bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil Water Content Determination Using a Digital Ground‐Penetrating Radar
Authors: Chanzy A. , Tarussov A. , Bonn F. , Judge A. 
Published: July 2010

AbstractWe evaluated the potential of a digital ground‐penetrating radar (GPR) for soil moisture determination. Ground‐penetrating radar offers a fast and nondestructive way for estimating the soil dielectric constant and may be an interesting tool for low‐cost mapping of soil moisture. Two modes of operation were considered: (i) the ground mode where signal propagation between the antennas placed on the surface was studied; (ii) the airborne mode where the antennas are raised 5–15 m above the soil surface. Variables describing the GPR response were defined and related to the soil moisture. It is shown from field experiments that the GPR measurements performed at 200 MHz in both modes are mainly affected by the moisture in the 10‐ to 20‐cm topsoil layer. In the ground mode, the obtained soil moisture error after calibration was lower than 0.03 m3/m3. In the airborne mode, soil moisture estimations were less accurate (0.046 m3/m3). The wave spreading loss characterization has to be improved to get an altitude‐independent GPR measurement.
Chloride Increases Cadmium Uptake in Swiss Chard in a Resin‐buffered Nutrient Solution
Authors: Smolders E. , McLaughlin M. J. 
Published: July 2010

AbstractOne of the possible hypotheses to explain the high Cd availability at elevated Cl concentration in soil is that chloro‐complexes of Cd are available for root uptake. In order to test this hypothesis, Swiss chard [Beta vulgaris ssp. cicla (L.) Koch, cv. Fordhook Giant) was grown in nutrient solution continuously recirculated over a chelating resin (Chelex‐100) partially loaded with Cd. Treatments were increasing concentrations of Cl (0.01, 40, 80, and 120 mM) in the nutrient solution with fourfold replication. Solution Na concentrations and ionic strengths were equalized in all treatments by compensating with NaNO3. Increasing Cl concentrations in solution did not affect dry weights of either roots or shoots. Activity of Cd2+ in solution was well buffered during plant growth using the resin system. Complexation of Cd2+ by Cl increased soluble Cd in culture solutions but the calculated activity of Cd2+ was not significantly affected by increasing concentrations of Cl in solution. As solution Cl concentration increased, Cd concentrations in plant shoots increased from 6.5 to 17.3 mg kg−1 and in roots from 47 to 106 mg kg−1. We concluded that enhancement of Cd uptake by Cl in soils need not be related only to enhanced diffusion of Cd2+ through soil to the root but that (i) CdCl2‐nn (in addition to Cd2+) species in solution are phytoavailable and/or (ii) Cl enhances diffusion of Cd2+ through the unstirred liquid layer adjacent to the root surface or through the apoplast to sites of Cd uptake within the root itself.
Dynamics of Soil Physical Properties in Amazonian Agroecosystems Inoculated with Earthworms
Authors: Alegre J. C. , Pashanasi B. , Lavelle P. 
Published: July 2010

AbstractThe combined use of earthworm inoculation and organic inputs is considered an efficient way to improve traditional slash‐and‐burn agriculture in the humid tropics. This study tests the hypothesis that the resistant macroaggregate structure that results from earthworm activities is likely to promote sustainability by favoring water infiltration and soil aeration. Six successive crops (maize [Zea mays L.]‐rice [Oryza sativa L.]‐cowpea [Vigna unguiculata (L.) Walp.]‐rice‐rice‐rice) were grown from March 1990 to January 1993 on a fine‐sandy, siliceous, isohyperthermic Typic Paleudult previously covered by forest at Yurimaguas (Peruvian Amazonia). The experimental design included a combination of three organic residue treatments (without residues, with crop residues, and with crop residues plus green manure), with or without earthworm (Pontoscolex corethrurus) inoculation (36 g fresh weight m−2). Soil physical properties (bulk density, total porosity, infiltration, sorptivity, soil water tension, and aggregate‐size distribution) were measured before clearing and after harvesting each crop. The proportion of macroaggregates (>1 cm) increased from 25.1 to 32.7% in inoculated treatments, whereas the proportion of small aggregates (<2 cm) decreased from 33.2 to 26.1%, and no change was observed in the intermediate (2‐10 mm) category. In the control treatment, no significant changes were observed. Earthworm activities significantly increased bulk density (from 1.12 to 1.23 Mg m−3), and decreased porosity (from 58 to 53%) and sorptivity (from 0.45 to 0.15 cm s−1/2). Soil water tension was also affected by the presence of earthworms through increased water uptake by larger plants and changes in soil structure. Longer term experiments are necessary to confirm that the activity of the earthworm may not eventually have detrimental effects.
Factors Affecting Phosphate Rock Dissolution in Acid Soil Amended with Liming Materials and Cellulose
Authors: He Z. L. , Baligar V. C. , Ritchey K. D. , Martens D. C. , Kemper W. D. 
Published: July 2010

AbstractCoal combustion by‐product (CCBP; a wallboard‐quality gypsum), limestone, and cellulose had been found to influence the dissolution of North Carolina phosphate rock (NCPR) in an acid Lily loam soil (fine‐loamy, siliceous, mesic Typic Hapludult). Laboratory and incubation experiments were carried out in this study to elucidate the mechanisms responsible for the reduced dissolution of NCPR from CCBP application. The major factors responsible for the reduced PR dissolution were (i) an increase in exchangeable Ca + Mg derived from the CCBP, (ii) an increase in soil pH from the small amounts of CaCO3 in the CCBP material; and (iii) sulfate released from the CCBP resulting in a decrease in P sorption capacity of the amended soil due to competitive sorption between sulfate and phosphate. The further reduction in NCPR dissolution by limestone addition was probably due to the increase in pH and exchangeable Ca relative to CCBP application alone. An increased NCPR dissolution from cellulose addition probably reflected an accelerated depletion of labile P by the cellulose‐induced microbial growth and, hence, biomass production. The four kinetic dissolution parameters, i.e., the half‐life (t1/2) from a first‐order rate equation, the initial dissolution rate‐ and the average dissolution rate‐related constants (A and b) from an Elovich equation, and the potential maximum dissolution of phosphate rock from a Langmuir equation were significantly correlated with pH, the content of exchangeable (Ca + Mg), and P sorption capacity of the CCBP‐amended soil. The t1/2 and A of NCPR in the acid soil could be predicted with 95% confidence by the three soil variables, i.e, soil pH, P sorption capacity, and exchangeable (Ca + Mg). Both t1/2 and A could serve as an indicator of the NCPR dissolution potential in soils.
Sustained Productivity of Forests Is a Continuing Challenge to Soil Science
Authors: Nambiar E. K. Sadanandan 
Published: July 2010

AbstractScientific uncertainties about ecosystem processes and greater awareness of the need for environmental care are sources of public anxiety over forest management. Partly because of this, the negative impacts of poor forestry practices are often emphasized, overlooking the achievements in sustainable forestry. The forest estates should be viewed and managed as a continuum so that the overall need for production of wood and the protection of environmental values can be met. We need practical goals of forest management. One goal should be to ensure that the trend in forest productivity is nondeclining or is positive through successive rotations and harvests, while maintaining and enhancing the quality of the soil resource base in perpetuity. The conflicts about the use of native forests for wood harvesting, while maintaining all conservation values, can be lessened if the value of each forest is ranked within a scale ranging from wood production to conservation. The growing demand for wood and concerns for land care can be met in part by expanding plantation forestry. Questions concerning management strategies for sustainable forestry are global in scope, but the genesis and application of practices for achieving this are local and are based fundamentally on the soil. The expectation of developing soil‐based sustainability indicators can be realized only if the expectation is backed by substantial research linking changes in soil properties, ecosystem processes, and productivity at the landscape level. Challenges are many and include interdisciplinary approaches to research and forest management, application to ensure economic prosperity, and positive approaches to communication.
Changes in the Biogeochemistry of Potassium following a Whole‐Tree Harvest
Authors: Romanowicz Rachel B. , Driscoll Charles T. , Johnson Chris E. , Fahey Timothy J. , Likens Gene E. , Siccama Thomas G. 
Published: July 2010

AbstractA whole‐tree harvest (WTH) was conducted at the Hubbard Brook Experimental Forest, New Hampshire, in 1983–1984 to evaluate changes in the loss and supply of nutrients such as K in response to clear‐cutting. The WTH removed 554 mmol m−2 associated with forest biomass. During the first 2 yr following the WTH, there were marked increases in concentrations and fluxes of K in drainage waters (stream efflux 24 mmol m−2 yr−1), coinciding with elevated losses of NO3−. While these losses decreased within 3 yr, concentrations and fluxes of K remained high in Bs2 horizon soil water and streamwater (10.5 mmol m−2 yr−1) for 10 yr relative to the reference watershed (4.8 mmol m−2 yr−1). Soil exchangeable K pools increased within 3 yr after the WTH. In the high‐elevation zone of the watershed, soil pools returned to near‐preharvest values after 8 yr. In the remainder of the watershed, exchangeable K pools decreased after 8 yr but remained about 20% above preharvest pools. The increase in exchangeable K in the mineral soil probably contributes to the long‐term pattern of elevated K concentrations in streamwater after the WTH. Although stream and WTH removal of K (8.5 mmol m−2 yr−1) was large in comparison to preharvest exchangeable K pools (284 mmolc m−2), the increased release of K from mineralization of soil organic matter and weathering resulted in an increase in K on the soil exchange complex (43 mmol m−2 yr−1 in the first 8 yr). The increase in exchangeable K provided an available pool of K for the regrowing vegetation.
Testing an Artificial Neural Network for Predicting Soil Hydraulic Conductivity
Authors: Tamari S. , Wösten J. H. M. , Ruiz‐Suárez J. C. 
Published: July 2010

AbstractMultilinear regression has been used extensively to predict soil hydraulic properties, both the θ(h) and K(h) relationships, from easily obtainable soil variables. As an alternative, this study investigated the performance of an artificial radial basis neural network in predicting some K(h) values from other variables. This kind of neural network may be seen as a multivariate interpolation technique, which can theoretically fit any nonlinear continuous function. Neural networks are characterized by parameters that must be optimized to solve a given problem. We used a fitting procedure requiring only two parameters to ensure a unique solution. These two parameters were determined by data splitting. Hypothetical data bases with uncertainties were simulated to analyze the performance of the neural network in predicting a nonlinear relation derived from a classical model for K(h). A soil data base covering a broad spectrum of soil horizons was used to test the neural network in solving multivariate problems. Numerical simulations showed that the neural network was sensitive to large uncertainties in the data base. It was more efficient than a multilinear regression when the uncertainties were small. Experimental results showed that the neural network was more efficient than the multilinear regression for predicting K(h = −1 m) or K(h = −2.5 m) from two qualitative and five quantitative soil variables. It was also more efficient than two independent multilinear regressions, one for the sandy samples and the other for the loamy and clayey samples. Provided that a large data base with accurate K values is available, artificial neural networks can be useful to predict θ(h) and K(h) over a broad spectrum of soils.
Simultaneous Measurement of Soil Microbial Nitrogen, Carbon, and Carbon Isotope Ratio
Authors: Bruulsema T. W. , Duxbury J. M. 
Published: July 2010

AbstractMethods used for analysis of soil microbial biomass N and C are limited in precision and are time consuming. A method involving direct combustion of evaporated soil extracts was developed for use with an automated nitrogen and carbon analyzer (ANCA). The objectives of this study were to: (i) evaluate the usefulness of ANCA determination of microbial C and N, and (ii) ascertain whether the microbial C isotope ratios determined by the ANCA method would reflect C contributions from actively growing crops of wheat (Triticum aestivum L.) and maize (Zea mays L.) differing in C isotope ratio. Cropped and fallow soils were sampled at planting, anthesis, and maturity. Field‐moist soils were fumigated with chloroform and extracted with 0.05 M K2SO4 for the ANCA method and with 0.5 M K2SO4 for Kjeldahl analysis. Small volumes of the 0.05 M K2SO4 extracts were evaporated on cone‐shaped tin disks that were analyzed using combustion at 1700°C and mass spectrometry. Reproducible values for C, N, and δ13C were obtained with less effort than that typically expended for Kjeldahl N analysis of similar extracts. Temporal changes in microbial δ13C occurred in both cropped and fallow soils during a single growing season. At maturity of the maize crop, an estimated 23% of the soil microbial C was derived from the plant material of the current maize crop. Carbon contribution from the wheat crop to the soil microbial biomass was not detected. Further refinements in the ANCA method may make the procedure routinely usable for enhancing the understanding of chloroform labile C and N as indicators of microbial dynamics in the soil.
Myrosinase Activity in Soil Extracts
Authors: Borek Vladimir , Morra Matthew J. , McCaffrey Joseph P. 
Published: July 2010

AbstractMyrosinase (β‐thioglucoside glucohydrolase; EC 3.2.3.1) catalyzes the hydrolysis of glucosinolates to form a variety of potential allelochemicals. Although these allelochemicals may exert an influence on soil‐borne organisms, the extracellular preservation of plant‐derived myrosinase in soil has not been determined. Soil samples from a field of rapeseed (Brassica napus L.) and from a pasture were extracted with a 0.1 M mixture of K2HPO4 and disodium ethylenedinitrilotetraacetate (pH 7.9). Crude extracts were purified with dialysis and assayed for enzymatic activity using sinigrin (allyl glucosinolate) as a substrate. Myrosinase activity was evaluated by monitoring the hydrolysis product, allyl isothiocyanate, using gas chromatography. Reliability and limitations of the assay were verified with autoclaved samples amended with known amounts of enzyme of allyl isothiocyanate. Extracts of soil samples from a rapeseed field showed myrosinase activity, whereas extracts from a pasture soil showed no detectable activity. Highest myrosinase activity was detected in soil sampled directly from rapeseed rows, an activity equivalent to a myrosinase concentration of approximately 20 µg kg−1 soil. Soil sampled between rapeseed rows had a lower myrosinase activity equivalent to a myrosinase concentration of approximately 5 µg kg−1 of soil. The presence of extracellular myrosinase in soil indicates that glucosinolate hydrolysis in the rhizosphere of Brassica spp. and allelochemical impacts on organisms within the rhizosphere are possible.
Soil Surface Coatings at Costa Rican Recently Active Volcanoes
Authors: Jongmans A. G. , Groenesteijn K. , Buurman P. , Mulder J. 
Published: July 2010

AbstractUnvegetated slopes of recently active volcanoes in perudic Costa Rica have locally thin, hard, laminated coatings at the soil surface. These coatings, which cover both ash deposits and boulders, are actively forming in some locations and eroding in others. We investigated the chemistry and formation of these coatings. Optical analysis of the coatings shows that they consist of anisotropic ash particles embedded in isotropic, translucent, fine‐textured amorphous material. Scanning electron microscope analysis clearly shows secondary coatings covering and cementing primary mineral grains and rock fragments. In situ microchemical analysis shows that the coatings consist predominantly of silica. Primary mineral grains in well‐developed coatings may also be replaced by silica. The internal fabric of the coatings suggests that accumulation of secondary silica and deposition of (reworked) ash are simultaneous processes and that all coatings were formed in various episodes. Precipitation of secondary silica from solution may occur where rapid weathering of primary minerals (volcanic ash) combined with high deposition of strong acids (HCl, H2SO4) from fumarolic and solfataric activity results in high dissolved Si concentrations. This process is further enhanced by evaporative concentration at the soil surface. Low pH precludes formation of secondary aluminium silicates and gibbsite. Erosion of the coatings seems to be largely due to episodically transported water.
Mineral and Organic Fractions of Two Oxisols and Their Influence on Effective Cation‐Exchange Capacity
Authors: Mendonça Eduardo S. , Rowell David L. 
Published: July 2010

AbstractThe mineral and organic fractions of a clayey Red Yellow Latosol (Typic Acrustox) and a sandy loam Dark Red Latosol (Typic Haplustox) sampled under the Cerrado Region of Brazil were characterized, and their influence on the effective cation‐exchange capacity was evaluated. Kaolinite and sesquioxides dominate the clay fraction of both soils, but the clayey soil is at a more advanced stage of weathering. It also holds a larger amount of organic matter and has more fulvic acid than humic acid throughout the profile. In the sandy soil, the reverse applies to the surface horizon, with equal amounts of humic and fulvic acids in lower horizons. More humic and fulvic acids were extracted from both soils by NaOH than by Na4P2O5, with CaHPO4 and water extracting similar small amounts of C. The total acidity, the carboxyl groups, and the phenolic‐OH groups were measured in humic and fulvic acids. The humic acid was about half as reactive as the fulvic acid in both soils. Fulvic acid is therefore the main source of charge in the clayey soil, but in the surface horizon of the sandy soil, humic acid contributes to more charge. The soils have low effective cation‐exchange capacity values, which decrease with depth and depend primarily on the content of organic matter, as shown by regression and multiple regression analysis.
Color Index for Identifying Hydric Conditions for Seasonally Saturated Mollisols in Minnesota
Authors: Thompson James A. , Bell James C. 
Published: July 2010

AbstractThe thick surface accumulations of organic matter in Mollisols confound the possibility of recognizing soil morphological features such as redoximorphic features that indicate seasonally saturated and reduced soils. The most obvious morphological change in the soil across Mollisol hydrosequences in Minnesota is the thickening and darkening of the A horizon(s). Our purpose is to quantify this trend across the landscape and examine its correlation with duration of saturated and/or reducing conditions for distinguishing between hydric and nonhydric Mollisols. We examined trends in soil morphology and soil organic C in conjunction with hydrologic monitoring data across three Mollisol hydrosequences. We defined a new color index that is a function of the thickness and color of the A horizon(s) of Mollisols of three hillslopes in Minnesota. Coefficients of correlation (r) between this index and duration of saturated and reducing conditions at various depths in these Mollisols are as high as 0.69. This index is also linearly related to organic C content of the A horizon(s) of a single hillslope with a coefficient of correlation of 0.98. This index may be useful for identifying and delineating hydric soils and may be employed to examine soil C storage at a landscape scale; however, specific relationships will vary considerably with soil parent material and climate.
Early Teaching in USA of Dokuchaiev Factors of Soil Formation
Authors: Simonson Roy W. 
Published: July 2010

AbstractTeaching of the factors of soil formation first recognized by Dokuchaiev began in the USA in the late 1920s and early 1930s. Reports on their functions had been available in English prior to and early in the 20th century, but Americans were not receptive to the Russian idea of five factors, still holding that soil formation consisted of rock weathering. Following the First International Congress of Soil Science and related activities in 1927, however, the Dokuchaiev factors were soon introduced in pedology courses, first by J.C. Russell in Nebraska and next by Charles E. Kellogg in North Dakota. Basically the same for the two men, the presentation of the five factors illustrated here is from the course taught by Kellogg in 1932. The presentation was chiefly a combination of lectures and reading assignments but included limited field study. Slightly less than half of the lectures in a three‐hour course were about the factors of soil formation. Evident now, the lectures and reading assignments reflect the state of knowledge of their day, including both gaps and errors. At the same time, the coverage is impressive when considered against the limited study of soils in the world accomplished up to that time.
Copper Solubility in Myersville B Horizon Soil in the Presence of DTPA
Authors: Vulava Vijay M. , Torrents Alba , James Bruce R. 
Published: July 2010

AbstractOrganic ligands greatly affect the speciation and solubility of heavy metals in soils, depending on complex interactions of pH, ligand‐to‐metal ratio, and the order of application of metals and ligands to soils. To understand how these variables influence the fate of metals added to soil, we investigated the solubility of Cu(II) in Myersville B horizon soil (Ultic Hapludalf) in the presence of diethylenetriaminepentaacetic acid (DTPA), a strong complexing agent. Copper solubility was studied as a function of soil pH, individual and relative concentrations of Cu2+ and DTPA, and the order of application of these components to the soil. In the presence of DTPA (1.0 and 10 mmol kg−1 soil), Cu(II) solubility (0.1 and 1.0 mmol kg−1 soil) increased with an increase in pH (4 to 7). However, this occurred only when DTPA concentration ≥ Cu(II) concentration, implying that the relative concentrations of DTPA and Cu(II) were critical in controlling Cu(II) solubility. The order of application of Cu(II) and DTPA to the soil also strongly influenced Cu solubility. The three orders of application of these components were (i) application of premixed stock solutions of Cu(II) and DTPA in specified ratios and concentrations to the soil, (ii) equilibration of Cu(II) with the soil followed by application of DTPA, and (iii) equilibration of DTPA with soil followed by Cu(II) application. Of these three, the highest Cu solubility was observed in the third case when DTPA > Cu(II). This was attributed to surface coordination of DTPA, which prevents Cu from binding with soils. Also, an increase in background electrolyte concentration was accompanied by a decrease in the pH and, therefore, a change in Cu(II) solubility. These results have several implications in the field of contaminant and nutrient management in soils.