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Showing papers in "Soil Science in 1996"


Journal ArticleDOI
TL;DR: It has been speculated that arbuscular mycorrhizal fungi produce extracellular compounds and that these are involved in soil stabilization and it was hypothesized that the hyphal protein could be found in soil.
Abstract: It has been speculated that arbuscular mycorrhizal fungi (AMF) produce extracellular compounds and that these are involved in soil stabilization. An unusual and abundant protein was found on hyphae of AMF, and it was hypothesized that the hyphal protein could be found in soil. The purpose of this

850 citations


Journal ArticleDOI
TL;DR: More than 30 years have passed since the first application of nuclear magnetic resonance (NMR) spectroscopy to soil organic matter (SOM), and there has been an explosion of applications using 1H, 13C, 31P, and 15N NMR on both solution and solid-state samples as discussed by the authors.
Abstract: More than 30 years have passed since the first application of nuclear magnetic resonance (NMR) spectroscopy to soil organic matter (SOM). Since then, there has been an explosion of applications using 1H, 13C, 31P, and 15N NMR on both solution and solid-state samples. These have greatly enhanced our

493 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of extractants on phosphorus determination by 31 P NMR spectroscopy was examined using five forest floor samples using five extractants: 0.25 M NaOH, 1.6 soil to Chelex in water, 1:6 soil-to-Chelex in NaOH and 1:1 mix of 0.5 M Naoh and O.1 M EDTA.
Abstract: The effect of extractants on phosphorus determination by 31 P NMR spectroscopy was examined using five forest floor samples. The extractants used were: 0.25 M NaOH, 1:6 soil to Chelex in water, 1:6 soil to Chelex in 0.25 M NaOH, and a 1:1 mix of 0.5 M NaOH and O.1 M EDTA. The broadest peaks were produced by the NaOH + EDTA extraction. However, NaOH + EDTA extracts contained the highest percentage of total phosphorus and the greatest diversity of P forms. These extracts were the only ones to show peaks for polyphosphates. Metals analysis indicated that NaOH + EDTA maintained Mn in solution, which seemed to be responsible for the line broadening. The sharpest peaks, with the best separation, were produced with Chelex + NaOH, and these were improved further by increasing the pH with NaOH prior to NMR analysis. Chelex + NaOH extracted 23 to 35% of the total soil P, Chelex in water extracted 10 to 13%, NaOH alone extracted 22 to 34%, and NaOH + EDTA extracted 71 to 90%. This work suggests that, because the extractant used will affect the P forms, care must be taken when interpreting studies of P cycling in soils using 31 P NMR spectroscopy and when comparing studies using different extractants.

364 citations


Journal ArticleDOI
TL;DR: In this paper, the bonding structures of arsenite and arsenate on goethite were studied by Transmission-Fourier Transform Infrared (T-FTIR) and Attenuated Total ReflectanceFTIR spectroscopy.
Abstract: The bonding structures of arsenite (As(III)) and arsenate (As(V)) on goethite (α-FeOOH) were studied by Transmission-Fourier Transform Infrared (T-FTIR) and Attenuated Total Reflectance-FTIR (ATR-FTIR) spectroscopy. ATR-FTIR spectra of deuterated goethite showed three bands of OD stretch, correspond

331 citations


Journal ArticleDOI

307 citations


Journal ArticleDOI
TL;DR: In this article, two independent factors -solvented organic chelators and preferential flow paths -enhanced metal mobility through soil, and the results indicated that previous laboratory metal leaching studies performed on homogenous soils might have greatly underestimated metal mobility in the field and that preferential flow, both alone and in combination with organic-facilitated transport, can accelerate metal leachability through soils.
Abstract: When sewage sludge is applied to land for disposal or intended beneficial use, heavy metals accumulate in the soil. Because of environmental concerns, many studies have been undertaken in an attempt to clarify the different factors that contribute to metal solubility, plant uptake, and leachability. This study attempted to determine if two independent factors - soluble organic chelators and preferential flow paths - enhance metal mobility through soil. Dilute solutions containing CdCl{sub 2}, ZnCl{sub 2}, CuCl{sub 2}, and Pb(NO{sub 3}){sub 2} were applied to soil columns with a rainmaker, and leachate metals and chloride concentrations were measured. For four columns, the input metal concentrations (mg L{sup {minus}1}) were 7.25 Cd, 4.55 Zn, 3.51 Cu, and 13.85 Pb. In other four other columns, the solution also contained dissolved organic matter so that the metals were organically complexed, and input metal concentrations (mg L{sup {minus}1}) were 6.30 Cd, 4.11 Zn, 3.19 Cu, and 12.55 Pb. For each treatment, two soil columns were undisturbed and two were constructed from homogenized soils. The continuous solution application rate was approximately 3 cm/day. The undisturbed soil columns treated with organically complexed metals had peak effluent concentrations of 30, 26, 28, and 27% for Cd, Zn, Cu,more » and Pb, respectively. Peak effluent concentrations for undisturbed columns treated with metals in water were 30 and 23% of influent concentrations for Cd and Zn, but only 15 and 12% for Cu and Pb, respectively. However, the four homogenized soil columns retained all added metals, whether the metals were added in water or as organic complexes. The results indicate that previous laboratory metal leaching studies performed on homogenous soils might have greatly underestimated metal mobility in the field and that preferential flow, both alone and in combination with organic-facilitated transport, can accelerate metal leaching through soils. 32 refs., 4 figs., 5 tabs.« less

286 citations



Journal ArticleDOI
TL;DR: The total specific surface area (SA) is a factor that can relate grain-scale properties to macro-scale physical and chemical properties of a porous medium as mentioned in this paper, and it is, therefore, advantageous to establish the relationships between SA and general soil physical properties.
Abstract: The total specific surface area (SA) is a factor that can relate grain-scale properties to macro-scale physical and chemical properties of a porous medium. It is, therefore, advantageous to establish the relationships between SA and general soil physical properties. In this study we investigated

234 citations


Journal ArticleDOI
TL;DR: The influence of the amount and kinds of organic and inorganic amendments on phosphorus (P) sorption characteristics was determined on two soils from Oregon, Jory (Xeric Haplohumult) and Tolo (Typic Vitrandept), and three soils from Rwanda, Mata (Sombrihumult), Kibeho (Paleudult), and Kinigi as mentioned in this paper.
Abstract: The influence of the amount and kinds of organic and inorganic amendments on phosphorus (P) sorption characteristics was determined on two soils from Oregon, Jory (Xeric Haplohumult) and Tolo (Typic Vitrandept), and three soils from Rwanda, Mata (Sombrihumult), Kibeho (Paleudult), and Kinigi (Typic

201 citations



Journal ArticleDOI
TL;DR: In several experiments with soils and mineral phases, extraction of Al (and Fe) by pyrophosphate reagent (0.1 M Na4P2O7, pH 9.5 - 10.5) was tested with regard to its use for the characterization of Al in humus complexes.
Abstract: In several experiments with soils and mineral phases, extraction of Al (and Fe) by pyrophosphate reagent (0.1 M Na4P2O7, pH 9.5 - 10.5) was tested with regard to its use for the characterization of Al in humus complexes. Results showed that, independent of the soil content of organic C, pyrophosphat

Journal ArticleDOI
TL;DR: In this paper, 13 C nuclear magnetic resonance (13 C NMR) and pyrolysis-field ionization mass spectrometry (Py-FIMS) were used to characterize plant tissue, isolated fractions, and whole surface soils and subsoils from a forest system and a maize (Zea mays L.) system.
Abstract: During the stabilization of plant residues into soil humus, organic matter is transformed continuously to different chemical compounds. To obtain a better understanding of these changes, we used 13 C nuclear magnetic resonance ( 13 C NMR) and pyrolysis-field ionization mass spectrometry (Py-FIMS) to characterize plant tissue, isolated fractions, and whole surface soils and subsoils from a forest system and a maize (Zea mays L.) system. Both methods indicated that chemical components of the light fraction (LF) were similar to those in the plant material from which the LF was derived, but a lesser amount of carbohydrates and a greater amount of sterols in the LF signalled the early stages of decomposition of organic matter in soil. Accumulation of alkyl C in the maize LF was attributed to microbial structures or metabolites. Larger differences in the abundance and range of organic components were observed between the LF and sand-size fraction (SSF) of the soil under maize. The mass spectra showed that fewer lignin monomers and dimers, lipids, and alky-aromatic compounds were present in the SSF compared with the LF. Carbon-13 NMR data indicated that the SSF contained relatively lesser amounts of carbohydrates and aliphatic compounds and had a higher degree of aromaticity than the LF. Differences between the organic matter in the soils under forest and maize reflected the effects of deforestation, cultivation, and cropping to maize on soil organic matter. Carbon-13 NMR results indicated that the surface soil under maize had less O-alkyl and alkyl C but more aromatic and carboxyl C than the forest soil. In addition, Py-FIMS results indicated that lipids and sterols, which are derived from plant material, were reduced in the soil under maize. Microbial degradation of these high-molecular-weight compounds probably resulted in their transformation into polysaccharides in the soil humus. The presence of numerous N-compounds in the soils under maize was attributed to N from fertilizers that had been stabilized in heterocyclic forms.

Journal ArticleDOI
TL;DR: In this article, a review of the mechanisms of sorption/desorption phenomena at the mineral/water interface is provided and a brief discussion of macroscopic, equilibrium approaches for describing sorption processes is provided.
Abstract: Sorption is one of the most important chemical processes in soil. It affects the fate and mobility of nutrients and contaminants in soils and waters greatly. This per critically reviews the mechanisms of sorption/desorption phenomena at the mineral/water interface. A brief discussion of macroscopic, equilibrium approaches for describing sorption processes is provided. However, emphasis will be placed on the importance of understanding the rates of sorption/desorption processes and coupling the kinetic investigations with in-situ atomic/molecular resolution surface techniques. The use of X-ray absorption fine structure (XAFS) spectroscopy and scanning force microscopy (SFM) will be emphasized.

Journal ArticleDOI
TL;DR: In this article, the authors quantify the spatial variability and spatial crosscorrelation of estimated parameter values of a flexible retention model that was used for water flow and solute transport calculations in variably saturated soils.
Abstract: Unsaturated hydraulic properties of field soils are needed for water flow and solute transport calculations in variably saturated soils. The purpose of this study was to quantify the spatial variability and spatial crosscorrelation of estimated parameter values of a flexible retention model that was


Journal ArticleDOI
TL;DR: In this paper, a detailed account of wind erosion processes within a single agricultural field during a regional dust storm in the Southern High Plains of West Texas was obtained. But the field, located in Wolfforth, Texas, was observed as the wind grew in strength, peaked, and later weakened.
Abstract: The goal of this field study was to obtain a detailed account of wind erosion processes within a single agricultural field during a regional dust storm in the Southern High Plains of West Texas. The field, located in Wolfforth, Texas, was observed as the wind grew in strength, peaked, and later weakened. Sediment transport was monitored by an array of samplers spaced across the field, and meteorological information was obtained from a 10-m tower erected within the field. Erosion activity was monitored by a piezoelectric sensor that responded to the impact of saltating grains and provided a means for detecting the threshold of soil movement. Attempts were made to relate the observed temporal and spatial variations of sediment transport to meteorological factors and surface conditions. The results indicate that at the beginning of the storm, threshold was around 7 to 8 m/s. As the storm progressed, threshold appeared to slowly shift downward with time, suggesting a surface that was becoming increasingly erodible. Mass flux measurements showed substantial temporal variations that reflected changes of wind strength and changes in surface erodibility. The pattern of mass flux variation across the field was dependent on the height of measurement. The near surface flow of saltating grains (z < 0.25 m) was found to vary according to surface conditions, especially surface roughness. At greater heights, the flow of fine dust was less affected by surface conditions immediately beneath the point of measurement. Within the fully developed surface layer (z < 0.25 m), the mass flux profile was found to follow a modified powerlaw function. The near surface mass flux consisted of a broad range of particle sizes ranging from 50 μm to 300 μm, whereas farther from the surface the mode shifted distinctly toward smaller particle sizes with few particles larger than 100 μm. We show that it is possible to display graphically the relative contribution of the various grain sizes to the mass flux at each height in a way that makes it possible to visualize the zones of saltation and suspension, and the region of transition between these regimes.

Journal ArticleDOI
TL;DR: In this paper, the authors found that organic amendments decreased P sorption that was related to changes in some soil chemical properties (e.g., pH and exchangeable Al), and that addition of organic residue to soils may also affect P Sorption by adding PO4 (Pi) or releasing organic P (Po) during mineralization.
Abstract: Previously, we found that organic amendments decreased P sorption that was related to changes in some soil chemical properties (e.g., pH and exchangeable Al). However, addition of organic residue to soils may also affect P sorption by adding PO4 (Pi) or releasing organic P (Po) during mineralization

Journal ArticleDOI
TL;DR: The amounts of C, N, and P stored in soils represent the balance between inputs and outputs of these elements to and from terrestrial ecosystems, and unintentional perturbation of element cycles may profoundly influence soil organic matter and associat
Abstract: The amounts of C, N, and P stored in soils represent the balance between inputs and outputs of these elements to and from terrestrial ecosystems. Soil management and unintentional perturbation of element cycles (e.g., inputs of pollutants) may profoundly influence soil organic matter and associat

Journal ArticleDOI
TL;DR: In this article, three metal-contaminated soils (Fuquay, Dothan, and Clarendon) were selected from cropland where a high-meta
Abstract: Heavy metal movement in soil profiles is a major environmental concern because even slow transport through the soil may eventually lead to deterioration of groundwater quality. In this study, three metal-contaminated soils (Fuquay, Dothan, and Clarendon) were selected from cropland where a high-meta

Journal ArticleDOI
TL;DR: In this article, the Proctor test on a total of 36 samples from four Kentucky soils was used to determine the maximum compaction of the soil and showed that compact soils are more compact after continuous no-tillage.
Abstract: With the practice of continuous no-tillage, the question arises of whether, after a period of time, some sort of mechanical tillage will be required to alleviate compaction. Studies of maximum compaction using the Proctor test on a total of 36 samples from four Kentucky soils revealed that compactab


Journal ArticleDOI
TL;DR: In this article, the authors have shown that the inclusion of a first-order reaction term in the model is necessary for accurate calculation of stimultaneous diffusion and reaction in soil systems is a prerequisite for realistic model simulations of diffusion controlled chemical fate processes and analysis of experimental data.
Abstract: Numerically accurate calculation of stimultaneous diffusion and reaction in soil systems is a prerequisite for realistic model simulations of diffusion-controlled chemical fate processes and analysis of experimental data. Recent studies have shown that the inclusion of a first-order reaction term in

Journal ArticleDOI
TL;DR: In this article, the Campbell soil-water retention function was used to predict gas diffusivity in soils, which is essential to the development of better gas transport and fate models.
Abstract: Improved prediction of gas diffusivity in soils is essential to the development of better gas transport and fate models. Empirical equations analogous to three well known capillary tube models for unsaturated hydraulic conductivity, based on the Campbell soil-water retention function, were used to p

Journal ArticleDOI
TL;DR: The proposed criteria for Andosol classification in the World Reference Base (WRB) of Soil Resources were evaluated using the Tohoku University World andosol Database (TUWAD).
Abstract: The proposed criteria for Andosol classification in the World Reference Base (WRB) of Soil Resources were evaluated using the Tohoku University World Andosol Database (TUWAD). The WRB proposal defines a diagnostic andic horizon comprised of vitr-andic, alu-andic, and sil-andic subtypes, and eight

Journal ArticleDOI
TL;DR: In this article, the inhibition of each component on the activity of a free enzyme and the residual activity of the enzymatic complexes have both been determined, and it was shown that the presence of OH-Al species during the interaction between the two components favored the entrapment of more enzymes at higher activity levels.
Abstract: Synthetic active enzymatic complexes have been formed by the interaction of acid phosphatase with clays (montmorillonite and chlorites), organic molecules, and organo-mineral associations. The inhibition of each component on the activity of the free enzyme and the residual activity of the enzymatic complexes have both been determined. Clays and tannic acid displayed various inhibitory effects on acid phosphatase activity. Montmorillonite and aluminum hydrous oxide showed the highest (70%) and the lowest (<5%) inhibitory influence, respectively. The covering of montmorillonite surfaces with OH-Al species increased not only the amount but also the residual activity of adsorbed acid phosphatase molecules. When 18 meq of Al g -1 clay were adsorbed on montmorillonite surfaces, the residual activity of adsorbed enzyme increased up to 54% of that added initially. The activity retained by tannate-acid phosphatase complexes depended on incubation time and tannic acid/enzyme ratios. This suggests that a complexation between tannic acid and enzyme molecules, rather than a polymerization process of tannic acid involving acid phosphatase, took place. The presence of OH-Al species during the interaction between the two components favored the entrapment of more enzymatic molecules at higher activity levels.


Journal ArticleDOI
TL;DR: Two weighing lysimeters were installed at the University of Arizona's Karsten Center for Turfgrass Research to measure evapotranspiration (ET) and to perform water use and deep percolation experiments in a deep soil profile under both natural precipitation and irrigation conditions as discussed by the authors.
Abstract: Two weighing lysimeters were installed at the University of Arizona's Karsten Center for Turfgrass Research. The goals of the facility are to measure evapotranspiration (ET) and to perform water use and deep percolation experiments in a deep soil profile under both natural precipitation and irrigation conditions. Each lysimeter is 4.0 m deep, 2.5 m in diameter, and equipped with 96 sampling ports for soil solution samplers, tensiometers, time domain reflectometry (TDR) probes, and thermocouples. The weighing scales have a capacity of 45 Mg and can detect a 200-g mass change, equivalent to ± 0.04 mm of water on the surface. The lysimeters were filled with Vinton fine sand (sandy, mixed thermic Typic Torrifluvent). Monitoring the unvegetated lysimeters for 18 weeks indicated that about 66% of all precipitation percolated into the soil profile. In June 1994, the lysimeter surfaces and surrounding area were planted with 'Tifway' bermudagrass (Cynodon dactylon x transvaalensis var. Tifway), and irrigation began. Three phases of turf water use were identified during the first 155 days after planting-establishment, full cover and over-seeding. The percentage of water that percolated into the soil profile deeper than the root zone was 35.6%, 10.1%, and 48.3%, respectively, showing the effectiveness of active root water uptake in reducing deep percolation. The TDR, neutron probe and tensiometer methods provided very similar indications of the depth of the wetting front. Differences in depth estimates could be caused by differences in sampling volume among the three methods. The TDR and neutron probe provided estimates of soil water storage that usually were within 10% of one another, and consistent with changes in lysimeter mass.

Journal ArticleDOI
TL;DR: In this article, a study was carried out with the aim of elucidating the precise effects of different soil management practices on total organic matter and its particle size fractions in soils of the semi-arid pampa region.
Abstract: Because the level of organic matter in soils can reflect the intensity of soil utilization, the present study was carried out with the aim of elucidating the precise effects of different soil management practices on total organic matter and its particle size fractions in soils of the semiarid pampa region. Surface samples of 52 entic Haplustolls under three different uses (24 under continuous cropping, 18 under rotation with grass leys and 10 virgin soils) were analyzed in terms of clay, total organic matter content and organic matter particle size fractions. The obtained data show that organic matter fractions differ according to particle size distribution and the prevailing soil management system. Stable organic matter content ( 100 μm) is strongly influenced by the type of soil management utilized.

Journal ArticleDOI
TL;DR: In this article, the results of an intensive study of the clasts from three profiles in the Vallombrosa Forest 50 km east of Florence, Italy, have established that the coarse fraction of this fraction, especially those altered and partially altered, manifest properties that in some cases equal or surpass those of more reactive fine earth.
Abstract: During sample preparation, the coarse fraction (> 2 mm) of soils is commonly excluded from further analytical determinations. Our results demonstrated, however, that the coarse fragments of soils derived from sandstone in Tuscany, Italy, are not chemically inert. From an intensive study of the clasts from three profiles in the Vallombrosa Forest 50 km east of Florence, we have established that the clasts of this fraction, especially those altered and partially altered, manifest properties that in some cases equal or surpass those of the more reactive fine earth. The profiles are underlain by Arenaria del Falterona, a sandstone of the Oligocene time intercalated with siltstone. Our research shows that the coarse fraction participates in a sequence of weathering events that involves dissolution of carbonates and formation and transformation of secondary minerals. Although fresh sandstone and siltstone display distinct mineralogical composition, these differences are not maintained once they undergo accelerated weathering in the soil. Dissolution of carbonate brings indirect enrichment of the noncarbonatic components. Formation of HIV (hydroxy interlayered vermiculite) and HIS (hydroxy interlayered smectite) is the dominant process in the fine earth and clasts. This process becomes particularly important in stabilizing the micropores of the clasts and maintaining a porosity that allows the soil solution to be adsorbed and circulate. Weathering processes thus create voids, release nutrient cations, and render the most weathered clasts similar to fine earth. The progression of weathering into the clasts is demonstrated by the levels of extractable Fe and Al obtained by selective dissolution. Furthermore, our research shows that the rock fragments contain C and N in considerable quantities and have a higher pH and a mineral assemblage less weathered than the fine earth. In addition, clasts constitute a reservoir for nutrients and possess a capacity for proton consumption. Moreover, although the fine earth, including organic matter, dominates the effective cation exchange capacity (ECEC) in the upper horizons, in the B and BC horizons the rock fragments represent from 20 to 55% of the total ECEC. In conclusion, our findings show that the clasts of these reactive lithologies are not inert but play all important role in soils as: (i) reservoirs of nutrients, including N, (ii) sources of cation exchange capacity, (iii) water supplies, (iv) adsorbers of organic pollutants, and in the consumption of protons.

Journal ArticleDOI
TL;DR: In this article, no quantitative information about changes in soil cation exchange capacity caused by changes in organic matter content as a function of soil organic carbon content and clay content is provided.
Abstract: Soil cation exchange capacity (CEC) is important in plant nutrient uptake and ion movement and is highly correlated with organic carbon content and clay content of soil. However, there is no quantitative information about changes in soil CEC caused by changes in soil organic matter content as a r