bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct Measurement of Denitrification Loss from Soils: II. Development and Application of Field Methods
Authors: Ryden J. C. , Lund L. J. , Letey J. , Focht D. D. 
Published: July 2010

AbstractA method was developed for the direct measurement of denitrification N loss from field soils. The method was based on the observation that in the presence of acetylene (C2H2) concentrations of 0.1 to 5.0% (vol/vol) the sole product of denitrification in soils was nitrous oxide (N2O). Sustained C2H2 concentrations of approximately 0.4 to 1.6% were induced in the atmosphere of a field soil by supplying C2H2 through probes inserted into the soil to a depth of 1 m. The time required to establish these C2H2 concentrations ranged from 15 to 30 min. The concentrations could be maintained for at least 17 hours during which C2H2 was supplied at 2.8 liters/hour. Essentially, no increase in 30N2 concentration was detected under closed soil covers installed at C2H2‐treated field locations which had received 15N‐NO3. At locations without C2H2 treatment an average 30N2 enrichment of 14.2% relative to air was observed. Production of 15N‐labeled N2O and N2 at locations with and without C2H2 treatment was very similar, and essentially 100% of the 15N evolved at C2H2‐treated locations appeared as N2O. Direct measurements of N2O fluxes from an irrigated, fertilized Haploxeroll at locations with and without C2H2 treatment were made using a previously established method. Net denitrification N fluxes, measured as N2O flux from C2H2‐treated locations ranged from 0.5 to 80 g N/ha per hour. Peak N fluxes were between 30 and 80 g N/ha per hour and usually occurred 30 to 60 hours after irrigation had ceased. Total denitrification loss during 123 days was 51.2 kg N/ha with the total fertilizer application being 335 kg N/ha. Dinitrogen/nitrous oxide ratios, determined from the difference in N2O evolution at sites with and without C2H2 treatment, ranged from 0 to 1 during the first 12 to 24 hours of each denitrification cycle after which the ratio gradually increased to values of 10 to 20 towards the end of each cycle. The average value was between 5.6 and 7.4. The methodology provides a technique for direct monitoring of denitrification N loss in situ.
The Effect of Extractable Aluminum, Iron, and Silicon on Strength and Bonding of Fragipans of Northeastern Ohio
Authors: Hallmark C. T. , Smeck N. E. 
Published: July 2010

AbstractPyrophosphate, oxalate, and HCl‐acetylacetone extractions for Al, Fe, and Si were made on five soils with fragipans (Aeric Fragiaqualfs and an Aquic Fragiudalf) and two soils without fragipans (Aeric Ochraqualfs) from Ohio to evaluate the role of amorphous components in effecting bonding between soil particles of fragipans. The distribution of Al extractable in HCl‐acetylacetone was found to coincide with the position of the fragipan and correlated positively at the 0.01 level with rupture strengths which are indicative of fragipan development. Rupture strengths of soil disks from fragipans were shown to decrease following treatment with HCl‐acetylacetone as compared to water treatment alone confirming the removal of a bonding phase in the fragipan by HCl‐acetylacetone. Although a number of features of fragipans are inherited from the parent material, evidence suggests precipitation of an amorphous phase at contact points between soil particles which imparts strength and brittleness observed in fragipans.
Soil Changes Resulting From Long‐term Management Practices in Western Nigeria
Authors: Aina P. O. 
Published: July 2010

AbstractTwo soils at the University of Ife (Nigeria) research farm were evaluated for their physical and chemical properties under long‐term pasture, bush fallow, and arable cultivation that involved three tillage techniques and two fertility levels. The cultivated plots were adjacent to the fallow plots, which were at least 1/2 ha in size. Differences in soil properties between fallow and cultivated soils were considered to be due to soil changes resulting from continuous cropping.The percentage of water stable aggregates (> 2.36 mm) in the 0‐ to 15‐cm soil depth was highest and more stable under fallow than under bush. Stability values were 95 and 80%, respectively, under grass and bush. About 76% and 80% of these aggregates were destroyed after 5 years of continuous cropping, and 88% after 10 years. Aggregate stability of the cultivated soils ranged from one‐fifth to one‐third those of fallow soils. The average bulk densities were 1.24 and 1.52 g/cm3 for fallow and cultivated soils, respectively, while the reductions in porosity and saturated hydraulic conductivity were more than proportionate to the increases in bulk density of the cultivated soils. The fallow soils were about four‐times higher in organic matter than the cultivated soils, which had an average organic matter content of 0.8%. The fallow soils were also higher in nitrate‐nitrogen, exchangeable bases, and CEC than the cultivated soils.Soil deterioration in decreasing order was: Plow‐disk‐harrow > plow > no‐tilage. Fertilizer treatments had no efect on soil deterioration after 10 years of continuous cropping.
A Rupture Technique to Determine Fragipan Strength
Authors: Hallmark C. T. , Smeck N. E. 
Published: July 2010

AbstractA method is presented to evaluate the strength of fragipans based upon the rupture of 1.2 cm thick disks cut from air dry soil cores. Rupture values abruptly increase in the fragipan as compared to overlying horizons and decrease with depth in the lower B3 and C horizons. Rupture strength measurements may prove valuable in objectively assessing fragipan development and its subsequent influence on water movement and root penetration.
The Mitigating Effect of Residual Fertilizer Copper on the Decomposition of an Organic Soil in Situ
Authors: Mathur S. P. , Hamilton H. A. , Levesque M. P. 
Published: July 2010

AbstractThe recently reported inhibitory effect of Cu on the in vitro decomposition of some organic soils was examined under field conditions.The 2‐ha field studied has been cultivated for 45 years Within this field, the extent of humification, and pH vary little among the 114 sites examined. Since Cu was applied for the last 15 years almost exclusively to a distinct area along the short axis of the field, total and extractable Cu contents were found to decrease twofold from this band to the remainder of the field. Evolution of CO2 from 15 sites on this field was found to carry 16 to 52 g of C from each square meter of soil surface in a period of 40 days in summer. Carbon loss from this field did not correlate significantly with soil moisture or ash contents. The rate of CO2 evolution, however, significantly (1% level) negatively correlated with both the total and extractable Cu contents. Acid phosphatase activity also fell sharply as Cu content increased. The possibility of using Cu (<100 kg/ha) for mitigating the subsidence of some organic soils is discussed.
Calculation of Saturated Hydraulic Conductivity of Some Pedal Clay Soils Using Micromorphometric Data
Authors: Bouma J. , Jongerius A. , Schoonderbeek D. 
Published: July 2010

AbstractThe saturated hydraulic conductivity (Ksat) was calculated for undisturbed freeze‐dried samples of seven clay soils, by using micromorphometric Quantimet data. Voids were characterized in terms of quantity (number and length), type and directly measured size. Methylene blue was used to indicate flow patterns. A statistical planar and tubular void‐interaction model was used to estimate sizes of “necks” in the flow system, which were assumed to determine Ksat. Measured Ksat values were within the calculated Ksat range, when relatively large, vertically continuous tubular voids were not present. Very small variations of the width of planar “necks” had a strong effect on the magnitude of Ksat. Soil which was moist when sampled had larger planar “necks” and higher Ksat values than soil which had been in wet condition for several months. This difference was attributed to the effects of soil swelling. In general, volumetric percentages of active (stained) voids (estimated by % surface area) were <1. This illustrates the basic difficulty of estimating Ksat in clay soils by methods which use relative volumes of voids.
Nitrate Leaching in a Sludge‐Treated Forest Soil
Authors: Sidle R. C. , Kardos L. T. 
Published: July 2010

AbstractAnaerobically digested liquid sludge was applied during two separate periods to plots in a mixed hardwood forest. High treatment plots received 26.96 metric tons/ha total solids and 3,034 kg/ha N loadings during the two applications, and low treatment plots received approximately half these loadings. Percolate samples collected at the 15‐cm depth contained a maximum of 290 mg/liter NO3‐‐N in the high treatment and 194 mg/liter NO3‐‐N in the low treatment. Maximum monthly levels of NO3‐‐N in percolate sampled at the 120‐cm depth lagged 6 months behind peak levels at the 15‐cm depth. Calculated average active transmitting soil porosity (Pact), based on field water budget data over this 6‐month period, ranged from 15 to 22%. A CSMP computer simulation model based on a solution to the convection diffusion equation estimated the average Pact to be 15%. Since these data indicate that 27 to 50% of the pores may be stagnant, this suggests that soluble NO3‐‐N was being channeled through interconnected macropores in the soil profile.
Comparative Effectiveness of Fourteen Solutions for Extracting Arsenic from Four Western New York Soils
Authors: Johnston Steven E. , Barnard Walther M. 
Published: July 2010

AbstractFour western New York soils differing in soil type and land use were subjected to (i) extraction of As by 14 solutions for soil‐solvent mixtures shaken for 1, 3, 7, and 18 hours; (ii) a sequential extraction with solvents designed to identify water soluble‐As (Ws‐As) and As associated with Al (Al‐As), Fe (Fe‐As), and Ca (Ca‐As); and (iii) a hot HNO3‐H2SO4 digestion to determine “total” As. Arsenic was determined by atomic absorption spectrophotometry employing arsine generation.In each soil sample the sequential extraction demonstrated that Fe‐As >> Ca‐As > Al‐As > Ws‐As; the total amount removed by the sequential extraction was only 34 to 41% of the total As in three low As (15.0 to 16.4 µg/g As) soil samples and 98% in a lead arsenate‐sprayed orchard sample containing 52.1 µg/g As.Deionized distilled water, 1N NH4Cl, and 0.5M solutions of CH3COONH4 (“NH4Ac”), NH4NO3, and (NH4)2CO3 generally removed < 0.1 µg/g As from the soils. For the more effective solvents, the amount of As extracted increased with shaking time but an 18‐hour shake never exceeded 80% of that extracted sequentially for any sample. The relative effectiveness of the basic solutions in removing As was in the order of 0.5M NH4F ≈ 0.5M NaHCO3 < 0.5M (NH4)2CO3 < 0.5M Na2CO3 < 0.1M NaOH; for acid solutions the order was 0.05N HCl + 0.025N H2SO4 ≈ 0.5M HCl < 0.5M KH2PO4 < 0.5N H2SO4.Arsenic extraction data obtained in this study are consistent with the view that P and As react similarly in solutions containing acetate, sulfate, fluoride, bicarbonate, hydroxide, and hydrogen ions.
Water‐Dispersible Soil Organic‐Mineral Particles: I. Carbon and Nitrogen Distribution
Authors: Young J. L. , Spycher G. 
Published: July 2010

AbstractWater‐dispersible particles from six epipedons and one Bh horizon representing six different soil orders were separated into sand, silt, and clay particles, and the clay‐organic particles were further fractionated by density. Organic C and N concentrations were lowest in sand, intermediate in silt, and highest in clay, but exceptions to this trend were observed and accounted for. Light clay‐size, organo‐mineral particles had (i) high levels of sorbed organic C; (ii) wide C/N ratios; and (iii) low amounts of alkali‐extractable C. The reverse was true for heavy clay‐size particles. A continuum of particle compositions existed between the density extremes which differ for different soils. The heterogeneity of clay‐size particles can be explained in terms of their position within the soil fabric: Light particles evolve at the surfaces of (micro‐) aggregates and are exposed to the soil biosphere, whereas heavy particles occupy intra‐aggregate space shielded from the soil biosphere.
A Simple Textural Index for Assessing Chemical Weathering in Soils
Authors: Torrent Jose , Nettleton W. D. 
Published: July 2010

AbstractChemical weathering affects the particle size distribution of soils, but little use has been made of this fact other than the inferences of increased chemical weathering generally made from increase in clay content. We postulated a simple model for assessing chemical weathering from particle size distribution. In the model, we assumed that a rind tends to peel‐off a mineral when the mineral is under attack by an advancing weathering front parallel to its surface. Using the model, we calculated theoretical particle size variations of some loessial soils. The calculations, as expected, showed that fine fractions (< 50 µm) are much more affected by chemical weathering than are coarse fractions (> 50 µm). We concluded from this that silt fractions may be used for assessing chemical weathering, but if they must be used for assessing uniformity of parent material, they should be used advisedly.We applied our model to 161 loessial soils of the Mississippi Valley, all having udic or aquic moisture regimes. We used the fine‐silt/total‐silt ratio trend for the upper part of the solum as a weathering index. The index correlates with mean annual temperature (r = 0.70) which in humid regions is assumed to be the main factor involved in the chemical weathering of soils. Although our index is not universally applicable, it may help in comparing the weathering status of soils developed on similar parent materials.
Irrigation Water Conservation Using Wide‐spaced Furrows
Authors: Stone J. F. , Garton J. E. , Webb B. B. , Reeves H. E. , Keflemariam J. 
Published: July 2010

AbstractFurrow irrigation studies comparing water applications to narrow and wide‐spaced furrows were conducted on three crops at thee locations in Oklahoma over eight growing seasons. Wide‐spaced‐furrow irrigation usually required about half the water of narrow spacing. In 9 of 11 studies, no yield reductions were noted. In the seasons where yield reductions were noted, the atmospheric evaporative demand was high. A simple test was devised to indicate if a season in progress shows high atmospheric demand. The evaporative demand test involves measurement of rainfall and daily wind movement. Using standard National Weather Service instruments, daily average of rain > 1.6 mm between 15 July and 31 Aug. combined with daily wind movement < 155 km in August caused no yield reduction in wide‐spaced‐furrow irrigation. Wind was measured at the standard height of a “Class A” evaporation pan (51 cm). Conservation of water from wide‐spaced‐furrow irrigation should be possible on medium to fine textured soils in many semiarid regions of the world.
Carbon Cycling During Sewage Sludge Decomposition in Soils
Authors: Terry R. E. , Nelson D. W. , Sommers L. E. 
Published: July 2010

AbstractThe objectives of this study were to determine the extent and kinetics of sludge decomposition in soil, to evaluate the effects of sludge addition on microbial degradation of soil organic matter, and to determine the distribution of residual sludge organic C in soil organic matter fractions. Synthetic sewage sludge was prepared by anaerobically digesting a mixture of 14C‐labelled Candida utilis cells and inorganic salts. The prepared sludge had a composition which was similar to that of many anaerobically‐digested municipal sludges. Synthetic sludge was added to soils and 14CO3 activity and CO2 production were measured periodically during 336 days of incubation. At the end of incubation, the distribution of residual 14C in soil organic matter fractions was determined. Sludge decomposition was rapid during the first 28 days of incubation and then decreased to a slower, nearly constant rate for the remainder of the period. At the end of 336 days of incubation, 46% of synthetic sludge organic 14C was evolved as CO2. In comparison, 26 to 42% of added organic C was apparently evolved as CO2 from soils treated with municipal sludges and incubated for 130 days. These findings suggest that a fraction of anaerobically‐digested sludge was readily decompossible when added to an aerobic soil; however, the major portion of sludge organic matter (55 to 80%) was resistant to decomposition. There was a linear relationship between cumulative 14CO2 evolution and the log of incubation time. From this relationship the turnover time of synthetic sludge in soil was calculated to range from 343 to 890 years. Decomposition of sludge in soil increased the degradation of native soil organic matter by approximately 100% over a period of 336 days. At the end of 168 days of incubation, 62% of the residual sludge organic 14C added in sludge was recovered from soils as humic and fulvic acids.
Soil‐Landscape Relationships of the Tidal Marshes of Maryland
Authors: Darmody R. G. , Foss J. E. 
Published: July 2010

AbstractA study was conducted to investigate and model the soil‐landscape relationships represented in the 87,000 ha of tidal marsh in Maryland. Models are presented for three physiographic marsh landscapes: Coastal, Estuarine, and Submerged Upland. Coastal marshes, about 8% of the total marsh area, have formed in the lagoons behind coastal barrier islands. The associated soils are primarily Sulfaquents and Sulfihemists. Estuarine marshes, 38% of the total, have formed from recent accumulation of sediments in stream channels and estuarine meanders. The majority of the associated soils are Sulfaquents, Sulfihemists, and Hydraquents. Submerged Upland marshes are the most extensive, covering an estimated 54% of the total. These marshes have formed as a result of the inundation of low‐lying uplands by rising sea level. It appears that the soils were formerly Aquults and, because of submergence, they have become Histic Halaqualfs (proposed) and Sulfihemists.
Physical, Chemical, and Mineralogical Characteristics of Soils from Volcanic Ash in Northern Idaho: I. Morphology and Genesis
Authors: Fosberg M. A. , Falen A. L. , Jones J. P. , Singh B. B. 
Published: July 2010

AbstractMission soils, coarse‐silty, mixed, frigid Andic Fragiochrepts, are representative of volcanic ash soils found extensively in northern Idaho, northeastern Washington, and northwestern Montana. They have developed under a western hemlock (Tusuga heterophylla) habitat type with 740 mm of precipitation, > 8°C mean summer soil temperature and 7.5°C mean annual soil temperature (weather data, Univ. of Idaho. Res. Stn., Sandpoint). The B2ir or cambic horizons have developed from volcanic ash and the underlying IIA'&B' and IIB'2x horizons have fragipans developed in glacial outwash sediments. Horizons from volcanic ash have higher values of estimated allophane, organic C, extractable Fe, Al, and Mn, exchangeable H, 1/3‐ and 15‐bar moisture, and CEC than do underlying horizons. Bulk densities range from 0.80 to 0.90 in volcanic ash horizons compared with 1.41 to 1.65 for glacial sediments. X‐ray patterns show little indication of crystalline minerals in the ash‐related horizons. Concretions have greater contents of Mn and Fe whereas Al remains relatively constant in relation to the total soil. Development of a B2ir, without an Al horizon under the O horizon, is characteristic of soils associated with these climatic and vegetational zones. Diagnostic properties make the cambic gradational to a spodic horizon.
Influence of Weed Growth and Tillage Interval During Fallow on Water Storage, Soil Nitrates, and Yield
Authors: Lavake D. E. , Wiese A. F. 
Published: July 2010

AbstractIn an effort to minimize tillage operations and production costs five sweep tillage intervals were evaluated for 7 years during the two 11‐month fallow periods in a winter wheat (Triticum aestivum L. ‘Tascosa’)‐sorghum (Sorghum bicolor (L.) Moench) cropping sequence. The tillage intervals ranged from very short or once every 2 weeks to as long as 24 days after weed emergence. Their effect on soil water storage, soil NO3‐N level and crop yield were determined on Pullman clay loam in the Southern Great Plains.Delaying tillage for 17 and 24 days after weed emergence reduced available soil water in the top 120 cm of soil.Average NOa‐N content in the top 120 cm of soil decreased from over 185 kg/ha with sweep tillage at 2‐week intervals to 56 kg/ha when sweep tillage was delayed until 24 days after weed emergence.Average wheat yields were not reduced when sweep tillage was performed 17 days after weed emergence, however they were reduced when tillage was delayed until 24 days after weed emergence. Average sorghum yields were not reduced when tillage was delayed 10 days after weed emergence. Delaying tillage to 17 days after weed emergence cut sorghum yield. Most farmers till about 4 to 10 days after weed emergence. Delaying tillage as much as possible as indicated in this trial will eliminate on or two tillage operations in an 11‐month fallow period.
Correlation of Soil Plasticity with Amorphous Clay Constituents
Authors: McNabb D. H. 
Published: July 2010

AbstractThe percentage of amorphous constituents removed from the clay size fraction of western Oregon soils by kinetic dissolution was significantly correlated with soil plasticity. Soil plasticity was identified by the plasticity angle which was defined by the angle, relative to the ‘A’ line intercept, where the Atterberg limits of air‐dried soil occurred on the Casagrande plasticity chart. An exponential correlation between the plasticity angle and the sum of the amorphous Al2O3 and SiO2 was more significant than between the plasticity angle and the sum of the amorphous Al2O3, SiO2, and Fe2O3 (r2 = 0.88** and 0.76**, respectively).The Atterberg limits of the soil were not directly correlated with the percentage of amorphous constituents.
A Critical Evaluation of the Extension of Zero Point of Charge (ZPC) Theory to Soil Systems
Authors: Parker J. C. , Zelazny L. W. , Sampath S. , Harris W. G. 
Published: July 2010

AbstractThe points of zero salt effect (PZSE) of surface and subsurface horizons of soils ranging from an Hapludoll to a Paleudult were obtained from batch titrations in CaCl2 solutions with and without prior Ca saturation and in NaCl solutions following Na saturation. PZSE's of Na‐saturated samples equilibrated for 1 hour were generally between pH 2 and 3, while those of Na‐ or Ca‐saturated samples or unwashed samples equilibrated for 2 days were generally between 3 and 4. The effect of equilibration time was attributed to gradual sample decomposition accompanied by conversion of Na‐saturated soil to an Al‐Na‐system.Points of zero net charge (PZNC) were evaluated by measurement of Ca and Cl adsorption at various pH levels. No net charge reversal from negative to positive was found to occur above pH 2.0. This discrepancy between PZSE and PZNC was attributed to specific adsorption of cations, H+ exchange with counterions associated with permanent charge sites and other reactions of H+ or OH‐ which did not result in a change in surface charge. From 30–90% of the H+ or OH‐ lost from solution during titration did not create an equivalent change in surface charge. Exchange reactions and reaction of H+ with Al and Fe in various forms are implicated in this regard. It is suggested that the use of potentiometric titrations for the estimation of electrochemical properties of soils regarded with considerable caution.