bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tillage and Canopy Cover Effects on Interrill Erosion from First‐Year Alfalfa
Authors: Sturgul S. J. , Daniel T. C. , Mueller D. H. 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.) establishment techniques commonly produce a soil surface susceptible to high runoff and soil losses prior to crop canopy development. Limited data are available on the erodibility and productivity of alfalfa seedbeds established with conservation tillage systems. Four alfalfa establishment techniques were investigated for runoff, erosion, and forage yield over two growing seasons on a Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudoll) with a 5% slope in south‐central Wisconsin. Alfalfa seedbeds were established on cropland previously in no‐till (NT) corn (Zea mays L.). Five simulated rainfalls were applied to moldboard (MB), moldboard‐nurse crop (MB/nc), chisel (CH), and NT alfalfa seedbeds. An additional seedbed investigated was no‐till with surface residue removed (NT/wo) immediately prior to rainfall simulation. Relative to MB, CH treatments reduced runoff volumes by 23 to 72% and NT treatments reduced volumes 59 to 100%. Soil‐loss reductions of 24 to 64% from CH and 71 to 100% from NT relative to MB were observed. Runoff volumes from NT/wo were the largest of all treatments for four of the five rainfall simulations. Soil losses from NT/wo were statistically similar (P = 0.05) to MB for all rainfall simulations. Comparisons of MB to MB/nc runoff volumes did not indicate an influence of canopy cover on runoff. A MB/nc soil loss of 87% less than MB at a rainfall simulation with MB/nc canopy cover of 93% relative to MB canopy cover of 47% did indicate a canopy effect on soil loss. No significant influence of canopy development on runoff volumes from similar treatments over time was evident. Canopy development contributed to reduced soil losses within all treatments, with a maximum reduction of 96% observed for MB/nc canopy cover of 93% relative to MB/nc soil loss at 0% canopy. Establishment year alfalfa yield and quality did not vary among MB, CH, and NT treatments at a significance level of P = 0.05.
Infiltration in Adjacent Cecil and Pacolet Soils
Authors: Radcliffe D. E. , West L. T. , Ware G. O. , Bruce R. R. 
Published: July 2010

AbstractCecil (clayey kaolinitic, thermic Typic Kanhapludult) and associated soils cover two‐thirds of the land area of the Southern Piedmont. Soybean [Glycine max (L.) Merr.] yields from severely eroded sites in these soils are about half of those from slightly eroded sites. Most of the severely eroded sites are on the Pacolet soil series (clayey kaolinitic, thermic, Typic Kanhapludult), which is shallower to the bottom of the Bt horizon. Differences in infiltration rates may cause these differences in yield. Our objectives were to quantify infiltration rate differences between Cecil and Pacolet soils and to determine the reason for the differences. Infiltration rate was measured using a cylinder infiltrometer at five sites with adjacent Cecil and Pacolet soils, and using a sprinkler infiltrometer at one site. Steady‐state infiltration in the Pacolet was significantly lower than in the Cecil, 4.2 and 30.1 mm h−1, respectively. Cecil infiltration rates increased as depth to the Bt horizon increased. On Cecil, final sprinkler infiltration rate was 61.1 mm h−1 with a sod surface, but surface sealing reduced infiltration with a bare surface to 3.6 mm h−1 within 1 h. The final sprinkler‐infiltration rates of the Pacolet soil were 4.5 mm h−1 for sod and 4.2 mm h−1 for bare surfaces. Pacolet infiltration rates were controlled by the Bt1 layer, which had a lower, saturated hydraulic conductivity (2.3 mm h−1) and fewer mesopores than adjacent horizons but was similar to the upper Bt of the Cecil soil. The Cecil soil's limiting Bt1 horizon occurred much deeper in the profile and had less effect on infiltration. Areas of Pacolet within the Cecil landscape, too small to map separately, can cause increased runoff and variability of yield potential of areas mapped as Cecil.
Tillage and Crop Rotation Effect on Characteristics of a Sandy Surface Soil
Authors: Bruce R. R. , Langdale G. W. , Dillard A. L. 
Published: July 2010

AbstractIn a thermic udic region, a summer crop species may be planted with or without tillage subsequent to a winter grain crop that was planted into a prepared seedbed. This study was conducted to identify the effect of tillage intensity associated with soybean [Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench] crop sequences following winter wheat (Triticum aestivum L.), and the effect of summer crop species on selected physical characteristics of a Cecil sandy loam (clayey, kaolinitic, thermic Typic Kanhapludult). Through eight seasons, soybean and grain sorghum were grown in 10 crop sequences that were imposed on three tillage treatments: conventional tillage (CT), in‐row chisel (MT), and no‐tillage (NT). Following summer crop harvest in the eighth season, aggregate stability, organic C, bulk density, air‐filled pore space, particle‐size distribution, and infiltration of water were measured. Aggregate stability at 0 to 10 mm was significantly higher for MT and NT than for CT. The CT treatment exhibited significantly lower bulk density and higher air‐filled pore space than MT and NT. Infiltration was significantly greater on the MT than the CT and NT treatments. Greater aggregate stability, higher air‐filled pore space, and lower bulk density were measured after two or more years of grain sorghum than after soybean. The maintenance of wheat straw on the soil surface under the MT and NT treatment exhibited an effect to a depth of 75 mm and the in‐row chisel treatment affected infiltration. Crop‐rotational effects can be erased or modified by tillage and may only be observed under NT. Grain yield response of soybean and grain sorghum to changes in soil physical characteristics, as a consequence of crop sequence and tillage, may need to be interpreted in relation to crop species and cropping sequence.
Aluminum and Organic Matter Mobilization from Forest Soil Infiltrated with Acidified Calcium Sulfate Solutions
Authors: Berry Duane F. , Zelazny Lucian W. , Walker Hubert L. 
Published: July 2010

AbstractInvestigations of acid rain effects on forest soils have generally overlooked Ca, a major component of precipitation. This study was conducted to determine the effects of Ca on the mobilization of Al and organic matter in a Cecil soil (clayey, kaolinitic, thermic Typic Kanhapludult). Acidic solutions (pH 4.2) containing ambient or near‐ambient precipitation concentrations of Ca, K, and SO4 were used to infiltrate columns containing Oa, EB, or Oa/EB bihorizon soil material. Leachate was analyzed for dissolved organic carbon (DOC), Al, Ca, K, and H ions. A net release of protons was observed when the Oa surface horizon was infiltrated with 0.05 mol m−3 CaSO4 or 0.25 mol m−3 CaSO4 or K2SO4 leaching solutions, but not 0.05 mol m−3 K2SO4 solution. Infiltration of Oa horizon soil with Ca solutions resulted in release of more protons than with K solutions of comparable ionic strength. Calcium leaching solutions were also more effective than K solutions (7.7% and 28% for 0.05 and 0.25 mol m−3 solutions, respectively) in mobilizing Al from Oa/EB bihorizon soils. These differences were not found in EB horizon soils treated with the same leaching solutions. Our results suggest that CaSO4 leaching solutions, at concentration levels consistent with those in precipitation, displaced protons from the Oa horizon, which subsequently infiltrated the underlying EB horizon causing increased solubilization of Al. While some Al was undoubtedly associated with organic matter, overall, movements of Al and organic matter in Oa/EB bihorizon soil columns were found to be independent of one another.
Phosphorus and Aluminum Release from a Spodic Horizon Mediated by Organic Acids
Authors: Fox T. R. , Comerford N. B. , McFee W. W. 
Published: July 2010

AbstractThe ability of organic acids to affect surface and solution reactions of P and Al in soils containing Al‐oxide surfaces is related to their ability to form stable complexes with Al. This study was conducted to determine if the amount of P and Al released following the addition of an organic acid to a Bh horizon soil could be estimated based on the Al stability constant (logKAl) of the organic acid. The release of Al and inorganic P from spodic horizon material increased in the presence of organic acids that form stable complexes with Al. Overall, the logKAl value was a good indicator of the effect of the organic acid on inorganic P and Al release. Among the 16 organic acids studied, release of Al and inorganic P increased exponentially with increasing stability constants. A threshold value of approximately 4.1, however, was required before substantial amounts of inorganic P were released. This value may reflect the stability of P bond to Al‐oxide surfaces in this soil. Salicylic acid was a notable exception to the observed trend in release of both Al and P; despite a large stability constant, little inorganic P or Al was released. Although significant amounts of soluble organic P were released in all the organic‐acid solutions, the amount of soluble organic P released was not related to the stability constant of the organic acids.
Sampling the Atmospheres of Small Vessels
Authors: Breitenbeck G. A. 
Published: July 2010

AbstractGas‐tight syringes and other gas sampling devices are not entirely satisfactory for use in many studies of soil processes requiring precise repeated sampling of the atmospheres of glass bottles and other incubation vessels. This report describes the construction and use of a gas‐sampling apparatus that permits accurate, precise analyses of headspace gases contained in sealed vessels. The sampling apparatus consists of a 10‐port gas‐sampling valve fitted with a syringe used to fill a sampling loop with a representative sample of the atmosphere contained in the headspace of an incubation vessel. A supply of inert gas purges the apparatus between samples. Use of this technique is appropriate in experiments where repeated analyses of sample vessels are performed, because sampling removes a minimum of gas in excess of that used for analysis and does not appreciably alter the pressure within the vessel. Because the effects of previous sampling on headspace concentrations are calculated, small vessels can be repeatedly sampled with precision. The apparatus is easily assembled from readily available components.
Spatial Scale Dependence of In Situ Solute Transport
Authors: Van Wesenbeeck I. J. , Kachanoski R. G. 
Published: July 2010

AbstractIn field solute‐transport experiments, two spatial scales of the continuum of the dispersion process have been measured: local scale and field scale. The objective of this experiment was to develop a method for measuring in situ the transition from the local scale to the field scale during unsaturated flow conditions. The spatial variability of in situ solute dispersion was examined in two field sites. Soil‐solution samplers were installed in a transect at a 0.4‐m depth and 0.2‐m spacing in both a cultivated and never‐cultivated (forested) site. A pulse of KCl was applied to both sites under conditions of constant surface flux density of water, which was applied using a trickle irrigation system. The variance of solute travel time, V2(t), at different spatial scales was calculated from moment analysis of breakthrough curves (BTC) obtained by averaging local BTC across different spatial scales. The scale dependence of V2(t) indicated scales of at least 2.8 and 3.8 m were needed to reach an effective far field variance for the forested and cultivated sites, respectively. The larger scale in the cultivated site was due to an increase in horizontal correlation length scales of soil properties caused by tillage mixing. The scale dependence of V2(t) can be used to determine the minimum plot size necessary to include all major horizontal variations in solute travel time, which can then be compared with spatial distributions of soil properties affecting transport.
Construction of Isolinear Maps of Soil Attributes with Empirical Confidence Limits
Authors: Bregt A. K. , Wopereis M. C. S. , McBratney A. B. 
Published: July 2010

AbstractMoisture‐deficit data were obtained at 398 point locations in the Mander area in the Netherlands by simulation using soil‐profile attributes. From this data set, a test subset of 75 points was selected at random. The test set was used to select the best of four prediction procedures: ordinary and universal kriging with the original data set, and ordinary and universal kriging with a log‐transformed data set. The mean square error of prediction (MSEP) was used to evaluate prediction quality. The lowest MSEP of prediction was obtained using ordinary kriging of the untransformed data. Ordinary kriging was then used to predict moisture deficits and estimate their associated kriging variances at points on a 50 by 50 m grid. The average ratio of actual square errors of prediction to the estimated kriging variances at the 75 test locations was used to adjust the kriging variance estimates on the regular grid to get more realistic estimates. These empirically derived, more realistic estimated kriging variances were then used to construct an isolinear map of moisture deficit with confidence limits. The resulting map showed that, in most of the region under study, the 90% confidence interval for moisture deficit contains 15 mm. This type of map allows the user to obtain confidence limits as well as the predicted value for any point on the map.
Pretreatment Effect on Dispersion of Carbonates in Calcareous Soils
Authors: Hartwig R. C. , Loeppert R. H. 
Published: July 2010

AbstractA pH‐stat procedure was previously developed to determine the effective particle‐size distribution of soil carbonates. The results obtained by the pH‐stat procedure are influenced by the accessibility of carbonate surface sites to the titrant and, therefore, provide a methodology for the comparison of carbonate dispersion treatments. In this study, the influence of dispersion treatment on the determination of effective particle‐size distribution of soil carbonates was examined. The treatments consisted of agitation, sonication, or Na saturation of clay cation‐exchange sites of calcareous soils representing three series (Austin: fine‐silty, carbonatic, thermic Entic Haplustoll; Rio Grande: coarse‐silty, mixed (calcareous), hyperthermic Typic Ustifluvent; Victoria: fine, montmorillonitic, hyperthermic Udic Pellustert). Shaking and sonication pretreatments resulted in increases in the experimentally determined proportion of effective fine‐clay size soil carbonates and corresponding decreases in the effective silt‐ and sand‐size carbonates, when compared with the untreated soils. As the intensity of either of these pretreatments was increased, the proportion of effective clay‐size carbonates increased. Scanning electron microscopy indicated that the longer and more intense sonication treatments resulted in a higher degree of disruption or grinding of carbonate aggregates. Sodium saturation of the clay cation‐exchange sites resulted in the most effective disaggregation of the phyllosilicate‐carbonate complex, as indicated by the greatest proportion of effective clay‐size and lowest proportions of effective silt‐ and sand‐size carbonates. Sodium saturation may also result in a lower degree of disruption of carbonate particles or carbonate‐cemented aggregates than may occur with intense sonication. An initial Na saturation is, therefore, recommended as a pretreatment for the determination of effective particle‐size distribution of soil carbonates.
Humic and Fulvic Acid Adsorption by Silicon and Aluminum Oxide Surfaces on Clay Minerals
Authors: Schulthess C. P. , Huang C. P. 
Published: July 2010

AbstractNatural (untreated) clays are most probably amorphous on their outermost surface layers due to the continuous and natural process of partial dissolution and reprecipitation of the clay components at the solid‐aqueous interface. The pH‐dependent adsorption on Al and Si oxides, mordenite, kaolinite, and montmorillonite of a humic acid (HA) and a fulvic acid (FA) was described as occurring on Al and Si sites. The surfaces of the clay minerals were modeled as mixtures of amorphous Al and Si oxides. The results showed a strong adsorption of the organics by the Al sites on the Al oxide and kaolinite, and a weak adsorption of organics by the Si sites on the Si oxide, mordenite, and montmorillonite. At low pH values, the Si sites on the Si oxide, mordenite, and montmorillonite adsorbed FA; these latter observations strongly suggest that the adsorption of FA by the interplanar spaces of expanding clays is driven by forces that can be studied using amorphous Si oxide as the adsorbent. Multivalent cations will form organo‐metallic complexes that significantly increase adsorption, particularly on Si sites; exceptions were found with some FA‐metal complexes, which were attributed to the degree of complexation. The implication of these observations is that, in natural systems, the adsorption of aqueous compounds is highly dependent on the type of (amorphous) surface present at the outermost layer of the solid phase in contact with the liquid phase.
Competitive Adsorption of Phosphate and Oxalate by Aluminum Oxides
Authors: Violante A. , Colombo C. , Buondonno A. 
Published: July 2010

AbstractThe aim of this work was to study: (i) the competitive adsorption of phosphate (P) and oxalate (OX) anions on an Al oxide as influenced by pH and order of anion addition; and (ii) the adsorption of P on and the desorption of OX from an Al precipitation product [Al(OH)x‐OX] formed in the presence of OX ions. The amount of P adsorbed on Al oxide in the absence of OX decreased with increasing pH. In the absence of P, OX adsorption exhibited a broad maximum between pH 5.0 and 7.0, but rapidly decreased at a pH <5.0 or >7.0. The order of anion addition strongly influenced the adsorption of both P and OX. Maximum reduction in P adsorption occurred when OX was introduced before P, whereas reduction was negligible when P was added before OX. The efficiency of OX in reducing P adsorption was relatively high at acidic pH values, but it was poor at a pH >7.0. The presence of P strongly depressed OX adsorption when P was added before OX or when the anions were added together. The efficiency of P in reducing OX adsorption increased with increasing pH. Finally, the ability of P in replacing OX ions from Al(OH)x‐OX was poor at pH values <7.0, but increased in alkaline environments with increasing pH. The data thus reveal that OX ions compete strongly with P for adsorption sites of Al oxides when they are added before the inorganic ions or are coprecipitated with Al in Al precipitation products, and mainly at acidic or neutral pH values.
Effect of Sulfur Source on Sulfur Oxidation
Authors: Lindemann W. C. , Aburto J. J. , Haffner W. M. , Bono A. A. 
Published: July 2010

AbstractThe rate of elemental sulfur (So) oxidation in soils may be affected by the source of So. This study was conducted to determine the effect of So source on So oxidation. Liquid culture studies with Thiobacillus thiooxidans and T. thioparus, laboratory incubations with a Holloman soil (loamy, gypsic, thermic, shallow Typic Torriorthent) and a Belen soil (clayey over loamy, montmorillonitic [calcareous], thermic Typic Torrifluvent), and a field study on the Belen soil were conducted. Periodic measurements included pH as a measure of So oxidation to H2SO4, electrical conductivity (EC) as a measure of dissolution of CaCO3 from H2SO4 production, and available Fe, Zn, P, and SO4 at the end of soil experiments as a measure of So‐oxidation effects on nutrient availability. The So sources included pure So (Sp), Wettable S (Sw), flowable So (Sf), and Disper‐Sul So (Sd). In liquid culture, Sw, Sf, and Sd inhibited or slowed So oxidation, compared with Sp, suggesting an ingredient of the commercial So sources was responsible for oxidation inhibition. Oxidation of Sw, Sf, and Sd were similar to Sp oxidation in laboratory soil incubations and in the field. Results indicate that the So source is not the cause of slow So oxidation in some New Mexico soils. Chemoautotrophic So oxidizers were present in unamended soils and their numbers increased in So‐amended soils. Although So amendment (25 g So kg−1) in the field decreased pH approximately 0.5 unit and increased SO4 tenfold, So amendment did not increase available Fe, Zn, or P. The slow rate of So oxidation in some New Mexico soils and failure of So amendment to increase nutrient levels are attributed to the buffering capacity of the calcareous soils.
Chemical Structural Studies of Forest Soil Humic Acids: Aromatic Carbon Fraction
Authors: Kögel‐Knabner Ingrid , Zech Wolfgang , Hatcher Patrick G. 
Published: July 2010

AbstractForest soil organic matter contains about 20 to 30% aromatic carbon moieties. In order to follow the changes in the structural composition of the aromatic C during humification a combination of cross‐polarization magic‐angle spinning (CPMAS) 13C nuclear magnetic resonance (NMR) spectroscopy and CuO‐oxidation was used. Humic acids were extracted from the forest floor, A, and B horizons of a forested Typic Dystrochrept, an Entic Haplorthod, and a Lithic Udorthent. The materials collected differ in the degree of humification, from fresh litter material to humified mineral soil horizons, as determined by macromorphological observation. The humic acid fraction isolated from fresh litter of European beech (Fagus silvatica L.) and Norway spruce (Picea abies Karst) shows mainly peaks attributable to aromatic C derived from lignin and tannin structures, which are both partly extractable by alkaline solvents. The most prominent feature of the NMR spectra is the decrease of phenolic and methoxyl C with increasing degree of humification, accompanied by decreasing yields of lignin‐derived CuO‐oxidation products. Simultaneously, the signal intensity at 130 ppm in the 13C‐NMR spectra increased. Detailed structural assignments for this signal can be obtained by measuring the percentage of signal intensity from protonated and nonprotonated C by dipolar dephasing 13C‐NMR spectroscopy. The percentage of nonprotonated aromatic C, and more specifically the C‐substituted aromatic C fraction, increase when humification proceeds. Assuming that lignin is the primary precursor of the aromatic C components of humic acids in forest soils, then the lignin structure is altered considerably during humification, resulting in lignin‐derived aromatic structures with a high degree of C substitution and carboxyl functionality.
Drilling Method for Collection of Undisturbed Soil Monoliths
Authors: Persson L. , Bergström L. 
Published: July 2010

AbstractIn studies of water and solute movement in soils, use of undisturbed monoliths is usually preferred. A drilling technique to collect such monoliths (0.295 m i.d.; 1.0, 0.5, or 0.3 m in length) with minimal soil disturbance was developed. The drill consists of a steel cylinder with four mounted cutting teeth at the bottom, into which a plastic casing is inserted. The drill‐cylinder rotates around the casing and carves out a soil core that is gently pushed into the casing using only a minimum of hydraulic pressure. The technique has been used in a wide variety of research applications within soil science, including the measurement of hydraulic properties, soil evaporation, and soil aeration studies. Here, one application is described in which the monoliths were used as field lysimeters planted with either barley (Hordeum vulgare L.) or meadow fescue (Festuca pratensis Hudson). During a 6‐mo period, the grass lysimeters had a much lower total drainage (106 compared with 213 mm for barley) and also lower mean NO3 concentrations in the drainage water (<0.1 compared with 9.3 mg N L−1). The uniformity of response among the replicates and large differences between the two treatments was taken as indirect evidence that sidewall flows were of little significance when using this technique.