bluuebunny/crossref_metadata_2025_split huggingface dataset:
Weed Population and Crop Yield Response to Recommendations from a Weed Control Decision Aid
Authors: Hoffman Melinda L. , Buhler Douglas D. , Owen Micheal D. K. 
Published: July 2010

AbstractSelecting among the diverse options available to manage weeds requires varied knowledge. This study field‐tested the performance of a decision aid model that integrates biological and economic factors to make weed control recommendations. The model was parameterized using data from the literature and subjected to sensitivity analysis. Tactics generated from the resulting model were compared with standard‐herbicide weed control in continuous corn (Zea mays L.) having a long‐term history of various tillage and herbicide application regimes. The model recommended preemergent and postemergent weed control based on weed seed and weed seedling densities, respectively. Using standard‐herbicide weed control resulted in fewer weed seeds in the soil each year compared with model‐based weed control. Variation among model‐based weed control treatments applied to plots with different management histories was eliminated over the course of the study as weed populations shifted in response to weed control practices. The result was a 98% relative abundance of foxtail (Setaria spp.) seedlings after 3 yr of model‐based treatments, compared with 70% in standard‐herbicide treatments. In 1994, the model reduced herbicide use and weed control treatment costs, but often reduced corn yields and net economic returns. In 1995, model‐based treatments maintained or increased corn yields and net returns. In 1996, however, model‐based treatments consistently reduced corn yields and net returns. Variability in control treatment effectiveness and weed‐crop interaction greatly affected the performance of the model. The use of decision‐aid models in weed management is still a developing technology. Interactions of the weed seed bank, weed emergence, treatment effectiveness, weed‐crop interference, and environmental conditions are very complex. The model could become a valuable tool for producers if consistency of weed control were improved by better understanding and modeling of threshold levels and accounting for weed seed production and by adding data on weed emergence, seed production, yield loss, and control efficacy.
Effect of Phosphate Source, Lime, and Time of Phosphate Application on Absorption of Applied Phosphorus by Plants
Authors: Chin N. L. , Ray H. E. , Caldwell A. C. , Hustrulid A. 
Published: July 2010

AbstractEffects of P source, rate of liming, and time of contact between fertilizer and soil on the availability and uptake by plants of phosphatic fertilizers applied to several Minnesota soils have been studied in greenhouse experiments.Monocalcium phosphate resulted in significantly higher yields and lower P contents of wheat than dicalcium phosphate, and was more available to both wheat and alfalfa.Alfalfa yields generally increased with an increase in the rate of liming. Liming had no apparent effect on the total P content of wheat or alfalfa, but the uptake by alfalfa of P from applied monocalcium phosphate was increased by the 4‐ton per acre rate of lime application. With both phosphate sources, alfalfa yields were highest on the alkaline soils, and lowest on an acid soil.Time of phosphate application had no consistent effect on growth rate or dry matter production of oats, although yield responses to phosphate fertilization were obtained on four soils. Phosphorus content of oats was generally increased when fertilizer was applied ahead of the planting date. Availability of applied phosphate tended to decrease on two high pH soils when fertilizer was applied 20 days or more ahead of planting.
Rate of Potassium Release from Fixed and Native Forms
Authors: Ellis Boyd G. , Mortland M. M. 
Published: July 2010

AbstractThe rate of release of K from fixed and native forms was compared utilizing a biotite‐vermiculite system. Although X‐ray diffraction patterns of oriented aggregates showed little difference between native biotite and weathered biotite containing fixed K, there was a marked difference in the rates of K release from the two materials. The release from native biotite was maintained at nearly a constant rate while approximately 50% of the K was removed, whereas with the fixed forms, rate of release decreased with time. The relationship between the logarithm of the rate of release and time was linear. The slopes of these curves were directly related to the extent of weathering which the weathered biotite had undergone before being subjected to the fixation reaction. The ease of release of fixed K therefore appears to be a function of the extent of weathering of the mica. This may be the result of loss of charge in the mineral during weathering.
Water Retention by Capillary Forces in an Ideal Soil
Authors: Waldron L. J. , McMurdie J. L. , Vomocil J. A. 
Published: July 2010

AbstractIn a system of air, water and solid spheres of uniform size the water content by volume may be expressed as a function of the pressure drop across an air‐water interface. Such an expression has been obtained by R. A. Fisher (1926).The validity of the Fisher theory was tested by making water extractions from saturated packs of equal size (monodisperse) glass beads. The extractions were made by means of pressure plate, centrifuge, osmotic solution and pressure membrane techniques. The glass spheres were Minnesota Mining and Manufacturing Co. “Superbrite” glass beads of 51, 99, and 203µ diameter.The data show that at all values of suction the amount of water retained by the pack of glass beads greatly exceeds the amount predicted by the Fisher capillary theory.This result indicates that a mechanism in addition to the pressure drop across the air‐water interface is involved in the retention of water in coarse‐grained, “noninteracting” materials. The lack of agreement may be a consequence of the omission of an adsorptive mechanism in this application of capillary theory.
A Comparison of Tree Responses to Fertilizers in Field and Pot Experiments
Authors: Mead D. J. , Pritchett W. L. 
Published: July 2010

AbstractEight uniform fertilizer experiments with Pinus elliottii Engelm. were established in the field between 1959–1962 on six soils ranging from excessively drained fine sands to poorly drained sandy loams. Soils from these experiments were used in pot tests, following similar treatments. Seedlings were grown for 8 months. No single measure of seedling response to treatments (height, diameter at soil surface, dry weight of tops, total dry weight) consistently correlated with field responses, expressed in terms of average tree height. There were large differences between field and greenhouse experiments in both type and degree of response obtained from the various soils. The best correlation (r = 0.66) was between seedling total dry weight and tree height at age 7. Height of greenhouse seedlings was the poorest method of those tested for predicting field response. All results from pot experiments were more poorly correlated with tree heights in the field after 3 years than after 7 years. The role of greenhouse experiments in studying deficiency symptoms and as a diagnostic tool for determining limiting nutrients is well recognized, but results must be used with caution for predicting magnitude of fertilizer response in the field.
Physical and Chemical Properties of the Forest Floor in Birch and Aspen Stands in Interior Alaska
Authors: Van Cleve Keith , Noonan Laraine L. 
Published: July 2010

AbstractThis study was conducted to establish the mass and nutrient status of the forest floor in quaking aspen (Populus tremuloides Michx.) and paper birch (Betula papyrifera Marsh.) forests in interior Alaska. Results of this investigation show that aspen forests have a greater mass of organic matter and nutrient elements in the forest floor than birch forests. The more favorable base status in aspen forest floors is reflected in higher pH and lower exchangeable hydrogen than encountered in birch forest floors. Increasing degree of organic matter decomposition in the forest floor of both vegetation types (L layer > F layer > H layer) is associated with increased N content and cation exchange capacity of the organic matter in the respective layers.
Assessing Boron Needs for Improving Peanut Yield and Quality
Authors: Hill W. E. , Morrill L. G. 
Published: July 2010

AbstractThree experiments were conducted to determine requirements of boron (B) for Spanish peanuts (Arachis hypogaea); (i) three rates of B were applied in solution to soil surfaces at 17 field locations, (ii) two rates of B were applied to soil at various stages of growth, and (iii) four B carriers were compared. Soil samples were collected at planting time. Leaf and petiole samples were collected 30 and 60 days after planting. The relationship of the occurrence of internal damage to initial soil B levels and concentration of B in plant tissue were evaluated. The effects of time, rate, and B carrier were also compared.Boron deficiency was found in more than 50% of the field locations. Boron application did not increase yields of peanuts or improve seed quality as measured by yield of sound mature kernels. The occurrence of internal damage from B deficiency (IDB) was shown to be related to hot‐water‐soluble soil B and to B content in young leaves and petioles. No IDB was found at locations with a hot‐water‐soluble soil B level > 0.15 ppm. Peanuts from plants with B concentration in young leaf tissue between 26 to 30 ppm at 30 and 60 days after planting were free of IDB. Boron applied as late as 60 days after planting was effective in eliminating IDB. No difference in the effectiveness of the four B carriers was found.
Depth Distribution and Seasonal Populations of Mesquite‐Nodulating Rhizobia in Warm Desert Ecosystems
Authors: Jenkins Michael B. , Virginia Ross A. , Jarrell Wesley M. 
Published: July 2010

AbstractDeeply rooted woody legumes are common in desert ecosystems yet little is known about the distribution of their rhizobial symbionts in relation to their roots and soil properties of the systems. The distribution of mesquite (Prosopis glandulosa Torr.)‐nodulating rhizobia was investigated to depths of 13 m in warm desert ecosystems. Soils were collected under mesquite from sand dune and playa ecosystems in the California Sonoran Desert, and from sand dune, playa, arroyo, and grassland ecosystems in the Chihuahuan Desert of southern New Mexico. A Larrea tridentata (DC.) Coville (creosote bush) ecosystem in New Mexico, containing no mesquite, was sampled as a reference. Three intact soil cores from each ecosystem were removed during the winter, spring, and fall from the New Mexico sites, and the winter from the California sites. Significant rhizobial population densities were measured in soil from 1‐ to 4‐m depths at the sand dune, arroyo, and playa ecosystems. At the playa ecosystem in New Mexico population densities > 105 cells kg−1 were measured in soils from 8‐m depth, and root nodules containing rhizobia were recovered in soil samples from 3‐, 4‐, and 7‐m depths. Multipleregression analysis of rhizobial concentration against soil NH4‐N, PO4‐P, electrical conductivity, and gravimetric water content indicated that no single soil factor was related significantly to rhizobial concentration across the ecosystems. Rhizobial densities varied with season in the dune and arroyo ecosystems. In these desert ecosystems significant rhizobial populations, root nodules, and presumably symbiotic N2 fixation occur at soil depths rarely studied.
Modeling Magnesium Uptake from an Acid Soil. II. Barber‐Cushman Model
Authors: Rengel Z. , Robinson D. L. 
Published: July 2010

AbstractA better understanding of the processes that are involved in the absorption of Mg may lead to improved management practices to avoid high grass tetany potential of forage. Two ryegrass (Lolium multiflorum Lam.) cultivars were grown in a greenhouse on an acid Stough soil (a coarse‐loamy, siliceous, thermic Fragiaquic Paleudult) amended with three rates each of CaO and MgCl2. Linear, lime‐rate‐dependent relationships between exchangeable and soil‐solution Mg were found. The slopes of these relationships (Mg buffer power) were 0.68, 1.31, and 1.21 for lime rates 0, 1, and 3 g kg−1, respectively. The Barber‐Cushman nutrient‐uptake model consistently overpredicted observed Mg uptake by 1.15 to 1.70 times, depending on the Mg application rate. Model calculations showed accumulation of Mg at the root surface. Sensitivity analyses revealed that large values of maximal net Mg influx (Imax) were the reason for overprediction of Mg uptake. Using input parameters based on soil‐solution Mg activities lowered the overprediction to 1.10 to 1.61 times the observed uptake. A major obstacle to using the Barber‐Cushman model for predicting Mg uptake is the lack of information about kinetic parameters of plant uptake from soil solution.
Air Pressure Fluctuations in a Prairie Soil
Authors: Renault Pierre , Mohrath Dalila , Gaudu Jean‐Claude , Fumanal Jean‐Claude 
Published: July 2010

AbstractThe influence of air convection on soil aeration has not been investigated in great detail. A study was conducted to measure air pressure changes by depth in the first 2 m of a prairie soil that was known for its denitrification properties. An absolute air pressure probe was used to measure air pressure fluctuations at the soil surface and newly designed differential air pressure probes were placed at depths of 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1, 1.5, and 2 m. A procedure of in situ recalibration was used every 6 or 7 wk for these probes. At the same depths, capacitive probes and thermocouples measured the volumetric water content and temperature, respectively. The bulk density profile, water table level, and rainfall amounts were recorded. The atmospheric pressure ranged between 97 000 and 101 000 Pa during the experiment. The signal drift of the air pressure probes was negligible for four of the probes and <50 Pa for the others. The accuracy of the measurements with signal drift compensation was superior to 10 Pa. Differences of air pressure between the soil at the surface and at depth may be >2000 Pa. These differences, which are not necessarily linked to the depth, are probably due to soil heterogeneities and generally to water infiltration. Air pressure seemed to level out quickly when the air‐filled pore space was continuous. This generally prevented “dephasing‐amortization” effects. When the air‐filled pore space was discontinuous, differential air pressures depended simultaneously on the atmospheric pressure and temperature fluctuations.
Changes in Soil Water Retention Curves Due to Tillage and Natural Reconsolidation
Authors: Ahuja L. R. , Fiedler F. , Dunn G. H. , Benjamin J. G. , Garrison A. 
Published: July 2010

AbstractChanges in soil water retention of the surface soil brought about by tillage can significantly alter the amount of rain water that infiltrates into the root zone and is available for plant growth. Soil tillage generally increases porosity and changes the pore‐size distribution, leading to changes in the soil water retention curve and hydraulic conductivities. The objective of this study was to investigate some simple ways of estimating the soil water retention curve of a tilled soil from that of an untilled soil, knowing the change in soil porosity or bulk density due to tillage. The study of literature and empirical analysis of the available data indicated: (i) under field conditions the tillage did not significantly change the air‐entry value of the soil; (ii) tillage increased the absolute value of the slope of the log‐log relationship below the air‐entry value; and (iii) the changes due to tillage in the retention curve occurred only in the larger pore‐size range, approximately between the air‐entry pressure head value and 10 times the air‐entry value. Assuming these observations hold in general, two simple methods of estimating the water retention curve of a tilled soil from that of its untilled condition are proposed. The first method is a simple imposition of the Brooks and Corey function between the air‐entry value and 10 times this value. The second method assumes that the change in soil water content at a given pressure head in the above range of pressure heads was inversely proportional to the value of the pressure head. The tests on four pairs of measured water retention curves on three different soils showed that these methods provided good approximations.
Robert Brown on Pterocymbium (Sterculiaceae)
Authors: MABBERLEY D J 
Published: July 2010

SUMMARY Robert Brown's use of pamphlets as a medium for disseminating his work is explained and the necessary resultant amendments in nomenclatural citation pointed out. The pamphlets associated with Horsfield's Plantae javanicae rariores are described, the existence of the second of these, Pterocymbium, having come to light in only 1984. It was published in June 1844, some five months before the text appeared in Plantae javanicae rariores under the general supervision of Bennett. New names of genera and species (largely referable to Sterculiaceae, but also Euphorbiaceae) are attributable to Brown alone.
A preliminary note on the publication dates of H. C. Andrews' Coloured engravings of heaths (1794–1830)
Authors: CLEEVELY* R. J. , OLIVER* E. G. H. 
Published: July 2010

ABSTRACT: An account is given of this major work on Cape heaths (Erica spp) produced during a period that such plants were fashionable. The first volume (1794–1802), originally published in parts, contained the author's explanation and a dissertation on the history and cultivation of these species. None of the plates in its four volumes was numbered so that subscribers could make their own arrangements, but both alphabetical and systematic lists were provided. The copyright acts of that period required the date of issue to be stated, and lists of these help to establish the dates of publication of the names of the new species described. Examination of the engraved dates and other evidence indicates that the following dates can be applied to Coloured engravings of heaths: original parts 1794–1802, volume I “1802”, volume II “1805x201D;, volume III “1809x201D; and volume IV 1810–1830, but these are subject to further work. These dates have also been used to infer the probable contents of the earlier parts which the discovery of a set of the original 23 numbers has since confirmed.
Effect of exercise intervention on thigh muscle volume and anatomical cross‐sectional areas—Quantitative assessment using MRI
Authors: Hudelmaier Martin , Wirth Wolfgang , Himmer Maria , Ring‐Dimitriou Susanne , Sänger Alexandra , Eckstein Felix 
Published: July 2010

AbstractThe objective of this study was to evaluate the location‐specific magnitudes of an exercise intervention on thigh muscle volume and anatomical cross‐sectional area, using MRI. Forty one untrained women participated in strength, endurance, or autogenic training for 12 weeks. Axial MR images of the thigh were acquired before and after the intervention, using a T1‐weighted turbo‐spin‐echo sequence (10 mm sections, 0.78 mm in‐plane resolution). The extensor, flexor, adductor, and sartorius muscles were segmented between the femoral neck and the rectus femoris tendon. Muscle volumes were determined, and anatomical cross‐sectional areas were derived from 3D reconstructions at 10% (proximal‐to‐distal) intervals. With strength training, the volume of the extensors (+3.1%), flexors (+3.5%), and adductors (+3.9%) increased significantly (P < 0.05) between baseline and follow‐up, and with endurance training, the volume of the extensor (+3.7%) and sartorius (+5.1%) increased significantly (P < 0.05). No relevant or statistically significant change was observed with autogenic training. The greatest standardized response means were observed for the anatomical cross‐sectional area in the proximal aspect (10–30%) of the thigh and generally exceeded those for muscle volumes. The study shows that MRI can be used to monitor location‐specific effects of exercise intervention on muscle cross‐sectional areas, with the proximal aspect of the thigh muscles being most responsive. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Compositional and Antioxidant Activity Analysis of Zanthoxylum bungeanum Seed Oil Obtained by Supercritical CO2 Fluid Extraction
Authors: Xia Lian , You Jinmao , Li Guoliang , Sun Zhiwei , Suo Yourui 
Published: July 2010

AbstractSupercritical CO2 fluid extraction (SFE‐CO2) of Zanthoxylum bungeanum (Z. bungeanum) seed oil was investigated. To optimize the SFE process, three‐level Box‐Behnken factorial design and response surface methodology (RSM) were applied to optimize the extraction conditions, including pressure, temperature and amount of modifier. The optimum conditions were as follows: extraction pressure, 29.28 MPa; extraction temperature, 41.19 °C; and the added amount of modifier, 10.94%. The experimental results showed that the maximum extraction yield was 21.85 ± 0.23% (n = 3) under the proposed conditions. The compositional analysis of Z. bungeanum seed oil was performed by HPLC‐FLD‐MS using a new labeling reagent of 2‐(11H‐benzo[a]carbazol‐11‐yl)‐ethyl‐4‐methyl benzenesulfonate (BCETS). The results indicated that the Z. bungeanum seed oil contained mainly unsaturated fatty acids, including C18:3, C22:6, C20:4, C18:2, C18:1 and C20:1, which accounted for 84.0% (mass percentage) of the total amount. The antioxidant activity of seed oil obtained by Box‐Behnken design concerning the DPPH radical was investigated, and this indicated that the pressure and the amount of added modifier had positive effects on the antioxidant activity, but the effect of the temperature elevation is complicated, depending on the nature of the extracted contents.
Can social support protect bullied adolescents from adverse outcomes? A prospective study on the effects of bullying on the educational achievement and mental health of adolescents at secondary schools in East London
Authors: Rothon Catherine , Head Jenny , Klineberg Emily , Stansfeld Stephen 
Published: July 2010

ABSTRACTThis paper investigates the extent to which social support can have a buffering effect against the potentially adverse consequences of bullying on school achievement and mental health. It uses a representative multiethnic sample of adolescents attending East London secondary schools in three boroughs. Bullied adolescents were less likely to achieve the appropriate academic achievement benchmark for their age group and bullied boys (but not girls) were more likely to exhibit depressive symptoms compared to those not bullied. High levels of social support from family were important in promoting good mental health. There was evidence that high levels of support from friends and moderate (but not high) family support was able to protect bullied adolescents from poor academic achievement. Support from friends and family was not sufficient to protect adolescents against mental health difficulties that they might face as a result of being bullied. More active intervention from schools is recommended.