bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimating Ammonia Volatilization From Flooded Rice Fields by Simplified Techniques
Authors: Freney J. R. , Leuning R. , Simpson J. R. , Denmead O. T. , Muirhead W. A. 
Published: July 2010

AbstractTwo simplified methods for assessing the emission of ammonia, from fertilized, flooded rice (Oryza sativa L. cv. Inga) fields without affecting the plant's environment, are described and compared with an established micrometeorological method. Method A requires a circular plot of a 25‐m radius over which wind speed and atmospheric ammonia concentrations are observed at 0.8 m above the floodwater. Method B requires measurements of ammoniacal nitrogen concentration, pH and temperature in the floodwater, and wind speed at a fixed height. Method A is the more accurate technique and requires fewer measurements. It appears that one calibration curve relating vertical flux of ammonia to these measurements can be applied in widely different environments. Method B is not only less accurate than Method A but appears to require different calibration curves to determine vertical flux for different environments. However, this method may be more useful for comparing ammonia losses from several different fertilizer treatments since only small plot areas are required for each treatment. Method B can be calibrated easily for each site by one set of simultaneous measurements on one treatment plot, using Method A.
Spatial Variability of a Cultivated Soil as Affected by Past and Present Microtopography
Authors: Kachanoski R. G. , Rolston D. E. , de Jong E. 
Published: July 2010

AbstractThe effects of 30 yr of cultivation on the magnitude and spatial variance relationships of selected soil properties are examined. Soil cores (76‐mm diam) were taken every 1 m in 46‐m long transects in a native and adjacent cultivated field. The soil is a mixture of Typic Haploborolls and Typic Argiborolls. Spatial relationships observed in the native soil were used to construct a moving average model for predicting the soil surface on the cultivated site that existed before cultivation. The model along with 137Cs distribution was used to separate the effects of tillage translocation and erosion on changes in solum mass and C. Tillage translocation during the initial years of cultivation resulted in considerable redistribution of soil. Spectral analysis indicated the redistribution was not random, but was related to the spatial distribution of the past surface curvature. The systematic redistribution resulted in higher overall variances for soil properties compared to the native site, but also resulted in significant increases in autocorrelation and the proportion of variance associated with deterministic cycling. A conceptual and mathematical filter model is presented for representing the effects of management, weathering, or other treatments on the soil. In profiles where no significant tillage translocation occurred, total C losses in the solum were 0.35% (of original C) per year. Soil erosion could account for 40% of the observed total C loss.
Model for the Soil Solution Composition of an Oasis
Authors: Elprince Adel M. 
Published: July 2010

AbstractA static computer model based on the evaporative concentration of irrigation waters has been developed for the origin of soil solution compositions in the Al‐Hassa oasis in Saudi Arabia. The model successfully predicted the precipitation of calcite and the conversion of smectite to attapulgite when in equilibrium with atmospheric CO2 pressure. It also predicted precipitation of gypsum when irrigation water is concentrated by a factor of 3.7 and the precipitation of silica gel when water is concentrated by a factor of 7.5. Results from this study indicate that the model may be applicable to other oases in arid environments. Spring water discharges freely from the higher elevations and flows toward playas in the desert. Mineral fractionation follows the same natural slope within the oasis, as indicated by isoconcentration lines for salinity, carbonates, and gypsum in oasis soils. The calculated soil solution compositions at fixed electrolytic conductivity (EC) values were compared with the chemical analysis of 1:5 extracts having the same EC values. These comparisons showed that six primary processes are responsible for the formation of soil solutions from irrigation water under oases conditions. The processes are: (i) deaquation due to transpiration and evaporation, (ii) precipitation and dissolution of soil mineral phases, (iii) K fixation, (iv) Na and Cl retention, (v) MgSO04 formation, and (vi) biological formation of HCO3. Agricultural production of dates was absent in areas where the EC of 1:5 soil solution extracts exceeded 6 dS m−1 (i.e., in gypsum and silica gel precipitation areas).
Sodium‐Calcium‐Magnesium Exchange Reactions on a Montmorillonitic Soil: III. Calcium‐Magnesium Exchange Selectivity
Authors: Sposito Garrison , Fletcher Philip 
Published: July 2010

AbstractThe Vanselow selectivity coefficient was calculated for Mg → Ca exchange on a montmorillonitic soil separate containing organic matter. Seven sets of cation exchange data were analyzed numerically, encompassing pH values ranging from 5 to 7 in a 50 mol m−3 perchlorate medium and exchangeable sodium percentages ranging from 0 to 25%. The selectivity coefficient for Mg → Ca exchange was observed to decrease from a value near 1.5 at 0% Ca saturation to a value near 1.0 at 100% Ca saturation with no effect of pH on this trend in the range examined. At low Ca saturation of the soil, the selectivity coefficient increased by about 15% as the ESP increased from 0 to 25%. This behavior was shown through a model calculation to be consistent with a mechanism in which Na adsorbs preferentially on the montmorillonitic component of the exchange complex in the soil, leaving the nonmontmorillonitic portion of the exchange complex to adsorb Ca selectively over Mg.
Loess Deposits on a Pleistocene Age Terrace in Eastern Arkansas
Authors: Rutledge E. M. , West L. T. , Omakupt Manu 
Published: July 2010

AbstractThe area of eastern Arkansas between Crowley's Ridge and the Ozark Plateau, known as the Western Lowlands of Arkansas, was shaped by the ancestor of the Mississippi River. As this river responded to changes in glaciers upstream, a series of five braided stream terraces was formed within the lowlands. The second highest of these terraces was transected normal to its long axis to determine whether the silty materials capping this terrace were loess or silty alluvium and to determine the source area for any loess deposit(s). Two silty deposits were identified on the terrace by morphology, fine‐earth and clay‐free particle size distribution, and total Ca and K distribution. Relationships between clay‐free silt fractions and distance from a loess source, which are similar to relationships developed for other loess deposits, were utilized to locate source areas and to demonstrate the loessial nature of both deposits. The surface deposit, Peoria Loess, was correlated as a continuation of the Peoria Loess on Crowley's Ridge which had its source area in the lowlands east of Crowley's Ridge. The lower deposit, correlated as Loveland Silt, had a well‐developed paleosol in its upper part. The main source area for this loess was the lowlands west of the study terrace.
Conservation Tillage Systems for Cotton Production
Authors: Brown S. M. , Whitwell T. , Touchton J. T. , Burmester C. H. 
Published: July 2010

AbstractCotton (Gossypium hirsutum L.) production is intensive in many areas of the southeastern USA, and the common tillage system used is a highly erosive fall plow‐winter fallow‐spring disk. The primary purpose of this 3‐yr field study was to evaluate seeding systems for winter cover crops, effect of cover crop management on cotton production, and N fertilizer requirements for cotton following various winter cover crops. Treatments consisted of (i) winter cropping systems [fall plow‐winter fallow; winter fallow; and three cover crops, rye (Secale cereale L.), hairy vetch (Vicia villosa Roth.), and crimson clover (Trifolium incarnatum L.)]; (ii) cover crop seeding methods (broadcast interseeded prior to cotton defoliation or drill seeded after picking); (iii) spring tillage (disk or no tillage prior to cotton planting); and (iv) N rates for cotton (0, 34, 67, and 101 kg N ha−1). The soil was a Decatur silt loam (clayey, kaolinitic, thermic, Typic Paleudults). Interseeding resulted in adequate cover crop stands for all covers each year, but drill seeded clover winter killed 2 out of 3 yr. Total N in the legume tissue at cotton planting was higher for interseeded (120–145 kg N ha−1) than drill seeded (33–86 kg N ha−1). In 1 of the 3 yr, cotton seedling mortality was higher with no tillage than disk tillage. None of the conservation‐tillage systems resulted in higher cotton yields than the fall plow system. Planting into killed rye resulted in yields equal to the fall plow system, but more fertilizer N (approximately 34 kg N ha−1) was required for cotton planted into rye. When cotton followed vetch, yields were equal to the fall plow system in 2 of the 3 yr, and N fertilizer requirements were reduced approximately 34 kg ha−1. When compared with fall plow, no tillage into clover or winter fallowed soils resulted in inferior cotton yields each year.
Effect of Electrolytic Concentration on the Hydraulic Properties of Depositional Crust
Authors: Shainberg I. , Singer M. J. 
Published: July 2010

AbstractDepositional crusts form when turbid water infiltrates into soil. These crusts reduce the rate of water penetration. Hydraulic conductivity of two California soils was measured as a function of volume of suspension infiltrated and electrolytic concentration in the range ≤ 0.005 M. Whereas the hydraulic conductivity of the bulk soils was not affected by electrolytic concentration; the hydraulic conductivity of the soil columns with depositional crust increased by two orders of magnitude as the electrical conductivity (EC) of the suspension increased from 0.1 to 0.55 dS m−1. Saturated hydraulic conductivity of depositional crust made of flocculated particles was much higher than saturated hydraulic conductivity (HC) of crust made of dispersed clay and silt particles. Drying of the crusted soils destroyed the crust and restored the rate of water penetration. The curves of water penetration in consecutive irrigations were similar to that in the first irrigation. Phosphogypsum maintained high water penetration in three consecutive irrigations by increasing the electrolytic concentration in the solution above the clay flocculation values.
Factors Affecting the Mineralization of Nitrogen in Sewage Sludge Applied to Soils
Authors: Barbarika Alexander , Sikora Lawrence J. , Colacicco Daniel 
Published: July 2010

AbstractAn investigation to determine the factors affecting the rate of N mineralization in sewage sludge amended soils using multiple regression techniques was undertaken. Five published incubation studies involving 11 different sludges were analyzed. Both soil and sludge factors were considered in the statistical analyses. Factors positively affecting mineralization rate were total N content of the soil, and the duration and temperature of the incubation. Negatively affecting mineralization were the C/N ratios of the sludge and soil. Two of the estimated equations resulting from the statistical analyses were tested on the results of a sixth incubation study in which several different sludges were incubated under the same time, temperature, moisture, and amendment rate conditions and a 0.75 correlation coefficient was obtained. The resulting model equation using data from all six studies indicated that soil factors are important variables in predicting mineralization of N in sewage sludge amended soils.
Effects of Phenylphosphorodiamidate and Dicyandiamide on Nitrogen Loss from Flooded Rice
Authors: Simpson J. R. , Freney J. R. , Muirhead W. A. , Leuning R. 
Published: July 2010

AbstractThe effects of a urease inhibitor, phenylphosphorodiamidate (PPD), and a nitrification inhibitor, dicyandiamide (DCD), on the losses, tranformations, and recovery of nitrogen (N) were studied when urea was applied to a flooded rice field near Griffith, New South Wales (NSW). When PPD was applied with urea to the floodwater, urea hydrolysis was not prevented but merely delayed by ∼4 d. Consequently, the accumulation of ammoniacal N in the floodwater was also delayed. The maximum ammoniacal N concentration was reached after 3 d in the urea control, and after 9 d in the urea + PPD treatment. The relative losses of ammonia (NH3) from the treatments thus depended on the temperatures and pH of the floodwater and the windspeeds prevailing during the respective periods when the concentration of ammoniacal N was high. Low windspeeds at 8 to 10‐d after application caused NH3 loss on the PPD‐treated plots to be less than on urea‐only plots, but this was fortuitous and an opposite effect might have occurred. The 15N balance on microplots which received labelled urea showed that PPD addition increased recovery of urea N in the plant‐soil system from 60 to 82%. Plant uptake of labelled N was increased by 56%. After subtracting NH3 volatilization and any other potential losses, the resultant N balance suggested that PPD addition had allowed more urea N to be retained in the soil surface layer (0–10 mm) in such a way that nitrification‐denitrification loss was substantially reduced. The nitrification inhibitor (DCD) had no significant effect on nitrate concentrations in the floodwater, NH3 loss, or recovery of fertilizer N in plants and soil.
Nutritional Complexities Associated with pH Variables in Humid Tropical Soils
Authors: Fox R. L. , Yost R. S. , Saidy N. A. , Kang B. T. 
Published: July 2010

AbstractSoil fertility problems associated with soil acidity in the humid tropics were identified by observing variations of some growth‐controlling factors along response curves. Data for these curves were generated by liming an Oxisol and an Ultisol of Hawaii so that pH increased progressively, from <5 to > 7. Legumes were grown across the pH gradients. Liming the Oxisol depressed Al concentration in the pH range 4.8 to 5.5 and Mn in the pH range 4.8 to 5.7. Liming did not change solution Ca until pH 5.7 was reached, after which, solution Ca contents of saturation extracts increased exponentially. The beneficial effects of liming Leucaena leucocephala were linear from pH 4.8 to 7.0. Soybean (Glycine max L.) yields increased abruptly at approximately pH 5.9 which corresponded to increased Ca concentration in soil saturation extracts. Indigenous soil microvariability in the humid tropics, although sometimes disastrous to conventional field plot experimentation, provides opportunities for investigating soil‐plant relations in ways that are difficult to duplicate by design. Such variability made possible an indigenous‐function investigation using soybeans growing on an Alfisol of Nigeria. Increasing yield with increasing soil pH of the Alfisol was associated with increased N fixation, and this with decreased Mn in the foliage. Predicted N yield was zero at approximately 600 mg Mn kg−1 leaf tissue. Vigorous soybean plants contained 1.5% leaf K, which was associated with at least 0.25 cmol K kg−1 soil. Exchangeable K was positively correlated with cation exchange capacity, and cation exchange capacity with soil pH. Results of this study demonstrate the complex relationships that exist between soil pH and crop nutrition in the humid tropics. It is unlikely that such complex relationships can be covered by simple unqualified statements about liming such soils.
Characteristics of Wisconsinan Glacial Tills in Indiana and Their Influence on Argillic Horizon Development
Authors: Franzmeier D. P. , Bryant R. B. , Steinhardt G. C. 
Published: July 2010

AbstractIn relatively young soil landscapes the parent material largely controls the properties of soils formed on it. Glaciers of the Tazewell subage (15 000–21 000 yr ago) covered the northern two‐thirds of Indiana and glaciers of the Cary subage (15 000–12 000 yr ago) covered the northern third. Particle size distribution, calcium carbonate equivalent (CCE), and calcite‐dolomite ratio were determined by standard soil characterization procedures on pedons sampled mainly during the course of the soil survey to represent till‐derived soils. These data were grouped into classes according to geographic areas defined by major end moraines and recognized ice‐margin positions and by new boundaries that separate areas shown to have different kinds of till in this study. Tazewell‐age till is mainly loam in texture and has a CCE between 200 and 300 g kg−1 (20 and 30%), but some in the eastern part of the state has CCE around 350 to 400 g kg−1. The Cary‐age till in the north‐central part of the state also has loam (to sandy loam) texture and CCE around 200 to 250 g kg−1. In a series of concentric Cary‐age moraines in the northeast, average clay content increases from 27 to 37% and CCE decreases from 310 to 170 g kg−1 northeastward, reflecting increasing lacustrine influence in the younger tills. The clay content of the B horizon of till‐derived soils is a function of the clay content, CCE, and age of the glacial till parent material.
Phosphorus Losses in Runoff As Affected by Tillage
Authors: Andraski B. J. , Mueller D. H. , Daniel T. C. 
Published: July 2010

AbstractLittle data are available on P losses in runoff from land under conservation tillage (CT) where the surface‐applied fertilizer variable has been eliminated. Thus, simulated rainfall was used to evaluate the comparative effects of four tillage systems on the losses of total P, dissolved molybdate‐reactive P (DMRP) and algal‐available P (AAP) where fertilizer was subsurface banded at planting. Tillage treatments included conventional (CN) and three CT systems: chisel plow (CH), till‐plant (TP) and no‐till (NT). Above‐ground portions of corn (Zea mays L.) plants were removed prior to simulation. Trials were conducted over a 4‐yr period, with individual trials being performed in June and July, September, or October of various years. The NT, CH, and TP treatments reduced total P losses by an average of 81, 70, and 59%, respectively, relative to CN. Concentrations and losses of total P among tillage treatments followed those for sediment concentrations and losses. Concentrations of DMRP were, in most cases, lowest for CN, although differences among treatments were generally small and not significant. With the exception of the first simulated rainfall trial (September 1980), no significant correlation was observed between DMRP concentrations and residue cover. Losses of DMRP for the CT treatments were similar to, or significantly lower than those for CN. Differences in AAP concentrations varied among treatments and sampling periods, although concentrations were usually lowest for NT. The relative percentage of AAP concentrations to total P concentrations increased over the course of this study. This increase was 6, 8, 26% higher for CH, TP, and NT, respectively, relative to CN. Relative to CN, the NT, CH, and TP treatments reduced AAP losses by an average of 63, 58, and 27%, respectively. These results indicate that CT systems can effectively reduce AAP losses in runoff relative to CN, especially at times when high sediment concentrations and losses occur from conventionally tilled land.
Referencing Water Content Effects on Soil Electrical Conductivity—Salinity Calibrations
Authors: Bottraud Jean‐Christophe , Rhoades J. D. 
Published: July 2010

AbstractThe effects of hysteresis on soil electrical conductivity (σa), matric potential (ψm), and σa‐volumetric water content (Θ) relations were evaluated for two matrix materials using laboratory column techniques. These σa‐Θ relations were found to be little dependent on whether changes in soil moisture occurred by drying or wetting. In contrast, σa‐Ψm relations displayed a strong hysteresis effect. It is concluded that Θ is a simpler and more accurate parameter to use for adjusting for soil moisture status when determining soil salinity from measurements of σa.
Field Aging of Transparent Polyethylene Mulches: I. Photometric Properties
Authors: Avissar R. , Mahrer Y. , Margulies L. , Katan J. 
Published: July 2010

AbstractField observation of the temperature regime of irrigated plots mulched with new and old (previously used during one solarization season) transparent polyethylene sheets, has shown that higher temperatures prevail under the old sheets. In order to explain this unexpected phenomenon, we measured the photometric properties (absorbance, transmittance, and reflectance in the ultraviolet‐visible and infrared regions of the radiation spectrum) of polyethylene mulches at four aging states encountered during prolonged field utilization. The measurements, carried out both in the field (with pyranometers) and in the laboratory (with spectrophotometers), show that the photometric properties change significantly during the aging process. Fine water droplets that condense on new polyethylene sheets reflect significantly more global radiation and better transmit infrared radiation than the soil deposits and water film found on polyethylene sheets after utilization during one solarization season. The thus increased incoming radiative flux at soil surface can explain the observed higher temperature.
Predicting Loblolly Pine Current Growth and Growth Response to Fertilization
Authors: Hart S. C. , Binkley Dan , Campbell R. G. 
Published: July 2010

AbstractVarious indices of N and P availability were tested for correlation with current stem volume growth and growth response to N + P fertilization of loblolly pine (Pinus taeda L.) plantations in the Coastal Plain of North Carolina. Although no single index or combination of indices significantly correlated with stem volume growth in unfertilized plots, several soil variables correlated well with growth in the fertilized plots (r = 0.79 for extractable soil Al, and r = 0.73 for NH+4‐N extracted by a boiling salt solution). Of the soil variables, only extractable soil Al correlated significantly with growth response to N + P fertilization. Volume growth in the unfertilized plots was the best predictor of growth response to fertilization (r = −0.82). Combining one of the P availability indices (double‐acid extractable or ion exchange resin PO4‐P) with growth in the unfertilized plots significantly increased the model's correlation with growth response (R = 0.88 and 0.93, respectively).
Introduction of Acetylene Into Soil for Measurement of Denitrification
Authors: McConnaughey P. K. , Duxbury J. M. 
Published: July 2010

AbstractGaseous N loss via denitrification can be measured with static flux chambers when acetylene (C2H2) is used to block nitrous oxide (N2) reduction. This paper describes a method for the introduction of C2H2 at low concentrations into the soil by diffusion. The method utilizes an above‐ground manifold connected to diffusion tubes inserted in the soil and C2H2 flows through the manifold at a rate of 0.33 mL s−1. Acetylene levels in the soil atmosphere within the flux chamber site ranged from 0.16 to 2.07 mol m−3, and the apparatus did not alter CO2 fluxes as measured by a static chamber method.