Showing papers in "Soil Science in 1977"
TL;DR: In this article, data from the Rothamsted classical field experiments on the effects of long-continued cropping and manuring on the amount of organic matter in soil, on the age of this soil organic matter, and on the number of microbial biomass in the soil.
Abstract: Data are assembled from the Rothamsted classical field experiments on the effects of long-continued cropping and manuring on the amount of organic matter in soil, on the age of this soil organic matter, on the amount of microbial biomass in the soil, and on the rate at which plant residues d
1,157 citations
TL;DR: In this article, the mass size distributions of airborne particles generated by wind erosion of two soils, one coarse-grained and one finegrained, show two distinct modes in each, the coarser mode, between 10 and 100 μm equivalent radius, is due to the presence in the parent soil of loose erodible particles.
Abstract: Mass size distributions of airborne particles generated by wind erosion of two soils, one coarse-grained and one fine-grained, show two distinct modes in each. The coarser mode, between 10 and 100 μm equivalent radius, is due to the presence in the parent soil of loose erodible particles whi
191 citations
TL;DR: In this paper, the authors studied the phosphate sorption characteristics of soil material from selected soil profiles of West Africa and found that the concentration of Phosphate in soil solutions was almost invariably low in comparison with the requirements for
Abstract: Phosphate sorption characteristics of soil material from selected soil profiles of West Africa were studied. These soils represent a wide range of parent materials and agroclimatic conditions. Phosphate concentration in soil solutions was almost invariably low in comparison with the requirements for
176 citations
TL;DR: In this paper, the binding of divalent metal ions by humic acid was examined by a modified potentiometric titration procedure involving sequential additions of metal ion to solutions of the Humic acid at constant pH.
Abstract: The nature of the binding of divalent metal ions by humic acid was examined by a modified potentiometric titration procedure involving sequential additions of metal ion to solutions of the humic acid at constant pH. At pH values below the point of oxide hydrate formation, the drop in pH resulted fro
162 citations
TL;DR: In this article, it was shown that the majority of the salt in Antarctic soils is derived from marine salt, although there are significant contributions from chemical weathering processes, and that the chemistry of the salts clearly shows that chemical wading takes place in Antarctic soil, even in the coldest and most arid regions of the Trans-Antarctic Mountains.
Abstract: One of the prominent features of Antarctic soils, and one which shows their relationship with soils in other arid regions of the world, is the high content of soluble salts. These salts consist largely of the sulphates, chlorides, and nitrates of sodium, potassium, magnesium, and calcium. Almost all of the possible crystalline phases that may be formed by combination of these anions and cations are found. The origin of the salts has been a matter of controversy for many years. Various origins have been postulated, including chemical weathering of rocks, deposition of marine salts, and leaching from sedimentary rocks. Soils sampled along the length of the Trans-Antarctic Mountains during the last 17 years have formed from a wide range of soil parent materials, under significantly different climatic conditions and age of weathering surface. From the relationship between these factors and the nature of the salts found in the soils, soil pH, and the distribution of calcite crusts, it is possible to show that the greater part of the salt is derived from marine salts, although there are significant contributions from chemical weathering processes. The chemistry of the salts clearly shows that chemical weathering takes place in Antarctic soils, even in the coldest and most arid regions of the Trans-Antarctic Mountains.
155 citations
TL;DR: In this paper, a study was made on the adsorption of phenolic acids, which are known to be plant growth inhibitors, by kaolinite, illite, vermiculite, noncrystalline hydroxy-Al and -Fe compounds, and four Taiwan soils.
Abstract: A study was made on the adsorption of phenolic acids, which are known to be plant growth inhibitors, by kaolinite, illite, vermiculite, noncrystalline hydroxy-Al and -Fe compounds, and four Taiwan soils. The adsorption sequence of phenolic acids by kaolinite, illite, and vermiculite followed
155 citations
TL;DR: In this article, tension lysimeters were used to monitor continuously the soil solution from the O/sub 2/, a2, iib2hir, and ivb32 of a podzol (cryandept) in the Central Cascades, Washington.
Abstract: Tension lysimeters were used to monitor continuously the soil solution from the O/sub 2/, a2, iib2hir, and ivb32 of a podzol (cryandept) in the Central Cascades, Washington. Precipitation, forest throughfall, and stream water were also collected. Averages of three years of data show a drop in pH as the meteoric water passes through the canopy and the forest floor. Solutions leaving the iib2hir show an increase in pH; a further increase occurs in the ivb32 and the stream. There is an increase in the summation of the major cations (Ca, Mg, K, and Na) and electrical conductivity as the precipitation penetrates the canopy; a further increase occurs as the solutions pass the forest floor. A lowering of these parameters is recorded in the solutions leaving the iib2hir. Below the iib2hir, the concentrations of the cations, the electrical conductivity, and the pH increases. The concentrations of the major rock-forming elements, Si, Al, and Fe, are low in the precipitation. In the soil, soluble Si is the most abundant at any level, and Fe is the least. Al has intermediate values. In general, the three elements have a minimal level after passing the iib2hir, but they increase below it. Total N decreasesmore » from the precipitation to the iib2hir, where a minimum value is obtained; it increases below. Total P follows a similar trend. Mobile fulvic acids, seen to arise in the 0 horizons, are reduced by 60 percent to 70 percent within the iib2hir. According to these data, the iib2hir delineates the lower boundary of the biopedological compartment that starts at the top of the canopy. The geochemical compartment starts below the iib2hir and includes the ivb32 and bedrock material in contact with groundwater. The presence of these compartments points to the invalidity of the use of stream and groundwater data to delineate the biopediological sector of a forest ecosystem.« less
116 citations
TL;DR: In this paper, the root may increase the soil solution concentration of sparingly soluble nutrients by absorbing it from low concentration in the soil, but the root uptake is limited by diffusion.
Abstract: The rate of uptake of a nutrient may be limited by its rate of diffusion through the soil or by the ability of the root to absorb it from low concentration in the soil solution. In the growth-response range of concentration, uptake of N, P, and K appears to be limited by diffusion. Transpiration rate, in these conditions, should have little influence. The root may be able to increase the soil solution concentration of sparingly soluble nutrients.
114 citations
TL;DR: In this article, the effects of pH, reaction time, chemical reduction and irradiation on electron spin resonance (ESR) parameters were evaluated on powders and solutions of fulvic acid (FA) and on a number of different molecular-weight fractions separated from it.
Abstract: Electron spin resonance (ESR) parameters (free radical concentrations, g-values and line widths) were determined on powders and solutions of fulvic acid (FA) and on a number of different molecular-weight fractions separated from it. Major objectives were to evaluate effects of pH, reaction time, chemical reduction and irradiation on the ESR parameters and to obtain information on the identity of the free radicals. Two types of free radicals were detected in all FA-preparations: (a) permanent ones, having long life spans; and (b) transient ones, with relatively short lives, which were generated in large concentrations by different treatments in the following order of decreasing efficiencies: chemical reduction > irradiation > raising the pH. Spectroscopic splitting factors (g-values) of permanent and transient radicals were similar, indicating that the radicals had similar structures. From the magnitude of the g-values it was likely that the radicals were substituted semiquinones which, in alkaline solutions, were stabilized as semiquinone ions. In most cases, the treatments that generated transient radicals were reversible. While the permanent free radicals were stabilized by the FA-structure, the transient ones were not. Reasons for this behavior remain to be uncovered. The generation from FA of large concentrations of transient free radicals by chemical reduction and irradiation should be of interest to soil scientists in that it might have a number of practical applications.
104 citations
103 citations
TL;DR: In this article, the main effects of Cd and Pb interactions on corn plants were investigated in a greenhouse experiment with 24 and 31 days following emergence from pots containing Bloomfield loamy sand.
Abstract: In a greenhouse experiment corn plants were harvested 24 and 31 days following emergence from pots containing Bloomfield loamy sand. The soil CEC was 2.3 meq/100 g. It had 140 kg/ha of P, and 220 kg/ha of 1N neutral ammonium acetate extractable K. Calcium, Mg, K, and P concentrations in plant tissue were determined. Treatment combinations were a factorial arrangement of 0, 2.5, and 5 ..mu..g/g of Cd and 0, 125, and 250 ..mu..g/g of Pb. At 24 days following emergence, there were significant main effects of Cd and Pb upon the Ca, Mg, K, and P concentration in corn plants. The Cd linear x Pb linear interaction significantly (..cap alpha.. = .05) affected P concentration and uptake of each element. At 31 days following emergence, Cd and Pb main effects influenced the Ca, Mg, and K status of the plant, but had no significant effect upon P content. At this stage of development, there were three significant Cd-Pb interactions that affected nutrient concentration and four interactions that affected nutrient uptake. Results observed in this study suggest that the statistical significance of various effects depends upon stage of development of the corn plant, and that certain Cd-Pb interactions influenced nutrientmore » concentration in the plant. 20 references, 4 tables.« less
TL;DR: In this paper, the effect of suspension pH on Zn solubility was quantitatively evaluated by plotting the negative log Zn in solution (pZn) against pH.
Abstract: Four acid soils from Hawaii and three calcareous soils from Pakistan were used to study the effect of suspension pH on Zn solubility. The soils, at different pH values, were equilibrated with added Zn for 6 days at 25°C. After equilibration, Zn concentrations in the supernatants were determined by atomic absorption spectrophotometry. The effect of suspension pH was quantitatively evaluated by plotting the negative log Zn in solution (pZn) against pH. A linear relationship was observed up to pH 7.0 for acid soils. As the system passed neutrality, a general increase was noted in the amounts of Zn in solutions for the soils high in organic matter. The increase in Zn solubility over the alkaline range was assumed to be due to dispersion of organic matter, which either released complexed Zn or provided chelating agents for added Zn and reduced adsorption or precipitation. For the calcareous soils, the relationship between Zn solubility and pH was nonlinear. It was assumed that at higher pH, Zn in solutions precipitated as Zn(OH)2, ZnCO3, or Ca-zincate. There was no indication of colloidal peptization or formation of soluble zincate ions with NaOH.
TL;DR: When the amount of inorganic phosphate (P) sorbed by contrasting subsoils was expressed as a fraction of the overall Langmuir sorption maximum for that soil, the sorption data plotted on essentially the same isotherm as mentioned in this paper.
Abstract: When the amount of inorganic phosphate (P) sorbed by contrasting subsoils was expressed as a fraction of the overall Langmuir sorption maximum for that soil, the sorption data plotted on essentially the same isotherm. This reflected the similarity in the Langmuir sorption constants relating
Abstract: Disinfection, sterilization, and preservation , Disinfection, sterilization, and preservation , کتابخانه دیجیتال جندی شاپور اهواز
TL;DR: The role of naturally-occurring soil organic matter (SOM) in the translocation of metal ions from parent materials to biological systems is discussed in this article, where a hypothesis or model is proposed wherein their translocation includes a sequence of reactions.
Abstract: The role of naturally-occurring soil organic matter (SOM) in the translocation of metal ions from parent materials to biological systems is discussed. To explain the movement of essential elements, a hypothesis or model is proposed wherein their translocation includes a sequence of reactions
TL;DR: In this article, a rating scale was developed to quantitatively evaluate several important morphological properties of soils, such as relative distinctness of horizons and relative development of a soil profile.
Abstract: A rating scale was developed to quantitatively evaluate several important morphological properties of soils. The rating scale was used in the following two ways: 1) to determine the relative distinctness of horizons and 2) to determine the relative development of a soil profile. The determination of relative distinctness of horizons was made by a comparison of adjacent horizons, while the determination of the relative profile development was made by a comparison of the C horizon to the horizons above it in the profile. The rating scale was effective in evaluating pedological development of soils developed in a humid-temperate climate. Additional morphological factors may be needed to evaluate pedological development of soils developed in other climatic regimes.
TL;DR: In this paper, the effect of growing rice for the reclamation of sodic soils was examined in a pot experiment and it was found that rice increased the percolation rate even in the highly sodic soil.
Abstract: The favourable effect of growing rice for the reclamation of sodic soils was examined in a pot experiment Rice increased the percolation rate even in the highly sodic soil This seems due to the physical presence of roots which facilitate the movement of water along its surfaces However, the reclamation efficiency per unit amount of water did not increase, because the water moved mainly through the macropores and not through the entire mass Biological activity of rice roots lowered the soil pH and decreased the loss of organic matter during the process of leaching Rice plants resulted in high cumulative removal of soil exchangeable sodium caused by mobilisation of native insoluble CaCo3 as a result of increased hydrolysis and CO2 liberated by plant roots In sodic soils as well as in a Na-resin-sand-CaCO3 system it was observed that the reclaiming effect of rice was more biochemical in nature rather than through increased permeability alone
TL;DR: In this paper, an experimental technique was devised to measure the maximum binding ability (MBA) of any macromolecule having electron donor groups, which is a dialysis technique where polymer portions are isolated in dialysis bags and equilibrated with metal-ion solutions of increasing concentrations.
Abstract: An experimental technique was devised to measure the maximum binding ability (MBA) of any macromolecule having electron donor groups. It is a dialysis technique wherein polymer portions are isolated in dialysis bags and equilibrated with metal-ion solutions of increasing concentrations. The excess of free metal ions is removed by repeated changes of distilled water. The device proposed allows one to run 12 or more samples simultaneously. By this procedure the amount of metal ions attached to the macromolecules as a function of the metal-ion concentration of the equilibrium solution is measured. Plotting the amount of metal bound to 1 mg of the polymer vs. free-metal concentration at equilibrium gives Langmuir isotherm-like curves. Therefore, to calculate MBA the linear Langmuir plot is applied. The limitation and applicability of the Langmuir isotherm is discussed. The Ca(II), Mg(II), Cu(II), and Zn(II) MBA of microbial humic acid-like polymers synthesized by Stachybotrys atra, Hendersonula toruloidea, and Eurotium echinulatum, model phenolic polymers synthesized by autoxidative and enzymatic reactions, extracted soil and peat humic acids, Hansenula holstii polysaccharde and karaya gum were determined. For the majority of the polymers, the MBA sequence with the metal ions tested was: Cu > Ca > Mg > Zn. This conforms with Ahrland's concepts of class A and B electron-acceptors and Pearson's concepts of hard and soft acids and bases considering that the majority of the active sites on the polymers contain O as donor atom (COOH and phenolic OH) and the minority contain N, S, and probably P as electron donors. With all the metals the sequence of MBA for all the microbial polymers was: E. echinolatum > H. toruloidea > S. atra > H. Holstii polysaccharide. The MBA of the model phenolic polymers were similar to the fungus humic acid-type polymers. The maximum binding ability of Cu for all the humic acid-type polymers varied from 0.29 to 2.26 atom-micrograms per mg of polymer. The data obtained support the hypothesis that the microbial ecology of soil may markedly influence the MBA characteristics of the naturally occurring SOM and, therefore, it may also strongly influence the metal translocation in soils and the availability of essential elements to biological systems.
TL;DR: In this paper, a theoretical development is presented that describes water retention in soils underlain by a coarse-textured stratum, and incorporates the physical characteristics of the overlying soil, the depth to the coarse layer, and the coarseness of the underlay.
Abstract: A theoretical development is presented that describes water retention in soils underlain by a coarse-textured stratum, and incorporates the physical characteristics of the overlying soil, the depth to the coarse layer, and the coarseness of the underlay. Field data are presented for the Manawatu fine sandy loam, a soil with a coarse layer at 90 cm. For this soil the layering resulted in an additional 5.5 cm of water storage at field capacity, an increase of 31 percent over a similar hypothetical soil with the coarse stratum absent.
TL;DR: The Andosols of the Taranaki region of New Zealand are formed from andesitic parent materials derived from the late Quarternary stratovolcano, Mt. Egmont.
Abstract: The Andosols of the Taranaki region of New Zealand are formed from andesitic parent materials derived from the late Quarternary stratovolcano, Mt. Egmont. Numerous pathways exist in the evolution of Taranaki Andosols. The principal volcanic events that have dominated soil evolution in this region are outlined and an ordering of stages in Andosol genesis is presented. An estimate of the weathering of soil parent materials, from major silicate analyses of lapilli horizons, suggests the half-life of andesitic glass in Taranaki is about 7,000 years.
TL;DR: In this paper, the authors considered the hydrodynamic dispersion of tracer which occurs under the combined influence of molecular diffusion and convection when a fluid flows through a finite column of porous material.
Abstract: This study considers some aspects of the hydrodynamic dispersion of tracer which occurs under the combined influence of molecular diffusion and convection when a fluid flows through a finite column of porous material. In particular, the study discusses (1) the use of the principle of superposition to obtain breakthrough curves for pulsed and periodic inputs of tracer, (2) the form of dispersion coefficients in terms of dimensionless groups of parameters, and (3) the mechanism underlying dispersion. (13 refs.)
TL;DR: In this paper, sulfate solutions were mixed with a soil that had a high capacity to adsorb sulfate, and three techniques were used to see whether the strength of the link between sulfate and the soil particles increased with time.
Abstract: Sulfate solutions were mixed with a soil that had a high capacity to adsorb sulfate, and three techniques were used to see whether the strength of the link between sulfate and the soil particles increased with time. The techniques were measurements: of the change in sulfate concentration in the soil solution; of the change in availability to plants; and of desorption of sulfate. All three techniques showed that there were, indeed, slow changes. These were similar to, but much slower than, those observed for phosphate, molybdate, and fluoride. This suggests that such behavior is a characteristic of specifically adsorbed anions, not just of phosphate.
TL;DR: In this article, a new technique for extracting potential phytotoxic materials from soils is presented and discussed, which features the use of water and a chelating agent (Na2EDTA at pH 7.5) as the primary levers of extraction.
Abstract: A new technique for extracting potential phytotoxic materials from soils is presented and discussed. This technique features the use of water and a chelating agent (Na2EDTA at pH 7.5) as the primary levers of extraction, and, therefore, avoids the use of denaturing alkaline conditions. Stres
TL;DR: In this article, the masses of total organic carbon in the whole soil samples and in the fractions, together with their /sup 14/C content and /sup 13/C/sup 12/C ratios, were also determined.
Abstract: Soil organic matter was extracted using the classical procedure and fractionated into humin (nonextractable), humic acid, and fulvic acid. The masses of total organic carbon in the whole soil samples and in the fractions, together with their /sup 14/C content and /sup 13/C//sup 12/C ratios, were also determined. The following New Zealand soils were studied: a Fluvaquent, with experimental pasture plots, formed from deeply mixing subsoils of low organic carbon content; a Typic Fragiaqualf and a Typic Dystrochrept with moderately productive pastures; and an Umbric Vitrandept at two sites under native tussock and under introduced grasses of low productivity. The degree of radiocarbon enrichment of the different fractions in both topsoil and subsoil samples was examined in relation to differences in soil type, soil biological activity, and vegetation history. There was variation in the distribution and enrichment of the organic matter fractions both within the same soil type and between soil types, as well as between the topsoil and subsoil of the same soil. Differences appeared to be primarily a function of the stage of decomposition and translocation of the fractions through the soil rather than due to vegetation differences.
TL;DR: Sodium fluoride was incubated with soils for periods of up to 100 days and at temperatures that ranged from 3° to 80°C, and the results were analogous to those obtained on the same soils with phosphate and molybdate as mentioned in this paper.
Abstract: Sodium fluoride was incubated with soils for periods of up to 100 days and at temperatures that ranged from 3° to 80°C. With increasing period and temperature of incubation there were decreases in both the concentration of fluoride in the soil solution and in the fluoride that could be desorbed in a given period. It was concluded that this was due to an increase in the firmness of the link between fluoride and the surface of the soil particles. This increase also changed the adsorption characteristics of the soil, making it less able to adsorb further fluoride and less able to adsorb phosphate.
The results were analogous to those obtained on the same soils with phosphate and molybdate. This indicates that the increase with time in the strength of the bond between phosphate or molybdate and the soil cannot be entirely explained by postulating that it is due to forming a second link to the surface through a second oxygen atom.
TL;DR: A numerical model of soil water dynamics was devised to simulate infiltration, drainage, evaporation, and water storage in texturally layered profiles as mentioned in this paper, which consisted of sandlike, loamlike, and clay-like soil of known hydraulic properties.
Abstract: A numerical model of soil water dynamics was devised to simulate infiltration, drainage, evaporation, and water storage in texturally layered profiles. The layers consisted of sandlike, loamlike, and claylike soil of known hydraulic properties. Data presented on the flow patterns of the variously st
TL;DR: In this article, the principle of hard soft acids and bases, HSAB, which can predict stable complex formation, is reviewed and compared to complex formation in the soil system, and demonstrated by comparing the softness valves to observed cation exchange selectivity in soils, that the majority of soil exchange materials behave as relatively soft bases.
Abstract: The principle of hard soft acids and bases, HSAB, which can predict stable complex formation, is reviewed. In the soil system, cation exchange selectivity can be compared to complex formation, which can then be described in terms of HSAB theory. It is then demonstrated by comparing “softness” valves to observed cation exchange selectivity in soils, that the majority of soil exchange materials behave as relatively soft bases.