Evaluation of the 137Cs techniques for estimating wind erosion losses for some sandy Western Australian soils

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1369 ◽  
Author(s):  
RJ Harper ◽  
RJ Gilkes
Keyword(s):  
Organic Carbon ◽  
Wind Erosion ◽  
Sandy Soils ◽  
Clay Content ◽  
Organic Carbon Content ◽  
137Cs Content ◽  
Near Surface ◽  
Mean Values ◽  
Significant Difference ◽  
Mean Grain Size

The utility of the caesium-137 (137Cs) technique, for estimating the effects of wind erosion, was evaluated on the soils of a semi-arid agricultural area near Jerramungup, Western Australia. The past incidence of wind erosion was estimated from field observations of soil profile morphology and an existing remote sensing study. Erosion was limited to sandy surfaced soils (0-4% clay), with a highly significant difference (P < 0.0001) in 137Cs values between eroded and non-eroded sandy soils, with mean values of 243 � 17 and 386 � 13 Bq m-2 respectively. Non-eroded soils, with larger clay contents, had a mean 137Cs scontent of 421 � 26 Bq m-2, however, due to considerable variation between replicate samples, this value was not significantly different from that of the non-eroded sands. Hence, although the technique discriminates between eroded and non-eroded areas, the large variation in 137Cs values means that from 27 to 96 replicate samples are required to provide statistically valid estimates of 137Cs loss. The occurrence of around 18% of the total 137Cs between 10 and 20 cm depth in these soils, despite cultivation being confined to the surface 9 cm, suggests that leaching of 137Cs occurs in the sandy soils, although there was no relationship between clay content and 137Cs value for either eroded or non-eroded soils. In a multiple linear regression, organic carbon content and the mean grain size of the eroded soils explained 35% of the variation in 137Cs content. This relationship suggests that both organic carbon and 137Cs are removed by erosion, with erosion being more prevalent on soils with a finer sand fraction. Clay and silt contents do not vary with depth in the near-surface horizons of the eroded sandy soils, hence it is likely that wind erosion strips the entire surface horizon with its 137Cscontent, rather than selectively winnowing fine material.

Sorption of Anionic Pentachlorophenol (PCP) in Aquatic Environments: The Effect of pH

1992 ◽  
Vol 25 (11) ◽  
pp. 41-48 ◽  
Author(s):  
Y. Shimizu ◽  
S. Yamazaki ◽  
Y. Terashima
Keyword(s):  
Organic Carbon ◽  
Aqueous Phase ◽  
Cation Exchange Capacity ◽  
Clay Content ◽  
Exchange Capacity ◽  
Poor Correlation ◽  
Aquatic Environments ◽  
Organic Carbon Content ◽  
Swelling Clay ◽  
Ph Range

The sorption of pentachlorophenol (PCP, pKa’ = 4.75) onto natural solids from aqueous phase was investigated by batch sorption experiments. The experimental aqueous phase was prepared for set values of pH (2 to 12) and ionic strength (0.1 M). Experimental results indicated that the sorption decreased with increasing pH over the entire pH range tested. A simple mathematical model, based on the hypotheses that the sorption coefficients of non-ionized and ionized species are different and the pH has only negligible effect on the natural solid characteristics, was applied to the pH range between 6 and 8, and the sorption coefficients (Kd) of both species were estimated. The Kd of ionized species (phenolate anion) was smaller than that of non-ionized species. The Kd of both species had poor correlation to the organic carbon content of natural solids. The Kd, however, correlated well with the swelling clay content and cation exchange capacity of natural solids. These results indicated that the sorption of PCP was not controlled by the organic carbon referenced hydrophobic sorption. For broader pH range (i.e., below 6 or above 8), the dependence of the natural solid characteristics on pH must be additionally included in the model.

Changes in dispersible clay content, organic carbon content, and electrolyte composition following incubation of sodic soil

Soil Research ◽  
1998 ◽  
Vol 36 (6) ◽  
pp. 883 ◽  
Author(s):  
P. N. Nelson ◽  
J. A. Baldock ◽  
J. M. Oades
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Water Content ◽  
Clay Content ◽  
Electrolyte Composition ◽  
Organic Carbon Content ◽  
Sodic Soils ◽  
Sodic Soil ◽  
Clay Dispersion ◽  
Dispersible Clay

Measurement of dispersible clay is important for the diagnosis of structural stability problems in soil. However, clay dispersibility is known to change with water content and time. The purpose of the present study was to determine how incubation of sodic soil under different water content regimes influences clay dispersibility. Two topsoils (depth 0-0·1 m), one sodic [exchangeable sodium percentage (ESP) 9 · 7] and the other non-sodic (ESP 3·8), were collected from an experimental pasture at Kyabram, Victoria, and 2 soils, a sodic topsoil (depth 0-0·1 m, ESP 6·9) and the corresponding subsoil (depth 0·2-0 m, ESP 25·7), were collected from a cropped field at Two Wells, South Australia. The soils were incubated for 264 days in a split-plot design. The main treatments were soil type and incubation water content: continuously air-dry, continuously wet (-50 kPa), or with wet/dry cycles. The subtreatment was water content at analysis: air dry or wet (-50 kPa). Clay dispersion was greater when measured on wet soils than dry soils, irrespective of water contents during the prior incubation. Electrical conductivity increased, and sodium adsorption ratio (SAR), pH, and organic carbon content decreased as a function of the time for which the soils were wet. In the Kyabram soils that were wet when analysed, easily dispersible clay content increased with SAR. Decreases in moderately dispersible clay under the wetting/drying regime were not related to electrolyte composition, and were attributed to particle rearrangement and cementation. The decreases in clay dispersibility with time occurred despite net losses of carbohydrate and aliphatic materials. An implication of the work is that the decomposition of soil organic matter, even in the absence of fresh additions, may reduce clay dispersion in sodic soils by altering electrolyte concentration and composition.

Extraction of compounds associated with water repellency in sandy soils of different origin

Soil Research ◽  
2005 ◽  
Vol 43 (3) ◽  
pp. 225 ◽  
Author(s):  
S. H. Doerr ◽  
C. T. Llewellyn ◽  
P. Douglas ◽  
C. P. Morley ◽  
K. A. Mainwaring ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Sandy Soils ◽  
Water Repellency ◽  
Organic Carbon Content ◽  
Soil Water Repellency ◽  
Diverse Range ◽  
Additional Information ◽  
The Uk

After an initial evaluation of several solvents, the efficiency of Soxhlet extractions with isopropanol/ammonia (s.g. 0.88) (70 : 30 v : v; 24 h) in extracting compounds associated with water repellency in sandy soils was examined using a range of repellent and wettable control soils (n = 15 and 4) from Australia, Greece, Portugal, The Netherlands, and the UK. Extraction efficiency and the role of the extracts in causing soil water repellency was examined by determining extract mass, sample organic carbon content and water repellency (after drying at 20°C and 105°C) pre- and post-extraction, and amounts of aliphatic C–H removed using DRIFT, and by assessing the ability of extracts to cause repellency in acid-washed sand (AWS). Key findings are: (i) none of organic carbon content, amount of aliphatic C–H, or amount of material extracted give any significant correlation with repellency for this diverse range of soils; (ii) sample drying at 105°C is not necessarily useful before extraction, but may provide additional information on extraction effectiveness when used after extraction; (iii) the extraction removed repellency completely from 13 of the 15 repellent samples; (iv) extracts from all repellent and wettable control soils were capable of inducing repellency in AWS. The findings suggest that compounds responsible for repellency represent only a fraction of the extract composition and that their presence does not necessarily always cause repellency.

Binding of water-extractable organic carbon to clay subsoil: effects of clay subsoil properties

Soil Research ◽  
2015 ◽  
Vol 53 (1) ◽  
pp. 81 ◽  
Author(s):  
Shinhuey Lim ◽  
Trung-Ta Nguyen ◽  
Petra Marschner
Keyword(s):  
Organic Carbon ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sandy Soils ◽  
Clay Content ◽  
Sodium Absorption ◽  
Oxide Content ◽  
Relative Importance ◽  
Water Extractable

Addition of clay-rich subsoils to sandy soils can increase yield and may increase organic carbon (OC) retention in soils. The ability of clays to bind OC is likely to be influenced by clay properties, but little is known about the relative importance of properties of clay subsoils for binding of OC. A batch sorption experiment was conducted using seven clay subsoils collected from agricultural lands where claying was carried out. Clay subsoils were shaken for 17 h at 4°C with different concentrations of water-extractable OC (WEOC: 0, 2.5, 5.0, 7.5, and 9.0 g kg–1 soil) derived from mature wheat (Triticum aestivum L.) straw at a 1 : 10 soil : extract ratio. Sorption of WEOC was positively correlated with clay content, specific surface area and concentration of iron oxides. Further, WEOC sorption was negatively correlated with total OC content, sodium absorption ratio and cation ratio of soil structural stability. However, the relative importance of these properties for WEOC sorption differed among soils. In conclusion, OC retention in clay-amended sandy soils will be positively related to clay soil properties such as clay and Fe oxide content and specific surface area.

scholarly journals Determination of soil specific surface area by water vapor adsorption: III Comparison of surface areas determined by water vapor and nitrogen gas adsorption

1988 ◽  
Vol 60 (2) ◽  
pp. 73-79
Author(s):  
Raina Niskanen ◽  
Väinö Mäntylahti
Keyword(s):  
Water Vapor ◽  
Organic Carbon ◽  
Gas Adsorption ◽  
Clay Content ◽  
Water Area ◽  
Water Vapor Sorption ◽  
Organic Carbon Content ◽  
Vapor Sorption ◽  
Nitrogen Gas ◽  
Surface Areas

The specific surface areas of ten soil samples (clay content 1—72 %, organic carbon content 0.8—11.5 %) were determined by water vapor and nitrogen gas adsorption. The surface areas obtained by application of the BET equation to water vapor sorption at p/po 0.12—0.42 (21—195 m2/g) were, on the average, 80 % of the areas determined by water vapor sorption at p/po 0.20, range 27—229 m2/g. A BET water monolayer coverage was formed on the soil surface at p/po 0.12—0.20. The BET water area correlated closely with the one-point water area (p/po 0.20). The surface area determined by nitrogen gas adsorption ranged from 0.3 to 21 m2/g and did not correlate closely with water areas. The water surface areas were closely related to soil organic carbon content, while the nitrogen area was primarily related to soil clay content.

scholarly journals Determination of soil specific surface area by water vapor adsorption: I Drying of soil samples

1987 ◽  
Vol 59 (2) ◽  
pp. 63-65
Author(s):  
Raina Niskanen ◽  
Väinö Mäntylahti
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Mineral Soil ◽  
Clay Content ◽  
Fine Sand ◽  
Water Vapor Adsorption ◽  
Soil Samples ◽  
Organic Carbon Content ◽  
Clay Sample

Drying of three mineral soil samples (clay content 4—58 %, organic carbon content 1—5 %) equilibrated at 75.5 % relative humidity was studied. The soils were dried in an oven at +50°C, +70°C and + 105°C for 4 and 8 hours and in a desiccator over pure concentrated H2SO4 and P2O5. Drying over desiccants for 8 hours removed less water than drying at + 50°C. Drying over desiccants for 3—7 days was as efficient as drying at +70°C, for 14—24 days as efficient as 4 hours of drying at + 105°C. Eight hours of drying at + 105°C seemed to be too drastic, because it caused a greater weight loss in the clay sample of 5 % organic carbon content than did prolonged desiccant-drying. Drying at + 70°Cremoved as much water from fine sand which contained 4 % clay as prolonged desiccant-drying.

scholarly journals Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

2016 ◽  
Author(s):  
O. Serrano ◽  
P. S. Lavery ◽  
C. M. Duarte ◽  
G. A. Kendrick ◽  
A. Calafat ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Clay Content ◽  
Cost Effective ◽  
Blue Carbon ◽  
Organic Carbon Content ◽  
Terrestrial Organic Matter ◽  
Seagrass Meadows ◽  
Clay Concentration ◽  
Seagrass Ecosystems

Abstract. The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e. silt and clay), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between Corg and mud (i.e. silt and clay, particle sizes <63 μm) contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relative high soil Corg contents with relatively low mud contents (i.e. mud-Corg saturation) together with significant allochthonous inputs of terrestrial organic matter could overall disrupt the correlation expected between soil Corg and mud contents. This study shows that mud (i.e. silt and clay content) is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil Corg content for scaling up purposes when opportunistic and/or low biomass seagrass species (i.e. Zostera, Halodule and Halophila) are present (explaining 34 to 91% of variability), and in bare sediments (explaining 78% of the variability).

STUDIES WITH WASTE SULPHITE LIQUOR: II. WASTE SULPHITE LIQUOR AS A SOIL AGGREGATING AGENT

1959 ◽  
Vol 39 (2) ◽  
pp. 92-97 ◽  
Author(s):  
J. J. Doyle ◽  
A. A. MacLean
Keyword(s):  
Biological Activity ◽  
Organic Carbon ◽  
Carbon Content ◽  
Clay Content ◽  
Organic Carbon Content ◽  
Early Stages

Ammonium-base waste sulphite liquor (solids) (W.S.L.S.) was added to three soils and incubated for 7 weeks. Weekly measurements of organic carbon content and aggregation showed an increase in aggregation to a maximum at 3 weeks, followed by a decline and then by a second increase at 6 weeks. This increase and decline in aggregation paralleled very closely the corresponding biological activity as indicated by loss of organic carbon. Results suggest that decomposition of sugars is responsible for the⁁ development of aggregation in the early stages of incubation and that the ligninsulphonates may have an effect after further incubation.The aggregating effect of W.S.L.S. was compared with that of two synthetic conditioners HPAN and VAMA. The effect of all materials varied considerably with the clay content of the soil. Results indicate that W.S.L.S. is about 1/16 as effective as HPAN and about 1/36 as effective as VAMA.

A Comparative assessment of estimated soil hydraulic conductivity from rainfall simulator and infiltrometer using laboratory repacked soil samples

2021 ◽  
Author(s):  
Aparimita Priyadarshini Naik ◽  
Sreeja Pekkat
Keyword(s):  
Hydraulic Conductivity ◽  
Comparative Assessment ◽  
Evaluation Methodology ◽  
Soil Pressure ◽  
Rainfall Simulator ◽  
Near Surface ◽  
Mean Values ◽  
Soil Hydraulic Conductivity ◽  
Significant Difference ◽  
Soil Hydraulic

&lt;p&gt;Near surface soil hydraulic conductivity is an essential parameter for various hydrological, geotechnical, and environmental-related studies. Currently, many instruments are in practice for evaluating this parameter, both in field, and laboratory. The rainfall simulator (RS) and mini disc infiltrometer (MDI) are two instruments used for the indirect estimation of hydraulic conductivity by many researchers and engineers. However, both the devices differ in their working philosophy and evaluation methodology. While the RS works by considering large soil volumes and providing a positive soil pressure, the MDI works for small sampled volumes and supply negative boundary head. Therefore, the two devices can result in varying estimates of hydraulic conductivity. In this study, a comparative assessment is carried out between the saturated hydraulic conductivity (K&lt;sub&gt;s&lt;/sub&gt;) estimates from the two instruments using laboratory experiments for two different soil textures (loam and sand). The infiltration results from the RS are analyzed using the Green-Ampt method, and from the MDI is analyzed using the Zhang's method followed by the Kutilek and Nielson method to produce K&lt;sub&gt;s&lt;/sub&gt; values. The K&lt;sub&gt;s&lt;/sub&gt; results from both the instruments are compared with the values obtained using the laboratory falling-head permeameter test. A one-way ANOVA and the Fisher&amp;#8217;s Least Significant Difference (LSD) test as a posthoc test are carried out to analyze the statistical significance of the differences in the estimates of K&lt;sub&gt;s&lt;/sub&gt; by the two devices. The results showed that the two devices produced varying K&lt;sub&gt;s&lt;/sub&gt; results for both the soil textures, with the MDI mean values being one order higher than the RS mean. Compared with the permeameter values, the mean values from the RS were closer to the permeameter than the MDI. However, the ANOVA test and the Fisher&amp;#8217;s LSD test reported that the variations between the two devices with that of the permeameter were not significant for both the soil textures. On the other hand, the RS and MDI variations were reported significant by the ANOVA and post hoc test.&lt;/p&gt;

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