bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detachment of Soil Aggregates by Simulated Rainfall
Authors: Mazurak Andrew P. , Mosher Peter N. 
Published: July 2010

AbstractSharpsburg silty clay loam was separated into 11 aggregate fractions with the following diameters: 9,250–4,760µ, 4,760–3,360µ, + … +, 297–210µ, and <210µ. Krilium solution was added to half of each aggregate fraction to make the aggregates more water‐stable. The aggregate fractions were packed into splash‐cups and exposed to simulated rainfall intensities from 2 to 12 cm/hr. Raindrops were 5.1 mm in diameter and fell 11.33 m onto the surface of soil materials. Splash of soil particles and aggregates was caught, oven‐dried, and weighed.The amount of detachment of aggregates was linearly related to the rainfall intensity.Detachment of non‐treated aggregates exposed to rainfall increased from 76 mg of particles per cm3 of water to a maximum amount of 172 mg/cm3 as the aggregate diameters decreased from 9,250–4,760µ to 2,360–1,680µ. Then, the amount of detachment decreased with decreasing diameter to aggregate to 78 mg/cm3 for aggregates < 210µ diameter.The addition of Krilium to aggregates reduced the amount of detachment of aggregates >420µ in diameter exposed to simulated rainfall. The amount of splash increased with decreasing diameter of Krilium treated aggregates until 297–210µ diameter was reached (138 mg/cm3), then it decreased (101 mg/cm3) for aggregates < 210µ diameter.
Glycerol Vapor Adsorption on Clay Minerals and Montmorillonitic Soil Clays
Authors: Moore D. E. , Dixon J. B. 
Published: July 2010

AbstractAdsorption isotherms of glycerol were obtained for clay fractions of montmorillonite, vermiculite, kaolinite, and eight soil clays at 80C in an evacuated system. The weight of glycerol required for monolayer formation was determined by application of the BET equation to adsorption data. Montmorillonite samples gave BET monolayer values from 211 to 230 mg glycerol/g of montmorillonite which is in the theoretical range. Monolayer values calculated for soil montmorillonites from BET monolayer values and corrected for impurities were 209 to 239 mg glycerol/g of montmorillonite in < 0.08µ soil clays. The surface area values estimated from these soil montmorillonite monolayer values range from 738 m2/g to 844 m2/g. Vermiculite gave BET monolayer values of 40 mg and 96 mg/g of clay for 2 to 0.2µ and 0.2 to 0.08µ samples, respectively. This method appears to effectively measure the sorption surface of montmorillonite and indicates lower sorption surface of vermiculite than is suggested by its structural similarity to montmorillonite. Glycerol monolayer values indicate only modest reduction of particle size in < 0.08µ compared to 0.2 to 0.08µ montmorillonite from soil clays and Wyoming bentonite. The success of glycerol adsorption on clays, in spite of a very low vapor pressure, suggests that more volatile polar organic molecules might effectively be studied by adsorption on clay surfaces.
The Influence of Soil Water Matric Potential on the Strength Properties of Unsaturated Soil
Authors: Williams John , Shaykewich C. F. 
Published: July 2010

AbstractA study was made of the contribution that matric potential makes to effective stress and therefore the strength properties of two unsaturated soils. From an evaluation of the effective stress parameters C' and ø', and the unconfined strength, the shear strength, effective stress, and the χ factor were estimated as a function of soil water matric potential over the range −0.59 to −15.1 bars.The strength properties of a Gretna clay increased rapidly with decreasing matric potential. In a Wellwood loam, however, the strength properties remained relatively constant over the range −0.59 to −15.1 bars.The influence of matric potential on the strength properties of an unsaturated soil can be described in terms of the contribution that matric potential makes to the effective stress operating in the soil system. A measure of the proportion of the matric potential operative in the effective stress is given by the χ factor which is related to the degree of saturation. Therefore, the influence that matric potential has on the strength of an unsaturated soil is related to the moisture retention properties of the soil.The implications arising from the contribution that matric potential makes to the strength properties of an unsaturated soil are briefly discussed in terms of soil‐plant relations.
Adsorption of Polysaccharides by Montmorillonite
Authors: Parfitt R. L. , Greenland D. J. 
Published: July 2010

AbstractAmylose and a dextran of MW 2 million were adsorbed by montmorillonite. However, two dextrans of lower MW did not adsorb on montmorillonite. It is suggested that entropy changes arising from changes in configuration of the macromolecules and the association of water molecules with clay and polymer control the adsorption behavior of uncharged polysaccharides. Poly (galacturonic acid) was adsorbed by aluminum montmorillonite but showed negative adsorption on sodium montmorillonite. The uronic acid components of a soil polysaccharide were adsorbed by montmorillonite if aluminum ions or hydroxy aluminum species were present on the clay; neutral sugar components were adsorbed irrespective of the exchangeable cations present or the pH.
Laboratory Determination of Leachable Soil Boron
Authors: Rhoades J. D. , Ingvalson R. D. , Hatcher J. T. 
Published: July 2010

AbstractLaboratory methods are presented for determining the amounts of boron that must be leached from soils to reduce their soluble boron concentrations to nontoxic levels. One method consists of an extraction of a soil sample with a 0.01M mannitol −0.01M CaCl2 solution. The second method consists of dialysis of a soil sample against a boron‐specific resin in the presence of 0.01M CaCl2 solution. Some of the soils studied were observed to “regenerate” toxic levels of soluble boron following reclamation.
Denitrification by Isolated Soil Bacteria Under Various Environmental Conditions
Authors: Bollag J.‐M. , Orcutt Mary Lou , Bollag Brigitte 
Published: July 2010

AbstractNitrate reducing microorganisms were isolated from soil and their denitrifying properties were compared under various environmental conditions. The isolated denitrifiers cultured in a liquid medium under anaerobic conditions responded differently to changing pH, temperature, nitrate or nitrite concentration. Unfavorable growth conditions led to the accumulation of nitrite. Various combinations of the selected bacteria revealed that interactions occur among the microbes during growth in relation to their denitrifying activity. Variation among bacterial species and specific environmental conditions resulted in different denitrifying characteristics; therefore, generalizations cannot be made regarding microbial denitrification in soil for possible applied uses.
Mulch Rates Required for Erosion Control on Steep Slopes
Authors: Meyer L. D. , Wischmeier W. H. , Foster G. R. 
Published: July 2010

AbstractThe erosion‐reducing effectiveness of six rates of straw mulch was tested on slopes averaging 15%. Mulch rates of only 0.56 and 1.12 metric tons/ha reduced soil losses to less than one–third of those from unmulched areas during a series of intense simulated rainstorms. A 2.24‐metric tons/ha rate decreased soil loss to only 18% of that from no mulch, and the 4.48‐ and 8.96‐metric tons/ha rates reduced it to less than 5%.Runoff velocity for the 0.56‐metric tons/ha rate was one‐half that for no mulch, but heavier rates decreased velocity only slightly more. The reduced velocity due to mulching accounted for much of the resulting decrease in soil erosion.Although the small mulch rates greatly reduced erosion, more mulch was required to fully control erosion than was required on the less‐steep, more permeable soil conditions tested in earlier studies.
Measurement of Attenuation of 137Cs and 241Am Gamma Rays for Soil Density and Water Content Determinations
Authors: Corey J. C. , Peterson S. F. , Wakat M. A. 
Published: July 2010

AbstractSoil density and water content can be determined concurrently by measuring the attenuation of two different gamma energies. A dual source containing 241Am and 137Cs was shown to be suitable for these measurements. Multichannel pulse‐height analyzers were evaluated to determine their accuracy under experimental conditions for simultaneous measurements of soil density and water content. NaI(Tl) and Ge(Li) detectors were also evaluated. The measurements were made with a collimated beam, 1 cm in diameter, of 662‐keV gamma rays and 59.6‐keV gamma rays from a source containing 70 mCi of 137Cs and 29 mCi of 241Am. Measured mass attenuation coefficients were 0.08565, 0.07803, and 0.07887 cm2/g for cesium gamma rays and 0.20493, 0.27100, and 0.33480 cm2/g for americium gamma rays with water, Cecil, and Houston Black soil, respectively. The higher resolution of the Ge(Li) detector and a 4096‐channel pulse‐height analyzer had no significant advantage with peaks as widely separated as 662 keV and 59.6 keV. A NaI(Tl) detector and a 400‐channel pulse‐height analyzer were satisfactory. With the multichannel pulse‐height analyzer, it was simpler to adjust the area under the americium peak for the Compton contribution from the cesium radiation than with a single channel pulse‐height analyzer. Water content and density changes in both a swelling and nonswelling soil illustrate the utility of the system.
Measuring Soil Matric Potential in situ by Sensing Heat Dissipation within a Porous Body: II. Experimental Results
Authors: Phene C. J. , Rawlins S. L. , Hoffman G. J. 
Published: July 2010

AbstractA sensor described previously to measure the matric potential of soil water in situ was tested in soil‐plant systems. Experiments were performed in the laboratory in a controlled environment and in the field. In the field, temperatures obtained by the sensor were used to predict optimum time for measurement to avoid error caused by diurnal temperature drift in the soil. The error caused by temperature drift was eliminated completely by using two matched diode sensors and taking a temperature difference measurement.The accuracy of the matric potential sensor proved to be as good as or better than that of other techniques used to measure matric potential. Sensors with high sensitivity in the 0 to −2 bar matric potential range had an accuracy of ±0.2 bar. The accuracy decreased progressively to ±1 bar at a matric potential of −10 bars.
Toxic Metals in Acid Soil: I. Estimation of Plant‐Available Aluminum
Authors: Hoyt Paul B. , Nyborg Marvin 
Published: July 2010

AbstractExchangeable Al and 0.01M CaCl2‐soluble Al were measured in 40 acid surface soils by Clark's procedure for corrected lime potential and exchangeable cations, and by a modified procedure which was developed here. In the modified procedure, 0.01M CaCl2‐soluble Al was extracted by using 16 hr of shaking instead of 5 days, and exchangeable Al was extracted with 1N KCl for 2 min instead of with 2N NaCl for 16 hr. Good agreement was given with the theoretical relationship between corrected lime potential and percent base saturation of the permanent charge sites by both the original and modified procedures. Aluminum extracted by the two procedures and also that extracted by three other methods were then assessed for their availability to plants grown on the soils in a greenhouse study.Criteria of plant‐available Al were the yield responses to liming by barley (Hordeum vulgare L.), turnip rape (Brassica campestris L.), and alfalfa (Medicago sativa L.), and the Al concentration in alfalfa grown on the unlimed soils. Exchangeable Al and 0.01M CaCl2‐soluble Al measured by Clark's and the modified procedures were all closely correlated with the criteria of Al availability. Aluminum extracted by 1N NH4OAc (pH 4.8), 1N NH4OAc (pH 3), or 0.002N HCl methods were not so closely correlated with the criteria.The use of extractable soil Al for the diagnosis of the need for liming is discussed.
Sorption of Inorganic Phosphate by Lake Sediments
Authors: Shukla S. S. , Syers J. K. , Williams J. D. H. , Armstrong D. E. , Harris R. F. 
Published: July 2010

AbstractTwenty‐five sediments from nine soft‐water and five hard‐water Wisconsin lakes sorbed between 20 and 100% of the inorganic P added at a level of 830 µg P/g oven‐dried sediment and between 14 and 99% of that added at a level of 6,700 µg P/g oven‐dried sediment. Noncalcareous sediments usually sorbed more added P than calcareous sediments. P sorption fended to be inversely related to the CaCO3 content of the calcareous sediments. Treatment with oxalate destroyed or virtually eliminated the ability of noncalcareous sediments to sorb added P and greatly reduced that of the calcareous sediments. Oxalate extracted widely varying amounts of Fe (3 to 131 mmoles/100 g) and Al (6 to 26 mmoles/100 g) from the noncalcareous sediments; an appreciable proportion of the total Fe in the noncalcareous sediments was oxalate‐extractable. One noncalcareous sediment, high in oxalate‐extractable Fe, sorbed over 80% of inorganic P added at a level of 16,700 µg P/g oven‐dried sediment. With one exception, two treatments with citrate‐dithionite‐bicarbonate or one oxalate extraction had similar effects on the P‐sorption capacity and released comparable amounts of Fe, suggesting that the extractable Fe is derived from an amorphous iron oxide complex. The proportion of added P sorbed was closely related to the amount of oxalate Fe and to the levels of native total inorganic P in the sediments. It is postulated that a gel complex of hydrated Fe oxide which contains small amounts of Al2O3, Si(OH)4, and organic matter, is the major P‐sorbing component of sediments.
Incorporation of 15N‐Tagged Mineral Nitrogen into Stable Forms of Soil Organic Nitrogen
Authors: Legg J. O. , Chichester F. W. , Stanford G. , DeMar W. H. 
Published: July 2010

AbstractTransformation of 15N‐tagged mineral N into organic forms was accelerated by growing a series of oat crops (Avena sativa L.) in the greenhouse, with each crop growing to sufficient maturity for the seed to be used for the next crop. The plant material was returned to the soil, except for triplicate pots which were removed for analysis at each cropping period. Availability ratios (fraction of plant N that is 15N divided by the fraction of soil N that is initially 15N for each cropping period) declined from an initial value of 10.4 for the Chester surface soil to approximately 2 after 11 crops.During long‐term mineralization tests with soil samples taken after two, five, and eight cropping periods, availability ratios were also stable, or soon became stable, at approximately 2. When similar soil samples were extracted after autoclaving in 0.01M CaCl2 or subjected to acid hydrolysis, however, the “extractability ratios” approached unity. It is hypothesized that about half of the indigenous N in the Chester soil is biologically unavailable because of inaccessibility to microorganisms of organic N compounds or complexes incorporated within microaggregates.
Recovery of Residual Nitrogen by Corn (Zea mays L.) from Various Soil Depths as Measured by 15N Tracer Techniques
Authors: Gass W. B. , Peterson G. A. , Hauck R. D. , Olson R. A. 
Published: July 2010

AbstractA tracer technique was used to evaluate crop recovery of residual inorganic nitrogen from several soil depths. 15N‐labeled nitrate was placed at depths of 9, 60, 120, and 180 cm in field plots planted to corn (Zea mays L.) and containing 409, 468, and 582 kg inorganic N/ha in the 180‐cm profile. Flag leaf samples were collected at three growth stages and their 15N and total N contents determined.At early silk stage, no labeled nitrate was extracted from soil at depths below 120 cm, regardless of residual N level. Nitrate was absorbed at the blister stage from a depth of 180 cm in soil containing the lowest amount of residual N. In soil at the highest level of residual N, little labeled nitrate was recovered at any growth stage at depths below 120 cm. At harvest, more 15N derived from the upper soil profile was found in the stover, while the grain contained considerable 15N obtained from the middle and lower profiles, presumably related to the later period of uptake.
Release of Herbicides from Clay Minerals as a Function of Water Content: I. Kaolinite
Authors: Don Scott H. , Lutz J. F. 
Published: July 2010

AbstractThe influence of water content on the release of six herbicides from kaolinite was studied. Kaolinite suspensions were treated with 14C‐labeled herbicides at rates of 1 and 4 µg/g (based on dry weight of clay). Extracts of the soil solution were obtained at successively increased increments of pressure from 0.3 to 15 bars, using the pressure membrane extractor. The following determinations were made: (i) volume of extract for each pressure‐increment; (ii) concentration of herbicide in the extract, as measured by liquid scintillation; (iii) amount of herbicide remaining, as calculated by difference; and (iv) pH of the extract.The results show that for all herbicides used, except simazine, the concentration in the extracts decreased with increasing pressure increments. The decreases were greatest with diuron and chlorpropham. Simazine concentration was from two to three times greater in the high than in the low‐pressure extracts. High concentrations in low‐pressure extracts suggest that plant availability is high and that movement with water could be a problem with high rainfall under field conditions. Fluometuron and 2,4‐D were negatively adsorbed; the others were positively adsorbed. The order of release in terms of total recovery of herbicide applied at the 1‐ppm rate was: fluometuron > 2,4‐D > atrazine > chlorpropham > simazine > diuron. The order was the same for the 4‐ppm rate except that 2,4‐D was greater than fluometuron. The total recovery of the herbicides in the extracts ranged from 12.0% for diuron to 92.1 for fluometuron.
Effect of Soluble and Exchangeable Aluminum on a Soil Bacillus
Authors: Zwarun A. A. , Bloomfield B. J. , Thomas G. W. 
Published: July 2010

AbstractThe test organism, a Bacillus species isolated from soil, behaved as a typical cation exchanger having a CEC of 95 meq/100‐g organism (oven‐dry weight). Increasing acidity from pH 6.6 to 4.5 greatly reduced the number of surviving cells suspended for 3 hours in an acetate buffer. Addition of soluble aluminum up to 80 ppm produced no further detrimental effect upon the organism, even though the cell walls of the organism were saturated with aluminum. Exchangeable aluminum in the form of Al‐saturated Wyoming bentonite decreased the number of surviving cells as compared with a Ca‐ saturated Wyoming bentonite. Addition of soluble Al to the Al‐clay suspension did not result in any interaction. Upon incubation with the clay suspensions, the organism changed its gram‐staining characteristic. Clay particles in all treatments were adsorbed by the cells producing organism‐clay aggregates.
Extraction of Anions and Cations from Recent Volcanic Ash
Authors: Bornemisza Elemer 
Published: July 2010

AbstractWater extracts of ash from Mt. Arenal, Costa Rica's most recently active volcano, contained up to 32 ppm Ca, 3.3 ppm Mg, 4 ppm K, 4 ppm Na, and 0.4 ppm Mn. No phosphates were extracted by water, but sulfates reached 35 ppm and silicates 1.6 ppm in the extracts. The sample farthest away from the volcano gave extracts of lowest Ca and Mg content. The pH of diluted NaOH suspension of ash decreased on standing by up to 1.5 pH units.
Characterization of Inorganic Phosphate in Noncalcareous Lake Sediments
Authors: Williams J. D. H. , Syers J. K. , Armstrong D. E. , Harris R. F. 
Published: July 2010

AbstractInorganic P added with 0.5M NH4F to noncalcareous sediments was recovered in the NH4F and succeeding 0.1N NaOH extractions. Values of NH4F‐P, corrected on the basis of the recovery of P added with the NH4F reagent, underestimated the total amount of inorganic P capable of interacting with NH4F, but by less than the corresponding uncorrected values. The amounts of inorganic P extracted by 0.5M NH4F followed by 0.1N NaOH, by citrate‐dithionite‐bicarbonate, and by 0.3N NaOH were very similar, the means of the three quantities varying by only 11 ppm. Oxalate‐extractable inorganic P exceeded these quantities by an average of 250 ppm but exceeded the sum of NH4F‐P, 1st NaOH‐P, and reductant‐soluble P by an average of 60 ppm, the difference in the latter comparison being ascribed to the partial or complete dissolution of apatite by the oxalate reagent. Although NH4F‐Al was moderately well correlated with oxalate‐Al (r = 0.70) neither variable was related to NH4F‐P. The very high correlations between NH4F‐P, 1st NaOH‐P, and reductant‐soluble P, on the one hand, and between these three fractions and oxalate‐ and citrate‐dithionite‐bicarbonate‐extractable Fe, on the other, indicate a common origin for the inorganic P in the three fractions as part of a short range order Fe‐rich complex. Apatite was low in all sediments.
Decomposition of Urea Phosphate in Soils
Authors: Bremner J. M. , Douglas L. A. 
Published: July 2010

AbstractStudies of the decomposition of urea phosphate (NH2CO‐NH2 · H3PO4) in soils showed that the phosphoric acid in this compound retards enzymatic hydrolysis of the urea by soil urease and reduces gaseous loss of urea N as ammonia. When soils treated with urea and urea phosphate were incubated at 20C for 14 days, the percentage loss of urea N as ammonia was 4.6–61.1% (average, 21.2%) for the soils treated with urea, but was only 0.1–1.1% (average, 0.7%) for the soils treated with urea phosphate. The studies reported support the conclusion from previous work that urea phosphate has significant potential advantages over urea as a fertilizer.
Changes in DTPA‐Extractable Zinc, Iron, Manganese, and Copper in Soils Following Fertilization
Authors: Follett R. H. , Lindsay W. L. 
Published: July 2010

AbstractEleven soils were fertilized with Zn, Fe, Mn, and Cu and examined periodically with the DTPA micronutrient soil test. The study continued for 14 weeks while the soils were cropped in the greenhouse first with oats (Avena sativa) and then with corn (Zea mays). During this period fertilizer Cu declined to 61%, Zn to 44%, and Mn to 14% of their initial values. Only 20% of the Fe added as FeSO4 · 7H2O remained extractable after 1 week. With chelated Fe as FeEDDHA, 70% was extractable at 7 weeks and 26% at 14 weeks. The results are in general agreement with reported residual response from these fertilizers and suggest that the DTPA soil test may be useful for monitoring the availability of micronutrient cations in fertilized as well as unfertilized soils.
Soil Profile Gravel Layers: I. Effect on Water Storage, Distribution, and Evaporation
Authors: Unger Paul W. 
Published: July 2010

AbstractSoil water distribution and evaporation following water application were affected by a gravel layer placed on or 5, 15, or 25 cm below the soil surface. Soil above gravel retained more water than soil at similar depths in uniform columns. Evaporation from soil with gravel on the surface or at 5 cm was slower than from the check, while evaporation from soil with gravel at 15 or 25 cm generally was more rapid than from the check.The water content of soil near the surface of field plots was markedly influenced by rainfall or duration of rain‐free periods. For the entire soil mass sampled, gravel on or at 5 cm below the surface increased the water content of plots as compared with both the check plots and treatments with gravel at 15 or 25 cm during periods of relatively frequent precipitation (spring and early summer). All treatments, however, permitted considerable water losses during extended dry periods (late summer, fall, and winter).