Showing papers in "Canadian Journal of Soil Science in 1966"
TL;DR: In this paper, acid ammonium oxalate extracts and in dithionite-citrate-bicarbonate extracts of a wide range of Canadian soils, several oxide and silicate minerals, and some amorphous preparations of iron or aluminum and silica.
Abstract: Iron and aluminum were determined in acid ammonium oxalate extracts and in dithionite–citrate–bicarbonate extracts of a wide range of Canadian soils, several oxide and silicate minerals, and some amorphous preparations of iron or aluminum and silica. The oxalate extraction dissolved much of the iron and aluminum from the amorphous materials but very little from crystalline oxides, whereas the dithionite extraction dissolved a large proportion of the crystalline iron oxides as well as much of the amorphous materials. Oxalate-extractable iron and aluminum gave a useful indication of Bf horizon development in many soils, even if the parent materials were high in iron oxides. In one class of Gleysolic soils, however, the Bfg horizons were high in dithionite-extractable iron and low in oxalate-extractable iron. An accumulation of goethite was found in the Bfg horizon of some of these soils. In some other Gleysolic soils iron was depleted in the A horizon but there was no horizon of iron accumulation. Extractio...
1,875 citations
TL;DR: In this paper, five soils were subjected to temperatures of 1° and −14 °C for three weeks and found that freezing caused a marked increase in the total amount of free amino acids extracted.
Abstract: Five soils were subjected to temperatures of 1° and −14 °C for 3 weeks. Freezing caused a marked increase in the total amount of free amino acids extracted. The amounts of free amino acids released were greater in soils where decomposition of organic matter was more complete. While prolonged storage of soil at 1 °C had no measurable effect on the free amino acids released, storage over a long period at −14 °C decreased the free amino acid content. Equilibration of wetted soil at room temperature prior to storage at cold temperatures decreased the extractable free amino acids. The data support the contention that part of the effect of soil freezing on the acceleration of microbial activity is due to release of available energy sources.
51 citations
TL;DR: The color of cultivated surface samples from Chernozemic and Gray Wooded soils were measured by visual and spectroreflectance methods as discussed by the authors, and the results showed that the color of these surface samples varied with the number of visitors.
Abstract: The color of cultivated surface samples from Chernozemic and Gray Wooded soils were measured by visual and spectroreflectance methods. Variations in visual color measurements among different observ...
50 citations
TL;DR: In a 7-year study of eight summerfallow treatments, the percentage of erodible soil (soil particles < 0.84mm in diameter) at the completion of tillage in the fall, and prior to preseeding tillage the following spring, was significantly influenced by the summer-fallow method as discussed by the authors.
Abstract: In a 7-year study of eight summerfallow treatments, the percentage of erodible soil (soil particles < 0.84 mm in diameter) at the completion of tillage in the fall, and prior to preseeding tillage the following spring, was significantly influenced by the summerfallow method. The Wood Mountain clay loam soil studied was significantly less erodible in the spring than it was the previous fall, indicating overwinter aggregation of the erodible fraction.
37 citations
TL;DR: In this paper, the authors evaluated several methods for providing an index of the availability of soil nitrogen by relating laboratory soil test values to yields of dry matter and uptake or nitrogen by orchardgrass in the greenhouse.
Abstract: Several methods for providing an index of the availability of soil nitrogen were evaluated by relating laboratory soil test values to yields of dry matter and uptake or nitrogen by orchardgrass in the greenhouse. Determination of soil organic matter or total soil nitrogen contents was relatively ineffective. Available nitrogen initially present in the soil at sampling time, extracted by several different methods, was superior to measurements of nitrogen released upon incubation. The nitrate form of nitrogen, either initially present or released upon incubation, served as a better index of soil nitrogen availability than the ammonium form. Inclusion of initial nitrates and nitrates released upon incubation as independent variables in a multiple regression resulted in the highest correlation with total nitrogen uptake. In the three incubation methods evaluated, discarding the initial nitrogen content of the soil, as is commonly done, severely reduced the validity of the tests as measures of nitrogen availab...
34 citations
TL;DR: In a greenhouse experiment, yields of Charlottetown 80 and Herta barley decreased with increasing rates of aluminum applied to a Caribou loam soil as mentioned in this paper, and the decline in yield was greater with the Herta v...
Abstract: In a greenhouse experiment, yields of Charlottetown 80 and Herta barley decreased with increasing rates of aluminum applied to a Caribou loam soil. The decline in yield was greater with the Herta v...
31 citations
TL;DR: In a laboratory and greenhouse investigation into the uptake of Cs-137 by oats and alfalfa, both the concentration and uptake were found to vary widely for a number of Canadian soils.
Abstract: In a laboratory and greenhouse investigation into the uptake of Cs-137 by oats and alfalfa, both the concentration and uptake of Cs-137 were found to vary widely for a number of Canadian soils. The Cs-137 concentration in oats were found to be related to the degree of fixation of Cs-137 by the soil and to the available K content of the soil in that plants grown on soils with high fixation of Cs-137 and high available K content were low in Cs-137, whereas plants grown on soils with low fixation of Cs-137 and low available K had a higher content of Cs-137. Although it was considered possible that plants could utilize non-exchangeable Cs-137, results obtained by an experiment using alfalfa as a test crop failed to prove this possibility. The time of application of CaCO3 or K relative to the time of application of Cs-137 was found to influence the uptake of Cs-137 by oats. When CaCO3was applied 1 month prior to the application of Cs-137, the uptake of Cs-137 was less than when the Cs-137 was applied 1 month p...
31 citations
TL;DR: In this paper, three distinctive types of banded fabrics related to the degree of eluviation were observed in the upper and lower portions of the Ae horizons of Saskatchewan soils.
Abstract: Three distinctive types of banded fabric related to the degree of eluviation were observed in Ae horizons of Saskatchewan soils. In addition, a type of intertextic fabric and cleavage block fabric were found to be characteristic of the upper and lower portions respectively of Ae horizons. Although essentially similar fabrics can occur within Ae horizons of Chernozemic, Solonetzic, Podzolic, and Gleysolic soils, the occurrence of specific fabric types appears to be related to the degree of eluviation which the horizons have undergone and bears a general relationship to the macrostructure exhibited by the soil.
30 citations
TL;DR: In this paper, soil samples taken from a Podzol Bh horizon were extracted with NaOH solutions, ranging in concentrations from 0.05 to 1.0 N.
Abstract: Soil samples taken from a Podzol Bh horizon were extracted with NaOH solutions, ranging in concentrations from 0.05 to 1.0 N. The highest proportions of soil C, N, Al2O3, Fe2O3, SiO2 K2O, and P2O5 were extracted by 0.1 and 0.15 N NaOH solutions.Following extraction, aliquots of each extract were passed over H-resin. The ash contents of purified extracts were as follows: 0.05 N NaOH = 27%; 0.1 N NaOH = 17%; 0.15 N NaOH = 13%; 0.25 N NaOH = 7%; 0.35 N NaOH and higher = < 5%. Repeated passage over H-resin of organic matter extracted by low base concentrations did not substantially lower the ash content. The most suitable extractant for obtaining organic matter preparations low in ash content was 0.4 or 0.5 N NaOH solution.
28 citations
TL;DR: The available boron content of the genetic horizons of eight Ontario soils was determined using a hot-water extraction and a sunflower test as mentioned in this paper, showing that the content in the horizons was generally higher than that in the C horizons.
Abstract: The available boron content of the genetic horizons of eight Ontario soils was determined using a hot-water extraction and a sunflower test. The available boron was highest in the surface horizons and decreased in the zones of eluviation to a level equal to or lower than that in the parent material. The content in the horizons was generally higher than that in the C horizons.The water-soluble boron was closely related to the organic matter content in a quadratic regression (R2 = 0.691). When pH and clay content were included in regressions, a positive organic matter × pH component was the single most important variable, explaining 64.4% of the variability. Additional terms involving clay content and pH did not greatly increase the R2 value.
24 citations
TL;DR: In this paper, the absorbance of a sodium pyrophosphate extract of each sample served as basis for grouping the samples into three broad classes: (i) peat, (ii) mucky peat - peaty muck, and (iii) muck.
Abstract: Carboxyls, phenolic and alcoholic hydroxyls, carbonyls, and methoxyls were determined in 20 organic soil samples that ranged from peats, mucky peats, peaty mucks to mucks. The absorbance of a sodium pyrophosphate extract of each sample served as basis for grouping the samples into three broad classes: (i) peat, (ii) mucky peat – peaty muck, and (iii) muck.A statistical analysis of the analytical data showed that (a) the determination of COOH and of OCH3 groups distinguished between the peat and muck classes, and (b) measurement of alcoholic OH groups differentiated between the peat class and the intermediate class and between the peat and muck classes. The experimental data indicated that increased humification was associated with increases in COOH, OCH3, and to a lesser extent of C==O groups, increased solubility in dilute sodium pyrophosphate solution, decreases in alcoholic OH groups but practically no changes in phenolic OH groups. It is suggested that functional group analysis could be used as a supp...
TL;DR: In this article, it was suggested that the role of the carbon tetrachloride was to release ammo acids from microbial or other cellular material in the soil, and that the amino acids extracted in the presence of carbon TTRC made up 0.1 to 1.0% of the total soil amino acids recovered after acid hydrolysis.
Abstract: The amount of water-soluble amino acids in the soils studied was low but qualitatively most of the common amino acids were found except cystine and methionine. Extracting the soil with water in the presence of carbon tetrachloride, or carbon tetrachloride containing a complexing agent, increased this amount 25 to 100 times. It is suggested that the role of the carbon tetrachloride was to release ammo acids from microbial or other cellular material in the soil. The complexing agent apparently had little effect on the amount of amino acids extracted with water. The amino acids extracted in the presence of carbon tetrachloride made up 0.1 to 1.0% of the total soil amino acids recovered after acid hydrolysis.
TL;DR: In this paper, profile samples from two fine-textured soils were analyzed for native fixed NH4, ammonium-fixing capacity, exchangeable K and organic matter content, and the decrease in NH4 fixation with proximity to the surface was due to potassium ion and organic content.
Abstract: Profile samples from two fine-textured soils were analyzed for native fixed NH4, ammonium-fixing capacity, exchangeable K, and organic matter content. Ammonium fixation decreased with proximity to the surface whereas exchangeable K and organic matter increased. Adding KCl to Sceptre subsoil to increase the exchangeable K decreased NH4 fixation approximately in proportion to the amount of KCl added. Destruction of organic matter prior to NH4 fixation increased the amount of NH4 fixed, the increase being greater the higher the organic matter content of the sample. The decrease in NH4 fixation with proximity to the surface was due to potassium ion and organic matter content.
TL;DR: In this article, the ammonia, hexosamine, and amino acid nitrogen fractions of soil hydrolyzates were determined with the Technicon autoanalyzer and the results compared with those from other more rapid methods of analysis.
Abstract: The ammonia, hexosamine, and amino acid nitrogen fractions of soil hydrolyzates were determined with the Technicon autoanalyzer and the results compared with those from other more rapid methods of analysis. Ammonia determination by steam distillation agreed well with that by the autoanalyzer. Amino acid nitrogen, as determined by direct color development with ninhydrin and as ammonia after ninhydrin oxidation, agreed well with total amino acid nitrogen. Steam distillation was not a very satisfactory method of determining hexosamine nitrogen, probably because it was determined by difference between total distillable and distillable ammonia and the hexosamine nitrogen was small relative to the total nitrogen distilled.The soils tested contained approximately 20% acid-insoluble nitrogen. The acid hydrolyzate contained approximately 36% of total soil nitrogen as amino acid nitrogen, about 22% as ammonia nitrogen, and about 4% as hexosamine nitrogen. Approximately 20% of the soil nitrogen appeared in the hydro...
TL;DR: In this article, the presence of bands in the lower sola has presented difficulties in the classification of soils developed from pitted deltaic sandy parent materials west of Edmonton, Alberta, and the bands were shown to contain more organic matter, free iron, and clay than the interbands, which resulted in a darker, redder color and finer texture as observed in the field.
Abstract: The presence of bands in the lower sola has presented difficulties in the classification of soils developed from pitted deltaic sandy parent materials west of Edmonton, Alberta. The bands were shown to contain more organic matter, free iron, and clay than the interbands, which resulted in a darker, redder color and finer texture as observed in the field. The bands were often coincidental with stratified layers, but their occasional transgression across geologic stratification and their development in profiles without stratification suggested a pedogenic origin. Micropedological investigations revealed oriented clay around the sand grains in the bands and not the interbands, further indicating that the increase in clay was due, at least in part, to illuviation.The bands in the soils investigated have sufficient total thickness of clay accumulation to meet the requirements for a Bt horizon and together with their chemical, physical, and mineralogical characteristics permit their inclusion in the Eluviated D...
TL;DR: In this article, it was shown that the protein content of spring wheat, grown in the growth chamber, could be effectively controlled by nitrogen supply and soil moisture stress, and that protein contents above 16% were obtained only where yields were below the maximum attainable.
Abstract: Experiments are reported in which it was shown that the protein content of spring wheat, grown in the growth chamber, could be effectively controlled by nitrogen supply and soil moisture stress. Protein contents above 16% were obtained only where yields were below the maximum attainable. In the protein range from 11 to 16%, it was possible to increase both protein and yields concurrently; protein contents higher than 16% were realized only where a growth factor such as moisture was below optimum for maximum yields.Moderate moisture stresses resulted in maximum efficiency of water use by the crop. High levels of nitrogen had more influence on the growth of straw than grain; the straw/grain ratio widened with increasing increments of nitrogen
TL;DR: In this article, the pH-dependent C.E.C values were determined with Ca(OAc)2'+'CaCl2 at pH 7 of the untreated soil and of the soils after H2O2 treatment, after extraction with acid ammonium oxalate, and after heating at 200 °C in an atmosphere of N2.
Abstract: A study was made of the pH-dependent C.E.C. as a means of characterizing and differentiating the B horizons of Brunisolic and Podzolic soils. The pH values were measured in 0.01 M CaCl2 after which the soils were extracted with Nacl to determine the percentage base saturation and sum of exchangeable cations. The total C.E.C. values were determined with Ca(OAc)2 + CaCl2 at pH 7 of the untreated soil and of the soils after H2O2 treatment, after extraction with acid ammonium oxalate, and after heating at 200 °C in an atmosphere of N2. The pH-dependent C.E.C. represented by the difference between the C.E.C value determined with Ca(OAc)2 + CaCl2 and the sum of cations extracted with NaCl was found to be small for the B horizons of Brown Forest and Brown Wooded soils. The B horizons of Podzol, Humic Podzol, Acid Brown Wooded, Concretionary Brown, and some Acid Brown Forest soils had high pH-dependent C.E.C. The horizons with high pH-dependent C.E.C. contained significant quantities of amorphous sesquioxide–orga...
TL;DR: In this article, young seedlings of flax and cereals, grown in a greenhouse, were subjected to 0, 12.5, and 25.0 cm of soil moisture tension for periods of 7, 14, and 21 days.
Abstract: Young seedlings of flax and cereals, grown in a greenhouse, were subjected to 0, 12.5, and 25.0 cm of soil moisture tension for periods of 7, 14, and 21 days The grain, straw, and root yields of all plant species, except barky, increased with increasing soil moisture content was maintained near field capacity during the growth of plants. The yields of oats, winter wheat, and fall rye decreased with increasing duration of flooding, whereas those of barley, flax and spring wheat were variable. Correlation coefficients between yields of tops and roots were positive.
TL;DR: The potential buffering capacity (PBCK) as mentioned in this paper showed some relation to the amount of non-exchangeable K which was an important source of K in most of the soils.
Abstract: Equilibration of 11 soils in 0.002 M CaCl2 containing different amounts of KCl gave activity ratios which showed a higher degree of correlation with the portion of K-uptake derived from the exchangeable form than with the total K-uptake by plants. The values together with estimates of the quantities of K released (−ΔK°) as obtained from equilibration curves were found to be much more indicative of the total K-uptake than were the values only.The ratio , or potential buffering capacity (PBCK), showed some relation to the amount of non-exchangeable K which was an important source of K in most of the soils. The PBCK values were correlated with the clay content of the soils and the degree of K-fixation.
TL;DR: The relationship of the mean weight diameter of water-stable aggregates to certain soil properties (clay, organic matter, free iron, free aluminum, and polysaccharide contents) and the relationship of increase in aggregation caused by VAMA to the same properties of 24 New Brunswick soils were evaluated by correlation and regression analyses as mentioned in this paper.
Abstract: The relationship of the mean weight diameter of water-stable aggregates to certain soil properties (clay, organic matter, free iron, free aluminum, and polysaccharide contents) and the relationship of the increase in aggregation caused by VAMA to the same properties of 24 New Brunswick soils were evaluated by correlation and regression analyses.Simple correlation coefficients relating aggregation to soil properties indicated that organic matter (r = 0.627), polysaccharides (r = 0.602), and aluminum (r = 0.679) were the most important factors. However, when the influence of each factor was separated by partial correlation, the coefficients were not significant. On the other hand, the combined effects of all factors as indicated by the multiple correlation coefficient (r = 0.743) was significant at the 1% level. The effect of the same soil properties on response to VAMA, as shown by increase in mean weight diameter, indicated that clay exerted the greatest influence. The relationship with other factors was ...
TL;DR: In this paper, experiments were started in 1945 to study the effectiveness of various rates of monoammonium phosphate and barnyard manure for wheat production on an Indian Head clay Chernozem.
Abstract: Experiments were started in 1945 to study the effectiveness of various rates of monoammonium phosphate and barnyard manure for wheat production on an Indian Head clay Chernozem. The yield data indicate that the various long-term treatments have changed the relative yield potential of their respective plots. Over the years, the responses of wheat to the various treatments have changed, with the higher rates of amendments giving progressively higher yield increases while the lower rates have given less significant yield increases. Soil tests and 'A' value data from subplots show that the plots which had high rates of amendments have phosphorus values much higher than the plots which received no amendments. The use of moderate rates of monoammonium phosphate for the past 20 years has maintained the phosphorus fertility of the Indian Head soil near an optimum level.
TL;DR: In this article, the lime potential, corrected for the varying magnitude of the ionic product (Al) (OH)3, and the degree of base saturation based on the cations extracted with NaCl from acid Ah and Ap horizons of mineral soils and from surface samples of mucks and peats, agreed closely with the curve calculated for the titration of Al bentonite with Ca(OH)2.
Abstract: Values of the lime potential, corrected for the varying magnitude of the ionic product (Al) (OH)3, and the degree of base saturation based on the cations extracted with NaCl from acid Ah and Ap horizons of mineral soils and from surface samples of mucks and peats, agreed closely with the curve calculated for the titration of Al bentonite with Ca(OH)2. The peat and muck samples, although strongly acid, had percent base saturation values over 88% owing to the low values of the ionic product (Al) (OH)3 in the aqueous extracts of these organic soils.
TL;DR: In recent field trials nitrogen-phosphorus fertilizer increased the yield of wheat following summerfallow on a Chernozemic clay soil cropped previously for 50 years in a summer-fallow, wheat, wheat rotation.
Abstract: In recent field trials nitrogen–phosphorus fertilizer increased the yield of wheat following summerfallow on a Chernozemic clay soil cropped previously for 50 years in a summerfallow, wheat, wheat rotation. But the fertilizer had no significant effect on wheat yield when the previous cropping system during the 50-year period was summerfallow, wheat, oats, brome–alfalfa for3 years, intertilled corn, wheat, and oats. The beneficial effect of brome–alfalfa in the rotation was reflected in a higher yield of wheat. The average yield of grain per year in the recent trials was 400 kg/ha higher when brome–alfalfa had been included in the rotation.The brome–alfalfa crops produced a better physical condition in the soil. Furthermore, soil samples from the rotation containing brome–alfalfa had higher contents of nitrogen, organic carbon, and total phosphorus than did the samples from the summerfallow, wheat, wheat rotation.
TL;DR: In a series of experiments designed to describe Cs fixation and release by soils and sou separates, considerable Cs-137 was found to be fixed by the sand fractions of agricultural soils.
Abstract: In a series of experiments designed to describe Cs fixation and release by soils and sou separates, considerable Cs-137 was found to be fixed by the sand fractions of agricultural soils. The amount fixed by the sand exceeded that fixed by the clay m calcium-saturated samples taken from Podzolic soils. Cesium fixed when added as CsCl in macroconcentrations (5 meq per 100-g sample) was greater in the clay fractions than the sand fractions for all soils. These findings support the findings of others that there is more than one site for CS fixation depending on the concentration. Considerable Cs-137 was released by soil separates when shaken in the presence of H-resin. The amount released by the sand fraction was substantially greater than that released by the clay fraction for two of the three soils investigated. The fixation of Cs-137 was found to be approximately proportional to applied dose over a large range of carrier-free Cs-137 concentrations. The amount fixed by soils of alkaline pH was higher than t...
TL;DR: The average non-exchangeable K, Mg, and Ca contents of the clay fractions were considerably higher in the neritic and littoral sediments than the corresponding contents of floodplain sediments as mentioned in this paper.
Abstract: Mineralogical and chemical analyses were conducted on samples representing Fraser River sediments deposited under freshwater and seawater environments. The analyses indicated these sediments to be highly detrital in nature, dominantly reflecting their source area and being influenced to a lesser degree by marine diagenesis. Indications of diagenesis were most pronounced in sediments from the neritic environment. These were characterized by a reduction in the content of expanding-lattice minerals. The average non-exchangeable K, Mg, and Ca contents of the clay fractions were considerably higher in the neritic and littoral sediments than the corresponding contents of the floodplain sediments.The type of alluvial deposit—lateral accretion, vertical accretion, or deltaic deposition—appeared to have little influence on their clay mineral contents.
TL;DR: Ammonium applied alone or after addition of K depressed the uptake of K by oats grown in a sandy loam soil in the greenhouse as discussed by the authors, when NH4 was added first and K later at seeding.
Abstract: Ammonium applied alone or after addition of K depressed the uptake of K by oats grown in a sandy loam soil in the greenhouse. When NH4 was added first and K later at seeding, however, NH4 increased...
TL;DR: In this article, the distribution constant for exchange of calcium and magnesium ions was determined in Wyoming bentonite suspensions with pH values varying from 3.5 to 9.2, using a neutral salt to extract the exchangeable cations.
Abstract: The distribution constant for exchange of calcium and magnesium ions was determined in Wyoming bentonite suspensions with pH values varying from 3.5 to 9.2. Using a neutral salt to extract the exchangeable cations, the mean value of the distribution constant using ion activities in solution was found to be 1.06 and there was no significant difference in the constant at different pH values. Thus, the presence of Al ions in the acid preparations, the precipitation of hydroxy aluminum polymers on the clay surfaces at intermediate pH values, and the precipitation of excess base in the alkaline region possibly as double hydroxides of Al and Mg or Ca had no significant effect on the exchange distribution of Mg and Ca ions.Under comparable conditions, the ion product (Al) (OH)3 had the same value in the presence of Ca or Mg. Because of this and the fact that the distribution constant for exchange was approximately 1, the two ions may be considered as a single ionic species for practical purposes in suspensions o...
TL;DR: In this paper, boron absorption by sunflowers in the greenhouse from samples of the genetic horizons of eight Ontario soils increased with increasing water-soluble Boron content (R2 ǫ = 0.78).
Abstract: The boron absorption by sunflowers in the greenhouse from samples of the genetic horizons of eight Ontario soils increased with increasing water-soluble boron content (R2 = 0.78). The absorption from a group of 17 cultivated surface samples was also positively correlated with water-soluble boron (R2 = 0.54).Clay content had the greatest influence on boron absorption after the influence of water-soluble boron was removed. The two variables in a multiple curvilinear regression accounted for 79% of the variability in absorption from the cultivated surface samples. The absorption increased with increasing clay content up to 15% and then decreased with a further increase in clay up to 20%. Organic matter content had a lesser effect on absorption. The -atm moisture value had a relatively large influence on absorption from the profile samples, but essentially no influence on that from the surface samples. The pH and CaCO3 content had very little influence on absorption from either set of samples.
TL;DR: In this paper, chemical, physical, and mineralogical studies have been made on Gray Wooded and Solonetzic soils developed on varved clays in four glacial lacustrine basins in north central British Columbia.
Abstract: Chemical, physical, and mineralogical studies have been made on Gray Wooded and Solonetzic soils developed on varved clays in four glacial lacustrine basins in north central British Columbia.The soils have a high content of exchangeable cations. Calcium and magnesium are the dominant cations in all soils but sodium is higher in Solonetzic man in dray Wooded soils.The data suggest that clay has been translocated from the A into the Bt horizons of all soils. The ratio of clay in the B horizon to that in the A horizons is apparently related to the size of the clay fraction, its mineralogical composition, the nature of the exchangeable cations, and the intensity of leaching. Clay eluviation appears to have been most marked in Solonetzic soils containing montmorillonoid minerals in the fine clay fraction.Within each depositional basin, mineralogical composition of the clay fraction is relatively uniform: greater differences were found between basins. Mineralogical composition is thought to reflect the source o...
TL;DR: In this paper, the authors used average measurements of the frequency of occurrence and of the maximum and minimum depths of horizon variations to describe and compare these variations in soils and grouped them into five variability classes that serve as guidelines with which field data can be compared.
Abstract: Irregular tonguing horizons and those that occur sporadically in soil sections are not only difficult to describe consistently but also pose problems in correlating and classifying soil series. Average measurements of the frequency of occurrence and of the maximum and minimum depths of horizon variations can be used to describe and compare these variations in soils. Theoretical values of these parameters are combined and grouped into five variability classes that serve as guidelines with which actual field data can be compared.