Loss involved by igniting soil fractions during the mechanical analysis of soils

1928 ◽  
Vol 18 (1) ◽  
pp. 123-130
Author(s):  
F. J. Martin
Keyword(s):  
Organic Matter ◽  
Clay Fraction ◽  
Tropical Soils ◽  
Mechanical Analysis ◽  
Lateritic Soils ◽  
Soil Fractions ◽  
Silica Alumina ◽  
Silica Alumina Ratio

1. Examinations have been made of the losses involved by igniting fractions of tropical soils.2. It has been found that these losses are partly due to organic matter and partly to combined water; the greater part of the loss is due to water.3. In the clay fraction there is a correlation between the amount of combined water and the silica/alumina ratio; the greater the ratio the less the combined water. This is affected by the proportion of iron present.4. Lateritic soils lose more water on ignition than other soils but the lateritic material in soils is not necessarily evenly distributed throughout the fractions; those fractions containing the highest proportions of lateritic material lose the most water.

Laterite and lateritic soils in Sierra Leone

1927 ◽  
Vol 17 (4) ◽  
pp. 530-547 ◽  
Author(s):  
F. J. Martin ◽  
H. C. Doyne
Keyword(s):  
Sierra Leone ◽  
Clay Fraction ◽  
Lateritic Soils ◽  
Silica Alumina ◽  
Silica Alumina Ratio

(1) The formation of laterite and lateritic soils in Sierra Leone has been studied and the mode of formation and the composition of these soils is described.(2) It is suggested that since the clay fraction is regarded as the most important fraction in determining the reactions of a soil the classification of laterite and lateritic soils should be based on an examination of the clay fraction. It is further suggested that where the silica/alumina ratio in the clay fraction falls below 2·0 the soil should be described as “lateritic,” and where this ratio falls below 1·33 the soil should be described as laterite.

scholarly journals Nature of Aggregation in Two Tropical Soils of Puerto Rico

1969 ◽  
Vol 52 (3) ◽  
pp. 227-232
Author(s):  
Raul Pérez Escolar ◽  
M. A. Lugo López
Keyword(s):  
Organic Matter ◽  
Puerto Rico ◽  
Organic Matter Content ◽  
Tropical Soils ◽  
Mechanical Analysis ◽  
Matter Content ◽  
Clay Particles ◽  
General Data ◽  
The Tropics ◽  
Cementing Agent

In both Catalina clay and Cialitos clay there are no marked differences in the properties of the different-sized aggregates and the corresponding whole soils studied. Although well-drained upland soils in the Tropics are supposed to contain less organic matter than those in the cooler Temperate Zones, the organic-matter content of Catalina clay and Cialitos clay was as great as that found in many soils of the same texture in Temperate Zones. Organic matter has a very definite influence as a cementing agent between clay particles. This was shown by the low clay values obtained when or ganic matter was not removed by pretreating the soil with hydrogen per oxide prior to mechanical analysis. From the general data obtained in the study of the aggregates of both soils, it can be inferred that they are formed largely as a result of the breakdown of large massive units of soils. If synthesis occurred to a larger extent, more marked differences could be expected in their constitutional makeup.

scholarly journals The suspended matter of sea water

1950 ◽  
Vol 29 (1) ◽  
pp. 139-143 ◽  
Author(s):  
F. A. J. Armstrong ◽  
W. R. G. Atkins
Keyword(s):  
Organic Matter ◽  
Calcium Carbonate ◽  
Ferric Oxide ◽  
Suspended Matter ◽  
Water Mass ◽  
Sea Water ◽  
Dry Weight ◽  
Insoluble Organic Matter ◽  
Silica Alumina ◽  
Silica Alumina Ratio

Sea water collected at Station E1, surface, between June 1948, and November 1949, contained suspended matter from 2·77 to 0·45 g./m.3 (or parts per million) dried and ignited. A few determinations of insoluble organic matter gave 1·77 to 1·15 parts per million dry weight at 100° C. The ignited residue contained from 55 to 17% silica, 28 to 3 of ferric oxide, 20 to under 1 of alumina and 70 (or excluding one high value 29) to 9 calcium carbonate. There was nothing in the records for temperature or salinity to suggest that the water mass had changed during the period of sampling.The analyses reveal an unsuspectedly large amount of iron, compared with that found in solution. The ignited residue is rich in silicate, judging from the silica alumina ratio, but it is quite doubtful whether the additional supply of silicate available for diatoms is at all adequate to balance their requirements calculated on a phosphate utilization basis. It seems more probable that a considerable amount of the phosphate is available for non-siliceous phytoplankton.

scholarly journals DISTRIBUTION OF ORGANIC CARBON IN DIFFERENT SOIL FRACTIONS IN ECOSYSTEMS OF CENTRAL AMAZONIA

2015 ◽  
Vol 39 (1) ◽  
pp. 232-242 ◽  
Author(s):  
Jean Dalmo de Oliveira Marques ◽  
Flávio Jesus Luizão ◽  
Wenceslau Geraldes Teixeira ◽  
Max Sarrazin ◽  
Sávio José Filgueira Ferreira ◽  
...  
Keyword(s):  
Organic Matter ◽  
Clay Fraction ◽  
Particle Size Analysis ◽  
Light Fraction ◽  
Size Analysis ◽  
Primary Forest ◽  
Organic C ◽  
Soil C ◽  
Soil Fractions ◽  
C Stocks

Organic matter plays an important role in many soil properties, and for that reason it is necessary to identify management systems which maintain or increase its concentrations. The aim of the present study was to determine the quality and quantity of organic C in different compartments of the soil fraction in different Amazonian ecosystems. The soil organic matter (FSOM) was fractionated and soil C stocks were estimated in primary forest (PF), pasture (P), secondary succession (SS) and an agroforestry system (AFS). Samples were collected at the depths 0-5, 5-10, 10-20, 20-40, 40-60, 60-80, 80-100, 100-160, and 160-200 cm. Densimetric and particle size analysis methods were used for FSOM, obtaining the following fractions: FLF (free light fraction), IALF (intra-aggregate light fraction), F-sand (sand fraction), F-clay (clay fraction) and F-silt (silt fraction). The 0-5 cm layer contains 60 % of soil C, which is associated with the FLF. The F-clay was responsible for 70 % of C retained in the 0-200 cm depth. There was a 12.7 g kg-1 C gain in the FLF from PF to SS, and a 4.4 g kg-1 C gain from PF to AFS, showing that SS and AFS areas recover soil organic C, constituting feasible C-recovery alternatives for degraded and intensively farmed soils in Amazonia. The greatest total stocks of carbon in soil fractions were, in decreasing order: (101.3 Mg ha-1 of C - AFS) > (98.4 Mg ha-1 of C - FP) > (92.9 Mg ha-1 of C - SS) > (64.0 Mg ha-1 of C - P). The forms of land use in the Amazon influence C distribution in soil fractions, resulting in short- or long-term changes.

Effects of climate change on soil organic matter chemical composition and carbon content in different physical fractions

2021 ◽  
Author(s):  
Moritz Mohrlok ◽  
Victoria Martin ◽  
Alberto Canarini ◽  
Wolfgang Wanek ◽  
Michael Bahn ◽  
...  
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Soil C ◽  
Size Classes ◽  
Soil Fractions ◽  
Total Soil ◽  
C And N ◽  
Amp Clay

<p>Soil organic matter (SOM) is composed of many pools with different properties (e.g. turnover times) which are generally used in biogeochemical models to predict carbon (C) dynamics. Physical fractionation methods are applied to isolate soil fractions that correspond to these pools. This allows the characterisation of chemical composition and C content of these fractions. There is still a lack of knowledge on how these individual fractions are affected by different climate change drivers, and therefore the fate of SOM remains elusive. We sampled soils from a multifactorial climate change experiment in a managed grassland in Austria four years after starting the experiment to investigate the response of SOM in physical soil fractions to temperature (eT: ambient and elevated by +3°C), atmospheric CO<sub>2</sub>-concentration (eCO<sub>2</sub>: ambient and elevated by +300 ppm) and to a future climate treatment (eT x eCO<sub>2</sub>: +3°C and + 300 ppm). A combination of slaking and wet sieving was used to obtain three size classes: macro-aggregates (maA, > 250 µm), micro-aggregates (miA, 63 µm – 250 µm) and free silt & clay (sc, < 63 µm). In both maA and miA, four different physical OM fractions were then isolated by density fractionation (using sodium polytungstate of ρ = 1.6 g*cm<sup>-3</sup>, ultrasonication and sieving): Free POM (fPOM), intra-aggregate POM (iPOM), silt & clay associated OM (SCaOM) and sand-associated OM (SaOM). We measured C and N contents and isotopic composition by EA-IRMS in all fractions and size classes and used a Pyrolysis-GC/MS approach to assess their chemical composition. For eCO<sub>2</sub> and eT x eCO<sub>2 </sub>plots, an isotope mixing-model was used to calculate the proportion of recent C derived from the elevated CO<sub>2 </sub>treatment. Total soil C and N did not significantly change with treatments.  eCO<sub>2</sub> decreased the relative proportion of maA-mineral-associated C and increased C in fPOM and iPOM. About 20% of bulk soil C was represented by the recent C derived from the CO<sub>2</sub> fumigation treatment. This significantly differed between size classes and density fractions (p < 0.001), which indicates inherent differences in OM age and turnover. Warming reduced the amount of new C incorporated into size classes. We found that each size class and fraction possessed a unique chemical fingerprint, but this was not significantly changed by the treatments. Overall, our results show that while climate change effects on total soil C were not significant after 4 years, soil fractions showed specific effects. Chemical composition differed significantly between size classes and fractions but was unaffected by simulated climate change. This highlights the importance to separate SOM into differing pools, while including changes to the molecular composition might not be necessary for improving model predictions.    </p>

Temperature effects on organic matter and microbial biomass dynamics in temperate and tropical soils

1998 ◽  
Vol 30 (10-11) ◽  
pp. 1309-1315 ◽  
Author(s):  
B. Grisi ◽  
C. Grace ◽  
P.C. Brookes ◽  
A. Benedetti ◽  
M.T. Dell'abate
Keyword(s):  
Organic Matter ◽  
Microbial Biomass ◽  
Temperature Effects ◽  
Tropical Soils ◽  
Biomass Dynamics

scholarly journals The status of phosphorus and other fertility parameters in soils of Puerto Rico

1969 ◽  
Vol 90 (3-4) ◽  
pp. 145-157 ◽  
Author(s):  
David Sotomayor-Ramírez ◽  
Gustavo A. Martínez
Keyword(s):  
Organic Matter ◽  
Puerto Rico ◽  
Soil Fertility ◽  
Temporal Dynamics ◽  
Organic Matter Content ◽  
Tropical Soils ◽  
Matter Content ◽  
Soil Test ◽  
Commercial Laboratory ◽  
Soil Fertility Status

There is a need to quantitatively assess the soil fertility status of tropical soils. Descriptive summaries help describe the effectiveness of liming programs, nutritional limitation in soils and the relative risk of off-field nutrient transport. A database of 1,168 soil test results collected from 1989 to 1999 from nearly 400 cultivated farms in Puerto Rico was used. Samples were analyzed for pH, organic matter (Walkley-Black method), extractable phosphorus (P) (Olsen and Bray 1), and exchangeable bases (NH4Oac method) by a commercial laboratory. Thirty-six percent of the samples had acidity problems (pH <5.5). Twenty-three percent of the samples had low organic matter content (<20 g/kg), and 16% had high category (>40 g/kg) values. Fifty-three and 56% of the samples showed a need to fertilize with magnesium (Mg) and potassium (K), respectively, because they had values below the suggested critical levels of 2.5 cmolc/kg for soil exchangeable Mg and of 0.4 cmolc/kg for K. On the basis of current soil fertility criteria, P fertilization would be required in 69% of the samples with pH less than 7.3, but only in 28% of the samples with pH greater than or equal to 7.3. Although the soils grouped with pH >7.3 had a greater proportion of samples in the "extremely high" soil test P category, the potential environmental impact may be lessened because the climatic and topographic conditions where these soils occur favor less runoff. Follow-up studies are needed to assess the spatial variability and the temporal dynamics of the nutritional status of soils of Puerto Rico. 

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