attributed to a freezing-induced redistribution of the saturating solutions. DC decreased with increasing CaCl2 concentration, indicating an electrical double-layer effect. Soil that had been frozen and thawed had a more stable structure (in terms of both DC and WAS) than the unfrozen soil. No interaction was found between solutes and freezing. In contrast, there was a significant interaction between water content and freezing. WAS increased with decreasing water content for those aggregates which had been frozen and thawed, but not for those which had remained unfrozen. Key words: Soil structure, wet-aggregate stability, dispersible clay, frost heave, soil solution, bulk electrical conductivity

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