Showing papers in "Soil Science in 1978"
498 citations
TL;DR: In this paper, the nature, transformations and relative sizes of the organic P pools for five North American grassland regions were investigated, showing that a high percentage of the P in grassland soils is organic.
Abstract: A high percentage of the P in grassland soils is organic. Where the NaHCO3- extractable P is below the adequate level, plants must rely on mineralization of organic P. This paper attempts to show the nature, transformations, and relative sizes of the organic P pools for five North American grassland
413 citations
TL;DR: The NaHCO3 method of Olsen et al. as discussed by the authors was primarily designed to extract inorganic P (P1) and to correlate this P-pool with plant response.
Abstract: The sodium-bicarbonate (NaHCO3) method of Olsen et al. was primarily designed to extract inorganic P (P1) and to correlate this P-pool with plant response. This procedure was used to follow the transformations of organic P (P0) substrates in soil. Various commercial P0 substrates were added to a san
288 citations
TL;DR: In this article, a study was conducted to determine the distribution of phosphomonoesterases (acid and alkaline phosphatases) in soil and showed that the activities of these enzymes were associated with surface soils and that they decrease with depth acid phosphatase was p
Abstract: Several phosphatases are present in soils This study was conducted to determine the distribution of phosphomonoesterases (acid and alkaline phosphatases) Results showed that the activities of these enzymes were associated with surface soils and that they decrease with depth Acid phosphatase was p
155 citations
TL;DR: In this paper, the surface tensions of the following solutions were measured: (a) fulvic acid (FA) and humic acid (HA) at various pH and concentration levels; (b) FAs and HAs from widely differing origins; (c) pyrolyzed FA; (d) leaf extracts; and (e) saturated soil extracts.
Abstract: Surface tensions of the following solutions were measured: (a) fulvic acid (FA) and humic acid (HA) at various pH and concentration levels; (b) FAs and HAs from widely differing origins; (c) pyrolyzed FA; (d) leaf extracts; and (e) saturated soil extracts.Both FA and HA solutions lowered the surface
150 citations
124 citations
TL;DR: In this article, the molecular weight of the major fraction of the soluble organic compounds, designated as the mobile fulvic acid fraction, was determined to be in the range of 837-845 by gel filtration.
Abstract: The mobile organic compounds present in the soil solutions of a subalpine Podzol were studied. The molecular weight of the major fraction of the soluble organic compounds, designated as the mobile fulvic acid fraction, was determined to be in the range of 837–845 by gel filtration. Infrared analysis of these organic compounds indicated the presence of aromatic hydroxy carboxylic acids. There was a sharp decrease in the mobile fulvic acid fraction as the soil solutions passed through the IIB2hir and IIB2ir horizons. Those organics remaining in solution showed the presence of strongly chelated acid groups. Laboratory studies indicated that the IIB2ir horizon was highly effective in adsorption of the soluble organic compounds present in the soil solutions, while the IIB2hir was not. The removal of the organic compounds from the soil solution was due to the presence of reactive sesquioxides within the IIB2ir horizon. This suggests that the IIB2hir horizon is growing downward into the IIB2ir horizon. The results confirm earlier work on the importance of the B2hir horizon in delineating two distinct chemical compartments of a Podzol.
121 citations
TL;DR: In this paper, the mechanisms of bonding of Mn2+, Cu2+, and VO2+ in humic acid extracted from a mineral soil were investigated by electron spin resonance spectroscopy.
Abstract: The mechanisms of bonding of Mn2+, Cu2+, and VO2+ in humic acid extracted from a mineral soil were investigated by electron spin resonance spectroscopy. The Mn(H2O)62+ ion appeared to retain its inner hydration sphere upon adsorption, and was adsorbed at the organic surface by electrostatic attraction. Both Cu2+ and VO2+ entered into rigid surface complexes with oxygen ligands of organic functional groups, however, losing rotational mobility. The different bonding mechanisms of these transition metal ions are explained in terms of ligand field effects. No evidence of highly covalent metal-organic bonds was found.
115 citations
TL;DR: In this paper, the relation of potentially mineralizable soil nitrogen, No, to the oxidative release of NH4-N from soil organic matter during extraction with acid KMnO4 was investigated, using 62 soils.
Abstract: The relation of potentially mineralizable soil nitrogen, No, to the oxidative release of NH4-N from soil organic matter during extraction with acid KMnO4 was investigated, using 62 soils. Included in the study were members of 8 soil orders comprising 43 noncalcareous and 19 calcareous soils. Soils w
111 citations
TL;DR: The Mecanique des sols Reference Record was created on 2004-09-07, modified on 2016-08-08 as mentioned in this paper, and is used for the Elements finis reference record.
Abstract: Keywords: Elements finis ; Mecanique des sols Reference Record created on 2004-09-07, modified on 2016-08-08
TL;DR: A solution of phenolic compounds was added separately to montmorillonite, illite, and kaolinite, each of which had been mixed with quartz in a 3:7 ratio, and to pure quartz.
Abstract: A solution of phenolic compounds was added separately to montmorillonite, illite, and kaolinite, each of which had been mixed with quartz in a 3:7 ratio, and to pure quartz. The oxidative polymerization took place at once and was allowed to proceed for 10 days. The humic and fulvic acids wer
TL;DR: In this article, a new technique based on the combined use of potentiometric titration and ion-selective electrodes is proposed for determining apparent stability constants (successive stability constants and overall stability constants) of divalent metal cation (Cu/sup 2 +/, Pb/sup2 +/, and Cd/sup 1 +/) complexes with humic acids.
Abstract: A new technique based on the combined use of potentiometric titration and ion-selective electrodes is proposed for determining apparent stability constants (successive stability constants and overall stability constants) of divalent metal cation (Cu/sup 2 +/, Pb/sup 2 +/, and Cd/sup 2 +/) complexes with humic acids. Fourteen humic acids from diverse sources, including humified rice straw, were examined. The stability constants increased with an increase in pH, and the order of values obtained was Cu/sup 2 +/ greater than Pb/sup 2 +/ much greater than Cd/sup 2 +/. The overall logarithmic stability constants with the soil humic acid examined were 8.65 for Cu/sup 2 +/, 8.35 for Pb/sup 2 +/, and 6.25 for Cd/sup 2 +/ at pH 5.0. The overall stability constants of Cd/sup 2 +/ complexes ranged from 4.3 x 10/sup 5/ to 4.6 x 10/sup 7/ at pH 6.0. The overall stability constants increased with increasing humification in the higher humification range, and the values correspond to the contents of very weakly acidic functional groups. The binding mechanisms of the metal cation complexes with humic acids seemed to accompany the coordinate bonds of undissociated very weakly acidic functional groups, in addition to the ionic bonds through COOH more » and/or OH groups. « less
TL;DR: In this paper, the authors have isolated biogenic opal from 15 taxa of the family Pinaceae and found that the opal contents varied from 0.08 percent of dry weight in Pinus resinosa to 1.37 percent in Larix decidua.
Abstract: Biogenic opal was isolated in measurable quantities from 15 taxa of the family Pinaceae. Opal contents varied from 0.08 percent of dry weight in Pinus resinosa to 1.37 percent in Larix decidua. The silica content of a widely ranging species, Tsuga canadensis, varied significantly with collection location in New York State, but the causes of variation were not investigated. All cell types in Pinaceae leaves may become weakly silicified, resulting in cellular fragments upon digestion, or heavily silicified, resulting in well-preserved cellular replicas. Epidermal phytoliths formed in intersto-matal files are the most common cellular particles in the wet ash silica residue. Vascular cells (both tracheary elements and transfusion parenchyma), fibers, asterosclerids, mesophyll cells, and endodermal cells were also represented in the ash of some species. Differences in the opal residue from different genera were observed, with endodermal polyhedrons limited to Picea, asterosclereids exclusive to Pseudotsuga, and epidermal cells with distinctly undulating margins present in Pinus, Tsuga, and Abies. Marginal undulations on the epidermal cells of Picea, Larix, and Pseudotsuga are less pronounced. Opal from Pinaceae leaves may be most readily separated from that of other plant materials by the presence of transfusion tissue tracheids with bordered pit impressions and tapering ends. Epidermal cells are also distinctive, although careful study will be required to differentiate them from the epidermal long cells and costal rods of grasses. Other particles may also be utilized in areas where the diversity of previous vegetative occupants has been limited.
TL;DR: In this paper, the authors examined soil samples from field plots under long-term management systems using standard plate count procedures and found a mean value for bacteria plus actinomycetes of 7 × 107/g soil.
Abstract: Soil samples from field plots under long-term management systems were examined using standard plate count procedures. Samples collected at monthly intervals from the different plots showed a mean value for bacteria plus actinomycetes of 7 × 107/g soil. The mean for fungi was 4 × 105/g soil.
TL;DR: In this article, it was shown that specific and nonspecific adsorption of Zn by Al 2O3 and Fe2O3 may be at least partially responsible for the frequently reported fixation and unavailability of added Zn to soils.
Abstract: Adsorption of Zn from aqueous solutions of ZnCl2 by hydrated Al2O3 and Fe2O3 was highly pH-dependent and increased markedly with increasing pH. Fe2O3 had a higher Zn adsorption capacity, at equivalent pH values, than Al2O3. Hydrogen ions were released upon adsorption of Zn2+ on the surface of Al2O3 and Fe2O3, suggesting that surface aquo (-OH2) and hydroxo (-OH) groups were involved in Zn adsorption. The molar ratio of H+ released to Zn2+ adsorbed onto Fe2O3 increased from 1.53 to 1.96 as suspension pH increased from 5.93 to 6.96, whereas the molar ratio of adsorbed Cl- to adsorbed Zn2+. Similiar results were obtained for Al1O3. It was postulated that two types of adsorption, specific and nonspecific, depending upon reversibility (exchangeeability with Ba2+, occured. Specific adsorption involved adsorption of Zn2+ and release of two H+ions for each mole of Zn2+ adsorbed and accounted for 60 to 90 percent of total Zn adsorption by Fe2O3. An olation bridge structure between Zn2+ and two surface -OH2 groups was postulated. Nonspecfic adsorption of Zn accounted for 40 to 10 percent of the total Zn adsorption, and was thought to involve adsorption of ZnCl+ or Zn2+ plus Cl- and the release of one H+ion for each mole ov Zn2+ adsorbed. A single-bond structure in which ZnCl+ replaced one H+ from surface -OH2 groups was postulated. The raio of specific to nonspecific adsorption increased with increasing pH. It was concluded that specific adsorption of Zn by Al2O3 and Fe2O3 may be at least partially responsible for the frequently responsible for the frequently reported fixation and unavailability of added Zn to soils.
TL;DR: In this article, the tracers were injected into soil 4.5 cm from onion root surfaces at rates designed to label available pools of Ca and 32P at equivalent specific activities.
Abstract: Calcium-45 and 32P were injected into soil 4.5 cm from onion root surfaces at rates designed to label available pools of Ca and P at equivalent specific activities. Both tracers were detected in mycorrhizal but not anonmycorrhizal plants after 5 days. Calcium-45 was detected less frequently and in m
TL;DR: In this article, the authors discuss properties and processes of forest soils and their properties in terms of properties, processes, and processes in the context of forest soil properties and process. ǫ
Abstract: Forest soils: properties and processes , Forest soils: properties and processes , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
TL;DR: In this article, the physical and chemical properties and the clay mineralogy of Normal and Light-Colored Andosols from Kitakami, Japan were studied, and the profiles of both AndoSols had features reflecting the repeated falls of tephras with different ages.
Abstract: Physical and chemical properties and the clay mineralogy of Normal and Light-Colored Andosols from Kitakami, Japan were studied. The profiles of both Andosols had features reflecting the repeated falls of tephras with different ages.The Normal Andosol, which is a common Andosol in Japan, sho
TL;DR: In this paper, the measured water pressure at different depths in a soil core and the weights during evaporation at the top of the core are calculated using a polynom.
Abstract: The moisture characteristic and the unsaturated hydraulic conductivity are calculated from the measured water pressures at different depths in a soil core and the weights during evaporation at the top of the core. The measured water pressure is assumed to represent the mean pressure in a layer of a certain thickness, and the moisture characteristic is assumed to be described with sufficient accuracy by a polynom. The tangent of the polynom in each pressure interval is solved from a set of equations. Assuming the hydraulic conductivity-water pressure relationship can be described by an exponential relationship with varying constants in the different pressure ranges, the constants can be solved from measured water pressure at two depths and three sequential moments, and the rate of change in water content below some defined depth in the core during two sequential time periods. Up to ten cores can be handled at the same time. Measuring at a core can be started and stopped at any time. The water pressure at different depths is measured with one pressure transducer, connected with a scannivalve; the weight is measured with a straingauge load cell; and the data are recorded on a magnetic cassette tape. The recorded data are processed by a computer and stored on a magnetic disc. If the saturated conductivity is relatively high, a steady-state infiltration method is applied to determine the unsaturated hydraulic conductivity at high water contents.
TL;DR: In this article, a generalized form of the Clausius-Clapeyron equation is derived for the equation of thermodynamic equilibrium between ice and water in porous media, which accounts for a difference between the pressure of the ice phase and the total potential (in pressure units) of the water phase.
Abstract: A derivation is given for the equation of thermodynamic equilibrium between ice and water in porous media. The equation accounts for a difference between the pressure of the ice phase and the total potential (in pressure units) of the water phase. Emphasis is laid on the distinction between the total potential and the hydrostatic pressure and osmotic pressure of the unfrozen soil solution. The difference between the hydrostatic pressure of the solution and the ice pressure is accounted for by the ice-water interfacial tension, as expressed by the generalized form of Laplace's equation. The resulting generalized form of the Clausius-Clapeyron equation is an equilibrium expression, whereas the Laplace equation only expresses a definition, valid under any circumstances. It is emphasized that all influences of the pore wall, which may or may not work via the diffuse double layer, and which cause the liquid to have lower Gibbs free energy than the equilibrium liquid at the same temperature, are collected in the osmotic pressure term.
TL;DR: In this paper, the authors presented simple linear models for estimating mean annual, seasonal, and monthly soil temperatures with reasonable accuracy, using only air temperature data, using simple, linear models.
Abstract: Though soil temperature is important to a variety of earth science subdisciplines, data are collected at few locations. This report presents simple, linear models for estimating mean annual, seasonal, and monthly soil temperatures with reasonable accuracy, using only air temperature data. A general equation based on all months and all sample stations taken together, seasonal equations, and equations for individual stations are provided. These models can be used to estimate soil temperature from air temperature data collected by the National Weather Service at stations throughout the United States.
TL;DR: In this paper, the relation of potentially mineralizable soil nitrogen, No to hydrolytic and oxidative release of NH4-N from soil organic matter by extraction with alkaline permanganate was investigated using 62 soils representing several major agricultural regions in the United States.
Abstract: The relation of potentially mineralizable soil nitrogen, No to hydrolytic and oxidative release of NH4-N from soil organic matter by extraction with alkaline permanganate was investigated using 62 soils representing several major agricultural regions in the United States. The NH4-N was recovered by steam-distilling 1-g samples of soil during extraction of 4 min with several concentrations of NaOH and KMnO4 in different combinations. The same concentrations of NaOH and KMnO4, were used to determine amounts of NH4-N released by hydrolysis (B) during steam distillation. Oxidative release was estimated as the difference between total NH4-N produced during alkaline permanganate extraction (BOx) and that derived by NaOH distillation. These NH4-N fractions were determined using inital NaOH concentrations ranging from 0.25 to 0.625 N, alone or with amounts of KMnO4 ranging from 0.032 to 0.5 g/10 ml of extractant. For all combinations of NaOH and KMnO4, the correlation coefficients relating B and BOx consistently were high (r = > 0.9). Correlations between the independent variables B and (BOx - B), ranged from r = 0.17 to 0.90. Multiple regressions of No on B and BOx were associated with coefficients of multiple correlation, R, that were relatively constant (generally, 0.8 to 0.9), despite the diversity of reagent concentrations used for extraction. THese and other considerations indicate that the NH4-N released by NaOH hydrolysis (B) and by KMnO4 oxidation (BOx - B) was derived, in large part, from the same soil organic sources (e.g., amides, amines, amino acids, and amino sugars). With few exceptions, correlations of No with BOx were as good as, or better than, simple correlations of No with B or (BOx - B). Thus, the extra effort required for separate NaOH and NaOH-KMnO4 extractions would not appear to be justified. The alkaline permanganate methods thus far reported by various investigators, as well as modifications evaluated in this study, offer a less precise and reliable basis for predicting No than does acid permanganate extraction for measuring oxidative release of NH4-N.
TL;DR: In this article, the internal drainage technique, which employs a neutron moisture meter and tensiometers, was used to evaluate the spatial variability of soil water properties of a 0.34 and 91.6-ha field.
Abstract: Soil water management requires a reliable estimate of soil water properties in order to predict and control the dynamics of water in a field soil. This estimate should take cognizance of the spatial variability of the soil water properties in the field. The internal drainage technique, which employs a neutron moisture meter and tensiometers, was used to evaluate the spatial variability of soil water properties of a 0.34 and 91.6-ha field. Five infiltration plots were established on each field. The precision with which the soil hydraulic conductivity K, as a function of moisture content α, could be obtained for a single soil type in the field was also determined. High variability in soil physical properties, such as percent gravel, sand, silt, and clay, and bulk density, resulted in a high variability in soil water retention characteristics and hydraulic conductivity. The coefficients of variability of these soil properties were only slightly higher for the 91.6-ha farm area than for the 0.34-ha area, consisting of one soil type on a nearly level topography. Although the spatial variability of soil water content was relatively low at any time and any depth after cessation of infiltration, ranging from 2.48 to 12.06 percent, the hydraulic conductivity values were far more divergent, having coefficients ranging from 47.6 to 146.9 percent. Steady-state moisture content and hydraulic conductivity were normally and log-normally distributed, respectively. Agreement between the plots of K versus α for the two drainage periods in 1975 and 1976 were generally satisfactory. The magnitude of soil water flux at any depth was predicted with some success, using a simple prediction equation that requires a knowledge of saturated hydraulic conductivity and the slope of the K(α) curve near saturation. The result was not expected, in view of the large coefficients of variability of soil water flux among the five plots on a soil.
TL;DR: In this article, water retention curves were measured on cores taken from five sites at six depths in a Bainsville clay loam soil and the measured K functions were steeper than those predicted, and the match between them was considered reasonable only at lower water contents.
Abstract: Soil water retention curves were measured on cores taken from five sites at six depths in a Bainsville clay loam soil. There were differences in both the shape and magnitude of the average moisture characteristic curves from one location to another in the 225m2 plot. Coefficients of variation ranged from 4.2 to 13 percent in the surface layers and from 2.4 to 6.5 percent in the deeper layers. There were no consistent trends in variability with respect to tensions from 0 to −500 cm H2O. Predicted and measured hydraulic conductivity functions were variable, often showing a 100-fold difference at a given water content. The measured K functions were steeper than those predicted, and the match between them was considered reasonable only at the lower water contents.
TL;DR: The rate and magnitude of the oxidation of thiosulfate (S2O3−) and elemental sulfur (S°) to sulfate, by two heterotrophic soil bacteria and Thiobacillus thiooxidans was compared in liquid medium and soil as mentioned in this paper.
Abstract: The rate and magnitude of the oxidation of thiosulfate (S2O3−) and elemental sulfur (S°) to sulfate, by two heterotrophic soil bacteria and Thiobacillus thiooxidans was compared in liquid medium and soil. The two heterotrophic organisms, Isolate 2, which oxidized S2O3− and Isolate 5, which oxidized S°, produced measurable and significant amounts of SO4− in liquid media and autoclaved soil.
Optimum heterotrophic oxidation occurred in autoclaved soil when the inoculated organisms were provided with an organic source of carbon as glucose. Conversely, glucose inhibited oxidation by T. thiooxidans, most likely via a build up of pyruvate. Under optimum conditions in autoclaved soil the rate and magnitude of heterotrophic oxidation were similar.
TL;DR: In this paper, a study was undertaken to determine selenium toxicity and the effect of phosphorus application on wheat (Triticum aestivum) in a greenhouse using sandy soil.
Abstract: A study was undertaken to determine selenium toxicity and the effect of phosphorus application on selenium in wheat (Triticum aestivum). Selenium in a compound was applied at 0, 2.5, 5, and 10 ppm to wheat in a greenhouse using sandy soil. Phosphorus in a compound was applied at 0, 50, and 100 ppm to the experimental plants. Sunflower (Helianthus annuus) was grown after wheat to determine the residual effect of selenium and phosphorus. Results indicated that high amounts (2.5 ppm and above) of added and residual selenium in soil decreased the growth of wheat and sunflower, decreased the absorption of zinc, copper, iron, manganese, sulfur, and nitrogen, and decreased the synthesis of nucleic acids, chlorophyll, and protein. The application of phosphorus decreased the harmful effects of selenium and increased all the above parameters. (3 graphs, 21 references, 4 tables)