bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sample Size Consideration in the Determination of Soil Nitrate
Authors: Starr J. L. , Meisinger J. J. , Parkin T. B. 
Published: July 2010

AbstractA prerequisite to increasing N‐use efficiency through the use of soil testing is the accurate determination of soil nitrate concentrations. This study was conducted to determine the influence of sample size on the magnitude and variability of NO3‐N concentrations in the surface horizon of a Beltsville silt loam soil (fine‐loamy, mixed, mesic Typic Fragiudult). Five different sized soil coring tubes, 1.7 to 5.4 cm in diam. (38–366 cm3) and one block sample of 8770 cm3 were used to collect soil samples. Thirty‐six of each sample size were collected twice before and twice after planting corn (Zea mays L.). Nearly all the NO3‐N values were lognormally distributed with the magnitude of skewness related more to concentration than to sample size, except for the largest sample size (8770 cm3), which was always minimally skewed. This study indicated that mean NO3‐N values could be accurately estimated using 36 of the smallest sized samples. The smallest sample size, however, was often unable to accurately estimate the spatial variability of soil NO3‐N. Further, a computer‐intensive random resampling procedure indicated that 20 to 50% more samples were required with the smallest sampler to achieve satisfactory estimates of the sample mean. This study did not provide a consistent basis for choosing between samplers with diameters of 2.15 to 5.4 cm (58–366 cm3).
Surface and Subsurface Soil Acidity: Soybean Root Response to Sulfate‐Bearing Spent Lime
Authors: Marsh Brian H. , Grove J. H. 
Published: July 2010

AbstractSurface and subsurface acidity are of agronomic concern in the southeastern USA. The limits to crop production imposed by subsoil acidity need to be further defined for this region. Gypsum is being applied to ameliorate subsoil acidity and to overcome the problem of very slow lime movement from surface lime applications. Reduced crude conversion spent lime (RCCSL) containing anhydrite (CaSO4) was evaluated for use as a liming material with specific consideration given to the movement of SO2‐4 into the acid subsoil. Agricultural lime and RCCSL were applied at 0, 3.36, 6.72, and 10.08 Mg ha−1 to an acid Trappist silt loam (clayey, mixed, mesic Typic Hapludult). Soybean [Glycine max (L.) Merr.] was grown in the second year following lime application. Soil cores to 0.90 m were taken at growth stage R5 for root length measurement and soil chemical analyses. Yields were increased by the soil amendments and were well correlated with total root length (R2 = 0.84). Root growth below the surface limed layer was positively related to increased soil solution base cation (especially Ca) concentrations and SO2‐4 movement into the subsoil. Previously described solution Ca plus Al species activity models were not well related to field rooting responses. There remains a need for soil test procedures that predict the need for, and the amount of, subsurface acidity amelioration.
Land Use and Management Effects on Nonpoint Loading from Miamian Soil
Authors: Thomas M. L. , Lal R. , Logan T. , Fausey N. R. 
Published: July 2010

AbstractLand use greatly affects soil and hydrological processes, which have major implications for environmental quality and agricultural sustainability. The objective of this study was to determine the effects of four land use systems — continuous alfalfa, forest, ridge‐till corn (Zea mays L.) and conventional‐till corn — on runoff, soil loss, and nutrient transport in runoff and sediment. Eight field plots (18.5 by 21 m), equipped with 0.3‐m H‐flumes and FW‐1 water‐level recorders, were established on Miamian silty clay loam soil (fine, mixed, mesic Typic Hapludalf) at the Ohio State University Agronomy Farm, Columbus, OH. Runoff samples, collected after erosive storms during the growing season in 1990, were analyzed for sediment concentration, NO3‐N, NH4‐N, PO4‐P, and dissolved organic C. Sediment collected from the flume base was analyzed for total Kjeldahl N and available P. A critical period was identified as the early stages of crop growth during which the soil was particularly vulnerable to erosion due to excessive runoff. Soil and nutrient losses were typically higher during the critical than during the noncritical period. Both N and P losses in runoff and sediment were higher for cropped treatments than for alfalfa (Medicago sativa L.) and forest. Losses observed for conventional tillage were, however, several orders of magnitude larger than uncropped treatments.
Soil‐Based Irrigation and Salinity Management Model: II. Water and Solute Movement Calculations
Authors: Cardon G. E. , Letey J. 
Published: July 2010

AbstractThe utility of a new model for irrigation and soil salinity management is based largely on the agreement between measured and predicted water and solute movement in the soil profile. Data suitable for comparison to model calculations is lacking in the literature. We conducted a greenhouse study designed to obtain detailed temporal salt and water distribution data under fluctuating shallow saline water table conditions, and compared simulated and observed data. Our model's calculations for water content and salinity agreed well with the observed distributions. Willmott's d index (a statistical index of agreement between measured and observed data) results ranged from 0.83 to 0.97 (perfect agreement = 1.0). Agreement was improved when potential evapotranspiration (PET) estimates were adjusted for data from individual treatment columns in the greenhouse experiment. The d‐index values, following adjustment of PET, increased to 0.94 or bigher, indicating the importance of accurate localized PET estimates for optimum model performance.
Immobilization and Uptake of Nitrogen Applied to Corn as Starter Fertilizer
Authors: Francis D. D. , Doran J. W. , Lohry R. D. 
Published: July 2010

AbstractOne goal of best management practices for N fertilization is to obtain high utilization of applied fertilizer. This experiment was conducted to determine plant uptake and the degree of microbial immobilization of NH4‐N and NO3‐N in fluid starter fertilizer applied to corn (Zea mays L.). In addition, two modifications of the fumigation‐incubation method for biomass C and N determinations were evaluated for their ability to quantify immobilization of fertilizer N by soil microbial populations. Starter fertilizers tagged with 14NH4NO3 or NH415NO3 were used to measure effects related to the fertilizer NH4 and NO3 components. Plant and soil samples were collected at the V3 and V8 growth stages. In both years, NO3 in the starter fertilizer was leached out of the emerging plant's root zone before it could be fully utilized. Ammonium underwent rapid nitrification and subsequently also was leached out of the topsoil, limiting immobilization and plant uptake. In the second year of the study, dicyandiamide (DCD) was included in the treatments, which maintained more N in the NH4 form, resulting in greater crop uptake and more microbial immobilization of fertilizer N. Under environments that tend to be conducive to leaching, it may be necessary to add a nitrification inhibitor to starter fertilizers to ensure that fertilizer N remains positionally available to young corn plants. The Shen, Pruden, and Jenkinson method for estimating biomass N gave immobilization values that were consistent with values anticipated from isotopic analyses of soil N. The Voroney and Paul technique appeared to overestimate biomass N by 1.5‐ to seven fold for our soils and climatic conditions.
Micromorphological Evidence of Polygenesis of Three Aridisols, Western Mojave Desert, California
Authors: Eghbal Mostafa K. , Southard Randal J. 
Published: July 2010

AbstractSoils in arid regions are often polygenetically related to climatic variation. On a dissected alluvial fan in the western Mojave Desert, a Typic Durorthid (loamy, mixed, thermic, shallow; Alko series) and two Typic Haplargids (fine‐loamy, mixed, thermic; Neuralia and Garlock series) were selected for micromorphological investigation to determine the sequence of pedogenic events. The micromorphology of pedogenic silica, carbonate, and clay is described for duripans, duric horizons (Btqk), and underlying buried Bt horizons in these soils. In the Alko and Neuralia soils, rodent bioturbation has transported subsurface calcareous fragments, thereby enriching the soil surface with silica and CaCO3. These fragments are not completely removed from the surface by leaching under the present‐day climate. Clay illuviation and silicification occurred simultaneously in the lower duripan (40–150 cm) of the Alko, with subsequent accumulation of CaCO3 in seams and root channels. Silicification of the Btqk and buried Bt horizons in the Neuralia and Garlock soils occurred after clay illuviation. The complete cementation of the lower duripan in the Alko soil has apparently isolated the buried Bt, but the buried Bt, horizons in the Neuralia and Garlock soils have undergone further calcification and silicification. We speculate that the polygenesis of soils in the study area is related to climatic fluctuations since the mid‐Pleistocene and to bioturbation of surface horizons. Development of carbonate‐free argillic horizons probably occurred during pluvial periods, whereas calcification occurred during drier periods. Silicification appears to have been contemporaneous with both clay illuviation and calcification and, thus, may be related to pedochemical conditions rather than to climate.
High Intensity X‐Ray and Tensiometer Measurements in Rapidly Changing Preferential Flow Fields
Authors: Liu Yaping , Bierck Barnes R. , Selker John S. , Steenhuis Tammo S. , Parlange J.‐Yves 
Published: July 2010

AbstractSynchrotron x‐rays at the Cornell High Energy Synchrotron Source (CHESS) and other available facilities provide a high‐resolution means of quantitatively studying rapid changes of fluid content in porous media. This technique is based on monitoring x‐ray absorbance changes in sand volumes traversed by an intense, highly collimated synchrotron x‐ray beam. The high intensity and brightness of synchrotron radiation permit acquisition of statistically significant x‐ray count data each second during the drying process of fingered flow. Simultaneous measurement of water pressure using tensiometers provides a reliable dynamic measurement of drying curves.
Predicting Saturated Hydraulic Conductivity Utilizing Fractal Principles
Authors: Rawls W. J. , Brakensiek D. L. , Logsdon S. D. 
Published: July 2010

AbstractPreferential movement of surface‐applied chemicals to the groundwater has resulted in a great need to physically model the movement of water into and through the soil media. The objective of this study was to develop equations capable of predicting both matrix and macropore saturated conductivity and to relate the equation parameters to readily available soil properties. Equations for predicting the matrix and macropore saturated conductivity were developed by coupling fractal processes with the Marshall saturated conductivity formulation. The equation uses matrix and macropore porosity, maximum pore radius, and number of pore classes. Prediction equations were developed relating the number of pore classes and maximum pore radius to soil properties. The modified Marshall saturated hydraulic conductivity equation appears to provide reasonable estimates of matrix and macropore saturated conductivity and is applicable to a wide range of soil textures.
Soil Microbial Populations and Activities in Reduced Chemical Input Agroecosystems
Authors: Kirchner M. J. , Wollum A. G. , King L. D. 
Published: July 2010

AbstractThis study, conducted in the Piedmont of North Carolina, was initiated to determine how reductions in N fertilization and green‐manuring with crimson clover (Trifolium incarnatum L. cv. Tibbee) would affect populations and activities of soil microorganisms. Four continuous corn (Zea mays L.) treatments were used: no‐till (receiving herbicides and soil insecticides) with 0 or 140 kg N ha−1 as NH4NO3; conventionally tilled, receiving 140 kg N ha−1, but no pesticides; and conventionally tilled with a crimson clover green manure, but no fertilizer or pesticides. Populations were determined using selective media for culturable bacteria, gram‐negative bacteria, fungi, actinomycetes, Bacillus spp., and Pseudomonas spp. Microbial activities were estimated by enzyme assays for acid and alkaline phosphatase, arylsulfatase, and β‐glucosidase. Microbial biomass C was determined by a chloroform fumigation‐extraction procedure and levels of available N were measured after anaerobic incubation. Surface soil (0–7.5 cm) from the no‐till treatment receiving 140 kg N ha−1 contained significantly more fungi than did soil from the unfertilized, no‐till treatment. Microbial biomass C and available N were not affected by N addition, but levels of acid phosphatase and β‐glucosidase were significantly higher in the fertilized soil than in the unfertilized soil. Surface soil from a crimson clover‐corn rotation contained significantly larger populations of Bacillus spp. (260% more), actinomycetes (310% more), and culturable bacteria (120% more) than did soil from the well‐fertilized conventionally tilled, no‐pesticide treatment. Also, microbial biomass, available N, and levels of alkaline phosphatase, arylsulfatase, and β‐glucosidase were significantly higher in surface soil from the crimson clover treatment than the nonmanured soil. Although the soil biological properties changed significantly during the year, seasonal variations were similar across treatments. Microbial numbers and activities were high in the spring and fall and low during the late summer.
Spatial Dependence of Geochemical Elements in a Semiarid Agricultural Field: I. Scale Properties
Authors: Bahri Akissa , Berndtsson Ronny , Jinno Kenji 
Published: July 2010

AbstractInformation on the spatial structure of soil chemical elements in field soils is needed to evaluate potential environmental hazards. Basic spatial properties of total soil contents of 20 major and trace elements were investigated for three different scales in a soil in northern Tunisia. In total, 314 soil samples were taken on two adjacent 40 by 40 m2 plots (one plot sludge‐amended and one without sludge). Theoretical lognormal probability distributions best fit the empirical distributions for most of the elements. Assuming complete randomness, a relative error margin of 10%, and a probability level of 0.05, average values for the sampled scales can be estimated with a minimum number of samples, which are 25 for Cd and Cr, 10 for Al, Be, Ca, Fe, Mg, and Pb, and five for other elements. The elements Al, Ca, and Fe can be sampled irrespective of scale and location (sludge vs. no sludge) with a resulting similar variance. Elements like Cd, Cr, Mg, Na, Ni, Sr, and V have a variance independent of location but are dependent on scale. Other elements, Ba, Be, Co, Cu, K, Mn, P, Pb, S, and Zn, have a variance that depends on both scale and location.
Field Calibration and Monitoring of Soil‐Water Content with Fiberglass Electrical Resistance Sensors
Authors: Seyfried M. S. 
Published: July 2010

AbstractElectrical resistance sensors, combined with data acquisition systems, offer a relatively inexpensive means of continuously monitoring soil‐water content (θ) at barely accessible remote sites. Fiberglass resistance sensors respond across the range of θ but require calibration. With field calibration, site‐specific soil conditions are implicitly accounted for, but calibration results have not been presented in the literature. The objectives of this study were to determine the accuracy and precision of field‐calibrated fiberglass resistance sensors and to demonstrate their application to monitoring at remote sites. Time domain reflectometry (TDR) was used for calibration. Sixteen individual sensor‐TDR calibrations and one overall calibration combining all measurements showed a strong log‐linear relationship between TDR‐measured θ and sensor‐measured resistance. Individual calibration 80% confidence intervals ranged from 0.02 to 0.045 m3 m−3. Calibration statistics did not appreciably drift during the study. These results, and subsequent measurements, were unaffected by soil freezing, indicating that the sensors respond to liquid water content. The overall calibration 80% confidence interval was 0.065 m3 m−3, due largely to high variability among sensors. However, changes in θ could be estimated with reasonably accuracy. Most (73%) of the resistance measurements made the year after calibration were within ±0.05 m3 m−3 of the TDR‐measured value. Sensor response time was shown to be within the 1‐h measurement interval. In this study, field‐calibrated fiberglass resistance sensors provided reasonably accurate estimates of θ at a high level of spatial and temporal resolution.
Stripper for Bubble‐Free Tensiometry
Authors: Miller Edward E. , Salehzadeh Amir 
Published: July 2010

AbstractUnwanted formation of air bubbles in the liquid water inside soil water tensiometers has always been a major nuisance afflicting this simple, fast, and accurate device. The stripper, a plastic wall (usually just a tubing wall) between the tensiometer water and a wet vacuum (containing some droplets of liquid water), strips any dissolved air out of this water. Bubbles cannot grow, they will shrink and disappear, unless the water pressure inside the tensiometer is less than the vapor pressure of water (at the ambient temperature). Choices of desirable plastic materials and other considerations are based on 7 yr of development and employment of this method.
Characterization of Carbonaceous Adsorbents by Soil Fulvic and Humic Acid Adsorption
Authors: Johns M. M. , Skogley E. O. , Inskeep W. P. 
Published: July 2010

AbstractSix porous carbonaceous adsorbents, selective for nonpolar organic adsorbates, were evaluated for dissolved soil humic adsorption and testing. Amberlite XAD 8 resin was similarly tested. Soil fulvic (FA) and humic (HA) acids were used as models for naturally occurring dissolved organic C in soil. The adsorbents were tightly packed as spherical capsules identical to previous studies using ion exchange resins for soil adsorption of plant nutrients. Static or passive adsorption from solution was applied. Kinetic studies (0–264 or 0–336 h) indicated a high initial adsorption rate followed by slower adsorption, common for porous adsorbents. Intraparticle diffusion was rate limiting. Adsorption differences between adsorbents are probably caused by molecular‐size exclusion effects due to pore size. The capsules of Carboxen‐Carbotrap resin mixture were capable of doubling adsorption, requiring no additional time, in response to doubling the FA (43–85 mg C L−1) or HA (46–90 mg C L−1) concentration. This effect was seen across the whole adsorption‐time range. The constant partitioning isotherm model described adsorption, indicating linear adsorption (r2 > 0.96, P < 0.01) with temperatures ranging from 13 to 50 °C, at pH 7.0, and within the concentration ranges of FA (9–126 mg C L−1) and HA (11–138 mg C L−1). This suggests a usefulness for these adsorbents at neutral pH and typical temperatures in waters for dissolved humic adsorption. Subsequently, initial solution concentrations of FA and HA were predicted from resin‐extractable C, indicating a potential for quantifying humic concentrations in solutions. Under identical conditions, XAD 8 resin did not demonstrate the testing attributes found with these carbonaceous adsorbents.
Residual Effects of No‐Till Crop Residues on Corn Yield and Nitrogen Uptake
Authors: Maskina M. S. , Power J. F. , Doran J. W. , Wilhelm W. W. 
Published: July 2010

AbstractThe residual effects of crop residues on N availability and crop growth are largely unknown. A field experiment was conducted from 1986 through 1988 at Lincoln, NE, to determine the residual effects on no‐till corn (Zea mays L.) production and N uptake of 0, 50, 100, and 150% of the amount of crop residues produced by the previous crop during the previous 5 yr. These effects were evaluated with and without tillage (disking), N fertilizer (60 kg N ha−1), and hairy vetch (Vicia villosa Roth ssp. villosa, ‘Madison’) winter cover crop. Increasing the previous crop residue rate increased organic C, total N, and NO3‐N in the upper 30 cm of soil as much as 10, 12, and 66%, respectively. Growth and N uptake by corn (3‐yr average) generally increased as previous residue rate increased. Corn grain and stover production was 17 and 25% greater for the highest compared with the lowest previous residue rate. Uptake of indigenous soil N, but not fertilizer N, also increased as previous residue rate increased. Cover crops generally increased growth and N uptake with no fertilizer, but had little effect with N fertilizer. Soil properties, crop growth, and N uptake generally were not affected by tillage or interactions among the variables. These results indicate that increasing no‐till crop residue rates increased the capability of this soil to provide N to growing crops for many years. It appears this effect is somewhat self‐perpetuating.
Water and Chemical Transport through Long‐Term No‐Till and Plowed Soils
Authors: Granovsky A. V. , McCoy E. L. , Dick W. A. , Shipitalo M. J. , Edwards W. M. 
Published: July 2010

AbstractFlow in soil macropores has been implicated as a mechanism for accelerated movement of agrichemicals into groundwater under conservation tillage practices. Strontium bromide hexahydrate, atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5 triazine), and alachlor (2‐chloro‐2′‐6′‐diethyl‐N‐[methoxymethyl]‐acetanilide) were surface applied to 18 undisturbed 0.3 by 0.3 by 0.3 m soil blocks collected from three Ohio soils subject to long‐term no‐till (NT) and moldboard plowing (MP). Two 30‐mm rains were applied to the block surface, and leachate was collected from 64 cells at the bottom of each block. Leachate volume, amount of chemicals leached, and visible pore area on bottom surfaces were determined for each cell. Semivariograms of cell leachate volumes revealed that water flow in both NT and MP soils is spatially uncorrelated at a scale of 30 to 300 mm. Principal component analysis at the cell level demonstrated that water flow in both NT and MP blocks followed preferential pathways. The NT blocks transmitted larger water volumes and chemical amounts than MP blocks; however, differences were rarely significant. Principal component analysis of transport in individual blocks suggested that the tillage differences resulted from a higher proportion of strongly preferential pathways in NT blocks. Discriminant analysis yielded significant separation in the soil hydraulic behavior as influenced by tillage and demonstrated the interaction in this behavior between soil type and tillage treatment. It has become clearer that rainfall timing and intensity following chemical application may overshadow tillage effects on water and chemical transport in soils.