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.

scholarly journals Tillage Intensity Effects on Soil Structure Indicators—A US Meta-Analysis

2020 ◽  
Vol 12 (5) ◽  
pp. 2071 ◽  
Author(s):  
Márcio R. Nunes ◽  
Douglas L. Karlen ◽  
Thomas B. Moorman
Keyword(s):  
Crop Production ◽  
Soil Structure ◽  
Management Practices ◽  
Cropping Systems ◽  
Meta Analysis ◽  
Soil Health ◽  
Health Assessment ◽  
Aggregate Stability ◽  
Soil Penetration Resistance ◽  
Wet Aggregate Stability

Tillage intensity affects soil structure in many ways but the magnitude and type (+/−) of change depends on site-specific (e.g., soil type) and experimental details (crop rotation, study length, sampling depth, etc.). This meta-analysis examines published effects of chisel plowing (CP), no-tillage (NT) and perennial cropping systems (PER) relative to moldboard plowing (MP) on three soil structure indicators: wet aggregate stability (AS), bulk density (BD) and soil penetration resistance (PR). The data represents four depth increments (from 0 to >40-cm) in 295 studies from throughout the continental U.S. Overall, converting from MP to CP did not affect those soil structure indicators but reducing tillage intensity from MP to NT increased AS in the surface (<15-cm) and slightly decreased BD and PR below 25-cm. The largest positive effect of NT on AS was observed within Inceptisols and Entisols after a minimum of three years. Compared to MP, NT had a minimal effect on soil compaction indicators (BD and PR) but as expected, converting from MP to PER systems improved soil structure at all soil depths (0 to >40-cm). Among those three soil structure indicators, AS was the most sensitive to management practices; thus, it should be used as a physical indicator for overall soil health assessment. In addition, based on this national meta-analysis, we conclude that reducing tillage intensity improves soil structure, thus offering producers assurance those practices are feasible for crop production and that they will also help sustain soil resources.

Comparison of four prewetting techniques in wet aggregate stability determination

1991 ◽  
Vol 71 (1) ◽  
pp. 67-72 ◽  
Author(s):  
E. L. Dickson ◽  
V. Rasiah ◽  
P. H. Groenevelt
Keyword(s):  
Key Words ◽  
Coefficient Of Variation ◽  
Treatment Effects ◽  
Soil Aggregates ◽  
High Vacuum ◽  
Aggregate Stability ◽  
Gas Pressure ◽  
Wet Aggregate Stability ◽  
Wetting Rate

Variabilities in measured values of wet aggregate stability (WAS) of replicate samples of treatment exceeding that between treatments can create problems in interpreting treatment effects. The variabilities in WAS of replicate samples of treatment can be minimized by subjecting soil aggregates to a high vacuum fast prewetting technique. However, this technique is laborious and time consuming. In this paper the effect of four prewetting techniques: (1) and (2) high vacuum fast (HVFW) and slow (HVSW) wetting; (3) and (4) no vacuum (atmospheric) fast (NVFW) and slow wetting (NVSW) on the variations in WAS and coefficient of variation (CV) of WAS are reported. The measured values in WAS and CV of WAS for each soil varied with wetting rate and/or gas pressure used. The highest variation in WAS was found with NVFW, HVFW, NVSW and HVSW, respectively. For three out of four soils, the CV of WAS for NVSW technique was less than 2%, which was similar to that obtained under HVFW technique. Compared to HVFW technique, NVSW technique is simple, less laborious and less time consuming. Key words: Wet aggregate stability, prewetting techniques, vacuum wetting.

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.

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.

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

RELATIONS BETWEEN AGGREGATE STABILITY AND ORGANIC COMPONENTS FOR A SILT LOAM SOIL

1990 ◽  
Vol 70 (4) ◽  
pp. 731-735 ◽  
Author(s):  
E. PERFECT ◽  
B. D. KAY
Keyword(s):  
Organic Carbon ◽  
Crop Production ◽  
Cropping Systems ◽  
Aggregate Stability ◽  
Organic Carbon Content ◽  
Active Components ◽  
Rates Of Change ◽  
Loam Soil ◽  
Organic Carbon Pool ◽  
Wet Aggregate Stability

Rates of change in wet-aggregate stability under different cropping systems have been reported. These data were used to infer rates of change in the amount of stabilizing materials present. Increases in wet-aggregate stability did not correlate with increases in total organic carbon content, suggesting that some components of the organic carbon pool are more actively involved in stabilizing aggregates than others. Assuming a linear relation between these active components and wet-aggregate stability, the amount of stabilizing materials present should increase exponentially with time when forages are introduced onto soil previously used for row crop production. Key words: Soil structure, wet-aggregate stability, organic matter, corn, forages

scholarly journals Seasonal Changes of Soil Quality Indicators in Selected Arid Cropping Systems

Agriculture ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 124 ◽  
Author(s):  
Mohammed Omer ◽  
Omololu Idowu ◽  
April Ulery ◽  
Dawn VanLeeuwen ◽  
Steven Guldan
Keyword(s):  
Soil Quality ◽  
Quality Indicators ◽  
Management Practices ◽  
Cropping Systems ◽  
Aggregate Stability ◽  
Crop Management ◽  
Soil Bulk Density ◽  
Soil Quality Indicators ◽  
Soil Measurements ◽  
Wet Aggregate Stability

Improving the soil quality in arid agro-ecosystems requires a greater understanding of how the time-of-sampling and management affect the soil measurements. We evaluated the selected soil quality indicators on samples collected at a 0–0.15 m depth, and at various sampling dates of the year, corresponding to the fall of 2015, winter of 2015/2016, spring of 2016, and the summer of 2016. The three crop management systems sampled included alfalfa (Medicago sativa), upland cotton (Gossypium hirsutum), and pecan (Carya illinoinensis). The soil properties measured included the wet aggregate stability (WAS), mean weight diameter of dry aggregates (MWD), dry aggregates greater than 2 mm (AGG >2 mm), dry aggregates less than 0.25 mm (AGG <0.25 mm), available water capacity (AWC), soil organic matter (SOM), permanganate oxidizable carbon (POXC), soil bulk density (BD), soil electrical conductivity (EC), pH, nitrate-nitrogen (NO3-N), extractable potassium (K), extractable phosphorus (P), calcium (Ca), magnesium (Mg), sodium adsorption ratio (SAR), and micronutrients (zinc, iron, copper, and manganese). Out of the 21 soil measurements, 15 varied significantly with the time-of-sampling within a year, although there were no consistent trends in variability. However, only a few measurements differed significantly with the crop management practices tested. Wet aggregate stability, MWD, AWC, and BD were significantly higher in the summer, while POXC and SOM were significantly higher in the fall and winter, respectively. Soil quality indicators such as NO3-N, K, and P decreased significantly during the spring. This study shows that the seasonal variability of the soil measurements can be significant in the arid agro-ecosystems, with the magnitude of variation depending on the measurement type. The soil managers in the region need to account for this variability, in order to be able to assess the changes in the soil quality. Also, because of the variability that can occur across the different sampling dates within a year, it is advisable to sample during the same period every year, for a consistent interpretation of the directional changes of the soil quality indicators.

EFFECT OF ROOT EXUDATES FROM CORN AND BROMEGRASS ON SOIL STRUCTURAL STABILITY

1990 ◽  
Vol 70 (3) ◽  
pp. 351-362 ◽  
Author(s):  
T. POJASOK ◽  
B. D. KAY
Keyword(s):  
Structural Stability ◽  
Root Exudates ◽  
Soil Structure ◽  
Aggregate Stability ◽  
Clay Content ◽  
Flash Evaporation ◽  
Metal Organic ◽  
Loam Soil ◽  
Wet Aggregate Stability ◽  
Dispersible Clay

The effect of root exudates on structural stability and the hypothesis that the growing roots of corn (Zea mays L.) can destabilize soil structure by chelating Fe and Al involved in mineral-metal-organic matter linkages were investigated. Exudates were removed from 14C-labelled corn and bromegrass (Bromus inermis Leyss.) plants grown in sand using sequential leaching with water and acetone. The exudates were concentrated by flash evaporation and incubated with 1–2 mm aggregates of a calcareous silt loam soil for up to 240 h. Aggregates to which exudates from bromegrass were added had a higher wet aggregate stability (WAS) and lower dispersible clay content (DC) than aggregates to which exudates from corn were added. The greatest increase in stability occurred on addition of the water-extracted exudates (9.6% for WAS, 27.1% for DC). The increase in stability correlated positively with a release into solution of Ca and Mg from the soil solids. Addition of CaCl2 to the aggregates, to give corresponding amounts of Ca and Mg in solution, had similar effects on stability suggesting that the ions released by the exudates were not in a chelated form. The quantity of carbon added in the exudates and the mineralization of this carbon were positively and negatively correlated with stability, respectively. There was little evidence that corn exudates caused a destabilization of structure. Key words: Wet aggregate stability, dispersible clay, corn, bromegrass, flocculation, calcium

WATER-STABLE AGGREGATION IN RELATION TO VARIOUS CROPPING ROTATIONS AND SOIL CONSTITUENTS

1965 ◽  
Vol 45 (2) ◽  
pp. 189-197 ◽  
Author(s):  
M. N. Malik ◽  
D. S. Stevenson ◽  
G. C. Russell
Keyword(s):  
Organic Carbon ◽  
Cropping Systems ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
The Other ◽  
Soluble Salts ◽  
Soil Aggregate Stability ◽  
Soil Constituents

The effects of four cropping systems on water-stable aggregation were compared. Two methods of wetting the soil, (1) by capillarity and (2) under vacuum prior to wet-sieving, were also compared. Various soil constituents were determined to assess their roles in the promotion of granulation and stability. Water-stable aggregation in grassland was significantly higher than in the other three long-term rotations, corn once in 9 years, continuous wheat, and 4 years alfalfa in 10 years. No significant differences in water-stable aggregation were found among the other three rotations.Wetting the soil by capillarity was judged to give a better index of soil aggregate stability than wetting under vacuum. Organic carbon and stable aggregation were positively correlated in the grassland soil and in the soil of the cultural treatments combined over all depths, suggesting an important role of organic matter in stabilization of soil aggregates. It is pointed out, however, that in cultivated soils the cultivation or the type of root system of the crops may override the influence of the organic carbon. Total soluble salts were positively correlated with aggregation in a few treatments.

Structural stability of sodic soils in sugarcane production as influenced by gypsum and molasses

2002 ◽  
Vol 42 (3) ◽  
pp. 315 ◽  
Author(s):  
A. Suriadi ◽  
R. S. Murray ◽  
C. D. Grant ◽  
P. N. Nelson
Keyword(s):  
Structural Stability ◽  
Aggregate Stability ◽  
Clay Loam ◽  
Exchangeable Sodium ◽  
Sodic Soils ◽  
Clay Dispersion ◽  
Sugarcane Production ◽  
Mechanical Dispersion ◽  
Wet Aggregate Stability ◽  
Dispersible Clay

The aim of this work was to determine whether molasses, a by-product of sugar manufacture, alone or combined with gypsum, could improve the structural stability of sodic soils used for sugarcane production. A Burdekin sandy clay loam with an exchangeable sodium percentage (ESP) of 7.9, and a Proserpine loamy sand with an ESP of 18.8 were incubated with molasses (0 and 10 t/ha) and gypsum (0 and 10 t/ha) for 12 weeks, during which time they were leached 5 times with water (0.5 pore volumes each time). In the Burdekin soil, molasses and gypsum, either alone or combined, decreased spontaneous clay dispersion from 2.6 to <0.2 g/kg soil. Mechanical dispersion was reduced from 21.2 to <0.2 g/kg soil by gypsum alone, and to 14.9 g/kg soil by molasses alone. Molasses and gypsum both increased wet aggregate stability, with the combined effect being greatest; the proportion of aggregates >250 μm was 31% in the control and 71% with molasses + gypsum. Electrical conductivity (EC 1:5) was 0.1 and 1.9 dS/m, pH1:5 in water was 7.7 and 7.1, and ESP was 4.1 and 0.2 in the control and molasses + gypsum treatments respectively. In the Proserpine soil, the amounts of dispersible clay were much less than in the Burdekin soil. The effects of molasses and gypsum in decreasing spontaneous and mechanical clay dispersion were similar to those in the Burdekin soil, but less pronounced. Molasses and gypsum, either alone or combined, improved the structural stability of both soils by decreasing dispersion and/or slaking. An implication of this work is that molasses may be a useful ameliorant for sodic soils, either alone or combined with gypsum.

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