bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial Dependence of Geochemical Elements in a Semiarid Agricultural Field: II. Geostatistical Properties
Authors: Berndtsson Ronny , Bahri Akissa , Jinno Kenji 
Published: July 2010

AbstractExperimental variograms may be used to infer the spatial structure of geochemical elements. This information is needed to control the transport of toxic elements through the unsaturated zone. Geostatistical properties of total soil contents for 20 major and trace elements were investigated for a soil in northern Tunisia. The analysis showed that all elements have a clear spatial structure. Several elements displayed a significant trend that was removed by fitting the raw data to a second‐order polynomial. Variograms for the residuals showed that most elements reach sills at ranges of ≈10 to 20 m. Exceptions are Co with a range of ≈1 m and Zn with a range of ≈5 m. The elements Be and Sr have larger ranges of ≈30 m. Calculation of direction‐dependent variograms showed that most elements depended on direction. Autocorrelation analysis of the residuals indicated no spatial correlation. The ranges found in this study can be used in sampling strategies to obtain independent values of geochemical elements.
Methodology for Determining Hydraulic Conductivity with Tension Infiltrometers
Authors: Logsdon S. D. , Jaynes D. B. 
Published: July 2010

AbstractTension infiltrometers have become a valuable tool for understanding infiltration in macropores and the soil matrix, but methodology varies. Our objective was to compare tension infiltrometer techniques and calculation procedures for determining unsaturated hydraulic conductivity, K(h), as a function of soil water pressure head (h). Field tension infiltrometer measurements were run to determine K(h) from: (i) steady‐state infiltration into an excavated one‐dimensional column, (ii) calculated sorptivity and measured change in soil water content for steady‐state three‐dimensional infiltration into dry soil, (iii) steady‐state three‐dimensional infiltration with two infiltrometer base sizes, and (iv) steady‐state infiltration for three negative heads at the same location using two different calculation schemes. For one scheme, a nonlinear regression method was used to fit α [a constant relating ln(K) and h] and K(0) from measured infiltration across three negative heads. The fitted α and K(0) were then used to calculate K(h) at each negative pressure head. Calculated K(h) by the nonlinear regression method from three‐dimensional infiltration measurements were 105% of measured one‐dimensional rates (from excavated columns), closer than any other method of calculation. More importantly, this method did not result in calculated K(h) less than zero or larger than three‐dimensional infiltration rates, as some calculation procedures did. The method did not depend on determinations of sorptivity or on initial or final soil water content.
Simultaneous Field Measurement of Nitrate‐Nitrogen and Matric Pressure Head
Authors: Moutonnet P. , Pagenel J. F. , Fardeau J. C. 
Published: July 2010

AbstractGroundwater protection from NO3 pollution requires frequent measurements of potential water fluxes and NO3‐N concentrations. This study was conducted to improve researchers' abilities in managing these two parameters by using a new device. We developed a method allowing the researcher to simultaneously measure the hydraulic head and the NO3‐N concentration in the soil water solution. Measurements were made using the tensionic, in which a permeable porous ceramic cup allows the diffusion of NO3 from the soil to the water inside the cup. Diffusion is completed within 8 d. A system of capillary tubes allows this water to be extracted for measurement of NO3‐N, and it may be reinjected subsequently. An aliquot can be used for isotopic analysis. Tests carried out on a maize crop (Zea mays L.) in 1991 led to two conclusions: (i) on a 200‐m‐long transect of 50 tensionics (placed at 4‐m intervals and at a depth of 50 cm), statistical analysis made on the first three of the successive series showed the consistency of measurements with an 18% mean coefficient of variation (CV) for NO−3, whereas the mean CV for hydraulic head was 14%; (ii) in a battery formation (four probes located at depths ranging from 40 to 130 cm, with four sampling repetitions), the tensionics allowed easy monitoring of the distributions of hydraulic head and NO3‐N within the horizons of the soil profile.
Cadmium Sorption on Specimen and Soil Smectites in Sodium and Calcium Electrolytes
Authors: Zachara J. M. , Smith S. C. , McKinley J. P. , Resch C. T. 
Published: July 2010

AbstractAlthough specimen smectities (e.g., SWy‐1) are often used as analogues of the exchanger phase in smectitic soils, few comparisons of metal ion sorption on specimen and soil smectites have been made. In this study, the sorption of Cd was measured on SWy‐1 and on clay‐sized separates from two smectitic subsoils to evaluate the selectivity of specimen and soil‐derived smectites for Cd. Sorption was measured in clay suspensions (≈1 mmolc L−1 equivalent charge concentration at pH 6.0) in Na+, Ca2+, and Na+‐Ca2+ perchlorate solutions across pH 4.5 to 8.5 and at ionic strengths (I) ranging from 0.005 to 0.1. Ionic strength and electrolyte cation valence strongly influenced Cd sorption by SWy‐1 and the soil smectites. Ion exchange dominated Cd sorption at low ionic strength in Na+ electrolyte (I = 0.005–0.014). Increasing Na+ concentrations to I = 0.1 or changing the electrolyte cation to Ca2+ at I = 0.003 to 0.006 suppressed ion exchange. When ion exchange was suppressed, Cd sorption to both specimen and soil smectites showed little dependence on ionic strength and increased with pH. Except at the lowest Na+ concentration (I = 0.005), conditional equilibrium constants (Kv) for Cd2+ exchange increased with increases in both ionic strength and pH. These increases were ascribed to Cd complexation reactions to edge sites on the layer silicates whose effects became evident only under conditions that suppressed ion exchange. At pH 6 and I = 0.05–0.01, SWy‐1 did not exhibit any preference for Na+, Ca2+, or Cd2+. The smectitic soil separates, in contrast, showed (i) sorption behavior that increased sharply with pH, (ii) preference for Cd in Na+ and Ca2+ electrolytes, and (iii) variation in Kv with ionic strength, pH, and surface coverage. The contrasting sorption behavior of the soil smectites was hypothesized to result from (i) a greater edge surface area, which increased the contribution of oxidelike complexation reactions to Cd sorption, and (ii) the presence of minor associated organic material and Fe oxides that functioned as co‐complexants for Cd.
New Evidence for the Origin of Ferrimagnetic Minerals in Loess from China
Authors: Fine Pinchas , Singer Michael J. , Verosub Kenneth L. , TenPas Jeff 
Published: July 2010

AbstractThe sequence of loess and interbedded paleosols of north‐central China has accumulated for the last 2.4 million yr. This offers a unique location to study pedogenesis. The paleosol units are easily differentiated from zones of unaltered parent material by their higher low‐field mass magnetic susceptibility (MS). We have studied the MS of 69 loess and paleosol samples to determine if MS could be used to understand more about pedogenesis in the loess column. The MS ranged from 11 × 10−8 m3 kg−1 in an unaltered loess to 324 × 10−8 m3 kg−1 in a paleosol. We present magnetic and chemical data that support the in situ formation of ferrimagnetic material during periods of pedogenesis. An inherited ferrimagnetic component, which is predominantly silt‐sized magnetite, is evenly distributed throughout the loess column with an average MS of 17 ± 4 × 10−8 m3 kg−1. This component is resistant to removal by citrate‐bicarbonate‐dithionite (CBD) extraction. A second ferrimagnetic component, with is CBD soluble, occurs predominantly in the clay (<2‐µm) fraction. We assume this material is a newly formed maghemite that has accumulated in the paleosols as a result of pedogenesis. This CBD‐soluble ferrimagnetic phase is enriched in the paleosols, as shown by the linear (P < 0.001) increase of the ratio of MS to Fe oxides and oxyhydroxides. The ferrimagnetic content, ferrimagnetic minerals, and particle‐size distribution of the ferrimagnetic phase in the paleosols are all related to the extent of pedogenesis in the loess column.
Effect of Landscape Position on Soil Water and Corn Silage Yield
Authors: Afyuni M. M. , Cassel D. K. , Robarge W. P. 
Published: July 2010

AbstractSystematic variation in plant‐available water at different landscape positions is thought to be one of the most important factors controlling crop production. The objectives of this study were to evaluate variability in equivalent depth of soil water, plant‐available water, and soil water pressure as a function of landscape position and their effects on corn (Zea mays L.) silage production. Soil water content to a depth of 1 m and soil water pressure at depths of 30, 45, and 60 cm were monitored at 5‐m intervals on an 110‐m‐long transect, and at 10‐m intervals on an 80‐m‐long transect using neutron attenuation and tensiometers, respectively. Plant‐available water at a given time was calculated as field‐measured soil water content minus the soil water content at −1500 kPa. Corn silage yield was measured on 13.5‐m2 plots centered at 5‐ or 10‐m intervals and grouped by landscape position. The foot slope position had the lowest total water content on both transects, but the greatest amount of plant‐available water on the longer transect. Equivalent depth of soil water in the upper 1 m of soil decreased from the interfluve to the footslope position and was negatively correlated with silage yield. Soil water pressures were greater at the footslope than the other landscape positions and were positively correlated with silage yield in the shorter transect.
Hydraulic Conductivity of Saline‐Sodic Soil after Gypsum Application and Cropping
Authors: Ilyas M. , Miller R. W. , Qureshi R. H. 
Published: July 2010

AbstractSlow internal drainage is a major problem in the reclamation of saline‐sodic soils. This field experiment was conducted on a low‐permeability, saline‐sodic soil (a fine‐loamy, mixed, thermic Typic Natrustalf) near Lahore, Pakistan, to compare field‐saturated hydraulic conductivities (Kfs) after various treatments. Treatments were: (i) deep‐rooted perennial alfalfa (Medicago sativa L.), (ii) sesbania [Sesbania bispinosa (Jacq.) W.F. Wright]‐wheat (Triticum aestivum L.)‐sesbania rotation, (iii) incorporated wheat straw at 7.5 Mg Ha−1, and (iv) a fallow control. These four treatments were each combined with and without 25 Mg ha−1 of gypsum, subsoiling to 0.45 m, and open‐ditch drainage. The Kfs of the soil under each treatment was measured in each 20‐cm increment to 120 cm after 6 mo and 1 yr. Gypsum applications increased the Kfs of the top 20‐cm soil layers. Compared with uncropped plots, Kfs of the 0‐ to 20‐cm depth on cropped plots with gypsum increased about twofold after 6 mo and about fourfold after 1 yr. The crop rotation significantly increased the Kfs of the 0‐ to 20‐cm (with and without gypsum) when compared with wheat straw or fallow treatments. The Kfs on plots with alfalfa plus gypsum were significantly greater to 80 cm than the Kfs on fallow plots. Neither subsoiling nor open‐ditch drains improved soil permeability. Gypsum plus sesbania‐wheat‐sesbania rotation most increased permeability of the surface layer; gypsum plus alfalfa was best to improve the permeability of the deeper layers.
Variations in Water Balance and Recharge Potential at Three Western Desert Sites
Authors: Gee G. W. , Wierenga P. J. , Andraski B.J. , Young M. H. , Fayer M. J. , Rockhold M. L. 
Published: July 2010

AbstractRadioactive and hazardous waste landfills exist at numerous desert locations in the USA. At these locations, annual precipitation is low and soils are generally dry, yet little is known about recharge of water and transport of contaminants to the water table. Recent water balance measurements made at three desert locations, Las Cruces, NM, Beatty, NV, and the U.S. Department of Energy's Hanford Site in the state of Washington, provide information on recharge potential under three distinctly different climate and soil conditions. All three sites show water storage increases with time when soils are coarse textured and plants are removed from the surface, the rate of increase being influenced by climatic variables such as precipitation, radiation, temperature, and wind. Lysimeter data from Hanford and Las Cruces indicate that deep drainage (recharge) from bare, sandy soils can range from 10 to >50% of the annual precipitation. At Hanford, when desert plants are present on sandy or gravelly surface soils, deep drainage is reduced but not eliminated. When surface soils are silt loams, deep drainage is eliminated whether plants are present or not. At Las Cruces and Beatty, the presence of plants eliminated deep drainage at the measurement sites. Differences in water balance between sites are attributed to precipitation quantity and distribution and to soil and vegetation types. The implication for waste management at desert locations is that surface soil properties and plant characteristics must be considered in waste site design in order to minimize recharge potential.
Plant Response to Organic Amendments and Decreasing Inorganic Nitrogen Rates in Soils froma Long‐Term Experiment
Authors: Fauci Mary F. , Dick R. P. 
Published: July 2010

AbstractTo decrease the potential for adverse environmental impacts of N in agroecosystems, there is increasing emphasis on improving N efficiency of organic and inorganic sources. Greater reliance on organic N sources can cause short‐term crop yield decreases. Consequently, a study was conducted to determine the effect of decreasing rates of inorganic N during a transition from inorganic to organic N sources. The approach was to grow four crops of maize (Zea mays L.) during a period of 306 d in the greenhouse on soils that varied widely in organic matter and biological activity because of long‐term residue and fertilizer management. Treatments were arranged as a complete factorial with the following factors: four soils obtained from the Residue Utilization Plots (RUP), Columbia Basin Research Center, Pendleton, OR (beef manure or pea [Pisum sativum L.] vine residue, 0 or 90 kg N ha−1, applied biennially since 1931); four greenhouse amendments (pea vine, composted beef or poultry manure, or control); and four rates of N fertilizer (0–1600 mg N [2 kg]−1 soil as NH4NO3). In the absence of organic residue or N fertilizer, soil from the manure RUP produced greater dry matter yield (DMY) and plant N uptake than soil from the other RUP treatments. There was no net N mineralization from beef manure added in the greenhouse. Between 10 and 30% of the total poultry manure and pea vine N added was taken up by the four maize crops. Results showed that, by the fourth crop, when inorganic N applications had decreased to zero, plant productivity by organic residues was best maintained by pea vine residue or poultry manure.
Ammonia Volatilization from Urea Amended with Lignosulfonate and Phosphoroamide
Authors: Al‐Kanani T. , MacKenzie A. F. , Fyles J. W. , O'Halloran I. P. , Ghazala S. 
Published: July 2010

AbstractConcern about losses of fertilizer N and pollution of the environment has stimulated research to find compounds that will reduce these problems by effectively inhibiting urease activity and nitrification. Laboratory studies were carried out to evaluate the effects of ammonium lignosulfonate (LS), thiophosphoric triamide (NBPT), and phenylphosphorodiamide (PPD) on NH3 loss from urea fertilizer. We examined NH3 losses from surface‐applied urea and from banded urea (2 cm below the soil surface) in samples of Ste. Rosalie clay soil (fine, mixed, nonacid, mesic Typic Humaquept) exposed to an initial water pressure of −0.01 MPa. Formulations of solution, physical dry blend, and tablets were used. Measurements of NH3 volatilization were carried out using an air train system. Ammonia loss from surface‐applied unamended urea ranged from 16 to 21% of urea‐N applied. Amending urea with LS induced between 46 and 85% reduction in NH3 losses compared with the unamended urea. For tablet and physical dry blend formulations, banding reduced NH3 loss compared with tbe surface application. There were no significant differences in NH3 losses between surface‐applied and banded treatments of solid fertilizer. Comparison of tbe effects of LS, NBPT, and PPD on NH3 volatilization showed that both NBPT and PPD were more effective in reducing NH3 loss than LS, but no significant differences between NBPT and PPD were found.
Corn Yield and Phosphorous Uptake with Banded Urea and Phosphate Mixtures
Authors: Fan M. X. , MacKenzie A. F. 
Published: July 2010

AbstractLow fertilizer P use efficiency is a problem in crop production on acid soils, but efficiency can be affected by methods of fertilizer application. A field experiment was conducted on two eastern Canadian soils (fine‐silty to fine, mixed, frigid Typic Humaquepts) with different pH (5.0 and 6.0 initially) to evaluate the effect of banding different rates of urea with acidic P fertilizers on corn (Zea mays L.) yield and fertilizer use efficiency. Three rates of urea (0, 30, and 60 kg N ha−1) banded with two sources of P (triple superphosphate [TSP] and monoammonium phosphate [MAP] at 38.7 kg P ha−1) or alone without P fertilizer, as control, were studied in 1990. In 1991, three rates of TSP (0, 19.4, and 38.7 kg P ha−1) were used in combination with the same three rates of urea to determine the effect of banding ratio of urea‐N/TSP‐P. The residual fertilizer effects of the 1990 treatment were investigated in 1991. Banding urea with TSP or MAP increased soil extractable P (Mehlich III). At the six‐leaf stage, plant P concentrations and dry matter yield increased linearly with both banded N and P in the Ste. Rosalie soil, and quadratically in the Ormstown soil. Total N and P uptake by corn increased in both years by banding urea with TSP or MAP, and fertilizer P use efficiency increased by 40 to 80%. Urea banded with P increased grain yield in both soils. No interactions were found between banded N rates and P sources in 1990, and between banded N rates and P rates in 1991. Greater residual effects of P fertilizer were found on grain yields and P uptake where P was banded with urea compared with no urea.
Soil Water Content and Potential Measured by Hollow Time Domain Reflectometry Probe
Authors: Baumgartner Norbert , Parkin Gary W. , Elrick David E. 
Published: July 2010

AbstractA new soil probe used in conjunction with time domain reflectometry (TDR), tensiometry, and solution extraction devices and designed to allow simultaneous in situ measurement of soil‐water content, matric potential, and solute concentration is proposed. Hollow stainless steel electrodes with a porous stainless steel tip serve as TDR wave guides in a standard two‐parallel‐probe configuration. The porous tip allows water inside the hollow rods to equilibrate with the soil water in an unsaturated or saturated system. A pressure transducer system is used to measure the soil matric potential around the porous tip. A vacuum pump can be used to withdraw soil solution through the permeable porous tip. A preliminary comparison between measurements of soilwater content obtained by a two‐solid‐wires TDR probe and the new probe gave encouraging results. Favorable agreement was obtained between measurements of the soil matric potential and depth to an artificial water table.
Nitrogen Mineralization and Ammonia Volatilization from Fractionated Poultry Litter
Authors: Cabrera M. L. , Tyson S. C. , Kelley T. R. , Pancorbo O. C. , Merka W. C. , Thompson S. A. 
Published: July 2010

AbstractPassing poultry litter through a 0.83‐mm sieve generates a fine fraction higher in N concentration and cheaper to transport per unit of N than the whole litter. One objective of this work was to determine if the organic N in the fine fraction undergoes faster mineralization than that in the whole litter. Whole litter or fine fraction from three poultry houses was either mixed with samples of Dothan loamy sand (fine‐loamy, siliceous, thermic Plinthic Kandiudult) or applied on the soil surface at a rate of 100 kg N ha−1. The treatments were incubated at water field capacity and 27°C, with samples extracted at 3, 7, and 14 d. Differences in N mineralization were relatively small between materials; by Day 14, the organic N had undergone a slightly higher mineralization in the fine fraction (51.5%) than in the whole litter (44.5%). A second objective was to compare the potentials for net N mineralization, NH3 volatilization, and respiration of whole poultry litter and fine fraction stored for 7 d at 25 °C and at two water contents (unamended [0.12–0.26 kg H2O kg−1] and 0.5 kg H2O kg−1). On an equal‐mass basis, net N mineralization and NH3 volatilization were larger in the fine fraction than in the whole litter, whereas respiration was similar in both materials. All processes increased with an increase in water content. These results suggest that the fine fraction should be managed similarly to the whole litter when applied to soil and that it may lose more NH3 than does the whole litter during storage, particularly at relatively high water contents.
Decomposition and Nitrogen Dynamics of Crop Residues: Residue Quality and Water Effects
Authors: Schomberg H. H. , Steiner J. L. , Unger P. W. 
Published: July 2010

AbstractUnderstanding environmental and residue influences on decomposition and nutrient dynamics under diverse conditions is critical for efficient resource management. Our objective was to evaluate the influence of water on decomposition and N dynamics for surface and buried residues. Decomposition of alfalfa (Medicago sativa L.), grain sorghum (Sorghum bicolor [L.] Moench), and winter wheat (Triticum aestivum L. emend. Thell.) residues in fiberglass bags on the surface or buried at 120 mm in Pullman soil (fine, mixed, thermic Torrertic Paleustoll) at Bushland, TX, was measured from May 1990 to May 1991. A line‐source sprinkler provided five water regimes (336, 287, 166, 60, and 5 mm) while precipitation provided 305 mm water. Decomposition coefficients (k) were greater for alfalfa than for wheat or grain sorghum and were greater for buried than for surface residues. Rate coefficients increased linearly with water applied. The increase was greater for alfalfa than for sorghum and wheat. Net N mineralization occurred from alfalfa residues throughout the study. Net N immobilization was longer than 1 yr for surface wheat and sorghum and about 0.33 yr for buried residues. Both Nmax (grams N immobilized per kilogram of original biomass) and Neqv (grams N immobilized per kilogram of biomass loss) were influenced by crop and placement but not water regime. The Nmax value was similar for surface wheat and sorghum residues but was 50% lower for buried wheat than for sorghum. The Neqv indicated the N requirement of microorganisms was less for buried than for surface residues. Water and residue quality interactions affecting decomposition and N dynamics should be considered in residue management strategies for soil protection and nutrient cycling.