bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting Mycorrhizal Dependency of Troyer Citrange on Glomus fasciculatus in California Citrus Soils and Nursery Mixes
Authors: Menge J. A. , Jarrell W. M. , Labanauskas C. K. , Ojala J. C. , Huszar C. , Johnson E. L. V. , Sibert D. 
Published: July 2010

AbstractIn a greenhouse experiment the mycorrhizal fungus, Glomus fasciculatus, significantly increased growth of Troyer citrange (Poncirus trifoliata L.) (TC) seedlings in 20 of 26 methylbromide‐fumigated citrus soils from southern California. Of the six soils in which G. fasciculatus provided no growth increase, two were greenhouse soils, three were nursery soils, and only one was a field soil. Glomus fasciculatus increased foliar P, K, and Cu concentrations and decreased foliar Mg and Na concentrations of TC grown in the majority of the 26 citrus soils. Foliar concentrations of P, K, Ca, Na, Zn, Mn, Cu, and Fe from either mycorrhizal or nonmycorrhizal TC could not be significantly correlated with the mycorrhizal dependency of TC in the soils studied. A positive correlation was observed between foliage concentrations of Mg in nonmycorrhizal TC and mycorrhizal dependency. Mycorrhizal dependency of TC was also positively correlated with soil pH and inversely correlated with extractable soil P (bicarbonate), Zn, Mn, Cu, percent organic matter, and cation exchange capacity. In the fumigated soils studied, it was highly probable that inoculations with G. fasciculatus would induce significant growth response in TC provided the soils had <34 ppm extractable P, 27 ppm extractable Mn, 12 ppm extractable Zn, or 3% organic matter. The magnitude of the mycorrhizal dependencies of TC on G. fasciculatus in the 26 citrus soils were accurately predicted with equations which used soil P, Mn, Zn, and also Cu and pH as independent variables.
The Role of the Western Harvester Ant (Pogonomyrmex occidentalis) in Soil Formation
Authors: Mandel Rolfe D. , Sorenson Curtis J. 
Published: July 2010

AbstractThe effects of harvester ants (Pogonomyrmex occidentalis) on the physical and chemical properties of soils were determined for 20 ant mounds in the semiarid subalpine region of south‐central Colorado. Comparisons of soil materials in mounds of active colonies with surrounding unaffected soils showed significant differences in particlesize distribution and concentrations of CaCO3, exchangeable K, Na, Mg, and total N. The activity of ants in the study area appears to affect less ground surface area than in more humid regions (1 to 10% of respective land areas by regional comparison). The ants also tend to rearrange particles preferentially in the sand fraction instead of in the finer fractions as recorded for more humid regions. However, their role in nutrient enrichment of mound soils is similar to that of different ant species in other regions. The soil alterations induced by P. occidentialis are favorable for plant growth, and the ant mounds may aid revegetation in disturbed areas.
Perched Water Tables on Hillsides in Western Oregon: I. Some Factors Affecting Their Development and Longevity
Authors: Hammermeister D. P. , Kling G. F. , Vomocil J. A. 
Published: July 2010

AbstractPerched water tables on hillsides located on the western border of the Willamette Valley in Oregon in some cases have the potential to transport pollutants from either domestic or agricultural sources downslope to streams, ponds, or reservoirs, resulting in the deterioration of the quality of these waters. In this paper, some factors responsible for the development and longevity of these potentially problem‐causing perched water tables on three hillsides were examined. Analyses of hydraulic conductivity data and the relationships between rainfall, soil water pressure potential, and time suggest that permeable rock below 110 cm rather than clayey B horizons is mainly responsible for the development of perched water tables on upper convex slope positions on two of these hillsides. The data also suggest that subsurface flow from the upper convex regions contributed significant amounts of water to the lower convex slope positions. Further, perched water tables developed more rapidly, to a greater extent, and lasted longer in upper horizons of a lower concave region of slope where a shallow perched water table was already present at the onset of rainfall. Finally, perched water tables did not develop in the upper horizons on a third hillside that had no impermeable regions in the soil or upper rock mantle.
Internal Energy Balance and the Richards Equation
Authors: Sposito Garrison , Chu Shu‐Yuan 
Published: July 2010

AbstractThe energy concept of soil water introduced by Buckingham and developed by Richards is employed to derive a differential balance equation for the partial specific internal energy of water in an unsaturated soil. This equation is shown to comprise both heat flux and chemical work terms, in correspondence with the first law of thermodynamics. For the case of isothermal water flow through a rigid, homogeneous soil, the balance law for internal energy reduces to the Richards Equation with the soil water matric potential as the dependent variable. This result, which does not require the conventional direct appeal to the law of mass balance, demonstrates that the energy concept of soil water provides a self‐consistent method for obtaining the Richards Equation. Either the energy balance concept or the traditional mass‐balance approach can be used to establish the macroscopic physical foundations of the Richards equation.
Nutrient Availability Under Trickle Irrigation: II. Mineral Nitrogen
Authors: Bacon P. E. , Davey B. G. 
Published: July 2010

AbstractThe effects of irrigation and fertilizer application on nitrate, nitrite, and ammonium concentration in a Chromic Luvisol were studied in an orchard that had been trickle irrigated for 5 years. Immediately before the first irrigation of the season, mean plot nitrate‐N was 5 ppm; 8 h of irrigation reduced this to 0.5 ppm. Nitrite concentration fell from 0.8 to 0.4 ppm in the same period. During irrigation ammonium concentration rose from 7.1 to 13.5 ppm (the average rate of increase being 0.8 ppm/h) in the surface 6‐cm depth of soil extending up to a distance varying from 30 to 65 cm from the outlet. There was no evidence that nitrate or nitrite accumulated at the A/B horizon boundary and it is likely that the loss was due to denitrification.Ammonium concentration decreased rapidly as the soil dried out and 8 h after the end of irrigation it had fallen from 13.5 to 8.5 ppm. As there was no change in the nitrate concentration in this region during the same 8‐h period the ammonium was being immobilized rather than nitrified. The only place where nitrification took place during the first 3‐d cycle was immediately below the fertilizer band at site D where nitrate concentration rose from 0 to 15 ppm in 3 d. Mean plot nitrate‐N at the end of the first cycle was 2.6 ppm. Some 32 cycles later at the beginning of the midseason 3‐d cycle nitrate‐N had fallen to 0.6 ppm. Neither nitrate nor nitrite varied with time during the midseason 3‐d cycle. Ammonium concentration rose significantly over the region extending from at least 12 cm below the surface under the outlet to the 3‐ to 6‐cm depth 65 cm away from the outlet. Over this volume of soil ammonium‐N increased from 3.9 to 19.4 ppm during irrigation. In the 4 h after the end of irrigation the ammonium concentration decreased and there was no significant difference between the pre‐ and post‐irrigation ammonium concentrations within the volume defined above. Apparently all the ammonium released during irrigation and not taken up by plants was immobilized by the soil microbial population. The amount of ammonium released was greater in the midseason (15.5 ppm) than in the first 3‐d cycle (6.4 ppm). Ammonium release rate during the midseason irrigation was 1.3 ppm N · h−1. There were no significant changes in nitrate, nitrite, or ammonium during the midseason 1‐d cycle.The results obtained for five 3‐d irrigation cycles in early summer again demonstrated that the decrease in nitrate during the irrigation cycle was accompanied by an increase in ammonium. The phenomena was part of a continuous cycle which increased the mineral nitrogen availability during the wet portion of every 3‐d cycle.
Characterization of Nutrient Transport Coefficients in Field‐grown Soybeans
Authors: Scott H. D. , Brewer D. W. 
Published: July 2010

AbstractA knowledge of nutrient translocation in plants is basic to an understanding of plant nutrition. Thus, a mathematical model was developed to describe nutrient translocation in a four‐compartment soil‐soybean system. Mass balance equations were used to describe the instantaneous rate of change in the amount of a given nutrient in the compartments assuming that the nutrients move at a rate that is proportional to the concentration of the compartment from which it flows. Dry weights and accumulations of N, K, Ca, and Mg in stems, leaves, and pods of ‘Lee 74’ soybeans (Glycine max. L. Merr.) grown on two soils and under two moisture regimes were used as inputs into the model.Two methods were formulated to describe dry weights and nutrient accumulations in the stems, leaves, and pods. The first method was based on linear vegetative growth of the stems and constant stem and leaf weights during reproductive growth. The second method was based on a statistical fit of the seasonal nutrient concentration in the stems and leaves. The experimental data were used to calculate nutrient uptake rates and transport coefficients during several intervals according to both methods.Nutrient uptake rates, crop growth rates, the stem‐to‐leaf transport coefficient (Ksl), and the stem‐to‐pod transport coefficient (Ksp) varied considerably during the season and were higher in those soybeans that were irrigated and grown on the clay soil. Of the nutrients studied N had the greatest uptake rate, Ksl, and Ksp.
Long‐term Effects of Manure on Soil Nitrogen, Phosphorus, Potassium, Sodium, Organic Matter, and Water Infiltration Rate
Authors: Meek Burl , Graham Lucy , Donovan Terry 
Published: July 2010

AbstractHigh rates of manure were added to field plots of a Holtville silty clay (Typic Torrifluvents) soil in an irrigated desert region, and their effects on the soils' chemical and physical properties were measured for 9 years.Manure applications resulted in large losses of nitrogen (N), increased potassium (K) levels, increased phosphorus (P) availability, increased water intake rates during the growing season, and an N mineralization rate of about 5% after the first year. At high rates of manure application only 42% of the N applied could be accounted for. One application of 180 t/ha of manure in 1971 doubled the NaHCO3‐extractable P levels in the soil in 1979 compared with that of plots that did not receive manure. The application of manure had only a small or no effect on the water intake rate when it was measured between cropping periods on plots that had been recently tilled, but differences were large when water intake rates were measured while the crop was growing. The increased water infiltration rates during the growing season would be important because of increased crop yields in areas affected by salinity.
Geostatistical Analysis of Soil Chemical Properties of Large Land Areas. II. Kriging
Authors: Yost R. S. , Uehara G. , Fox R. L. 
Published: July 2010

AbstractThe use of soil analyses to construct maps of soil properties and to identify areas of particular interest or requiring separate management, is important in soil science. Recent developments in geostatistics permit increased ability to summarize and interpret such soil analyses. Soil analyses from transects on the Island of Hawaii were used for estimating soil P sorption over the entire island by means of an optimal geostatistical technique called kriging. Displays of P sorption information obtained by kriging were compared with those obtained by a more common method of spline interpolation. The map of kriged points corresponded more closely with known soil behavior than did the spline map. Kriging further provided estimates of the reliability of the resulting map. Areas were identified where additional samples would be most useful in reducing the estimation variance which indicates map reliability. The necessity of considering nonstationarity and using universal kriging was evaluated. Universal kriging, either by prior polynomial trend removal or by local polynomial trend removal during estimation, was not beneficial in spite of widely varying P sorption and a significant polynomial trend in the data. Results suggest ordinary kriging is useful in summarizing and interpreting soil analyses and that ordinary kriging seems quite robust to certain degrees of nonstationarity.
Positive Permanent Charge in Oxisols
Authors: Tessens E. , Zauyah Siti 
Published: July 2010

AbstractThe existences of a positive permanent charge can be inferred from charge characteristics of highly weathered tropical soils; it was found to be related to isomorphous substitution of Ti(IV) for Fe(III) in iron oxides. Comparable near‐constant values were found from anion adsorption at pH 7.0 to 9.0. It was concluded that both positive and negative permanent charge can coexist in the same soil.
Potential for Nutrient Depletion by Short Rotation Harvest of Sweetgum
Authors: Francis John K. , Baker James B. 
Published: July 2010

AbstractThis study was conducted to determine if short rotation harvests of sweetgum (Liquidambar styraciflua L.) could deplete a clayey soil of nutrients. Sixteen trees in late summer and another 16 in early winter were harvested to determine the nutrient distribution in an 11‐year‐old plantation. Nutrient removal for several harvesting alternatives were projected. Nutrient removal would be in the order of August whole‐tree chip > November whole‐tree chip ≫ harvest of bole with bark > harvest of bolewood only. Nutrient losses through less intensive harvests are made up for by nutrient additions in rainfall. Even at the high rate of removal incurred with summer whole‐tree chipping, hundreds of 11‐year rotations would be necessary to deplete the soil of nutrients.
Design for a Field Sprinkler Infiltrometer
Authors: Zegelin S. J. , White I. 
Published: July 2010

AbstractA sprinkler infiltrometer using air pressure to drive water through an interchangeable nozzle onto a field plot has been designed and tested for use in infiltration and redistribution studies. Application rates with uniform distribution are selected by electronically pulsing a solenoid valve between the pressurized water supply and the nozzle. A field test demonstrated the use of the infiltrometer in measuring the time to incipient ponding and the development of the water content profile.
On the Use of the Langmuir Equation in the Interpretation of “Adsorption” Phenomena: II. The “Two‐Surface” Langmuir Equation
Authors: Sposito Garrison 
Published: July 2010

AbstractA rigorous, mathematical representation of a sorption isotherm as a Stieltjes transform is employed to prove a theorem about the “two‐surface” Langmuir equation. This theorem states that, if the distribution coefficient for an ion sorbed by a soil is a finite, decreasing function of the amount sorbed, q, and extrapolates to zero at some finite value of q, then the sorption isotherm can always be represented mathematically by a two‐surface Langmuir equation. Since the proof of this theorem does not depend on the chemical mechanism of ion sorption, it follows that the adjustable parameters in the two‐surface Langmuir equation cannot be interpreted in terms of surface reactions without additional, independent evidence that only adsorption on two kinds of surface site actually is involved in the ion sorption reaction.
Comparison of the Abilities of Hydroxamic, Synthetic, and Other Natural Organic Acids to Chelate Iron and Other Ions in Nutrient Solution
Authors: Cline Gary R. , Powell P. E. , Szaniszlo P. J. , Reid C. P. P. 
Published: July 2010

AbstractChelation modeling was used to predict the abilities of hydroxamate siderophores (HS) and other natural organic acids to chelate Fe and other ions in a modified Hoagland nutrient solution as a function of pH (4.0–10.0). Experimentally determined levels of chelated Fe (pH 5.0–10.0) agreed with our predicted results and with values previously predicted for EDTA (ethylenediaminetetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), and EDDHA [ethylenediamine di(o‐hydroxyphenylacetic) acid].The natural HS, Desferrioxamine B (DFOB), and an unknown mixture of HS isolated from the ectomycorrhizal fungus Boletus edulis, remained fully chelated with Fe at all values of pH. Modeling predicted DFOB to be 99.9% chelated with Fe even in nutrient solution of pH 10.0. No significant chelation of Fe was measured or predicted above pH 6.0 for malate, malonate, oxalate, succinate, α‐ketoglutarate, or pyruvate. Only 4% of citrate was chelated with Fe at pHs 6.0 and 6.4 as determined by direct measurement and computer modeling, respectively.Solubility constants, derived for Fe(OH)3 (amorphous) (amorph.) and FePO4 (amorph.), indicated that FePO4 (amorph.) can control Fe solubility in nutrient solutions of low pH and reduce the ability of ligands to chelate Fe, relative to conditions in which Fe solubility is governed by Fe(OH)3 (amorph.).Since our results indicate that microbially produced hydroxamate siderophores have a significant influence on Fe solubility, we discuss how such ligands could be of importance in the Fe nutrition of plants under natural soil conditions.
Denitrification in No‐Till and Plowed Soils
Authors: Rice Charles W. , Smith M. Scott 
Published: July 2010

AbstractNo‐till and plowed soils were compared with regard to denitrifying activity. To assay denitrification with minimal physical disruption of the soil, an important consideration in the study of tillage effects, a procedure was developed employing acetylene (C2H2) inhibition of nitrous oxide (N2O) reduction in intact soil cores. This approach and a short‐term, anaerobic soil slurry assay were consistent in indicating greater denitrifying activity in no‐till than in plowed Maury silt loam soil. In the intact core assay, ratios of no‐till to plowed soil activity were >1 on all sampling dates, and were as high as 77. Intact cores from a Crider (Typic Paleudalfs) soil showed a similar tillage effect, but tillage had inconsistent effects on both soil water content and denitrifying activity in a Tilsit (Typic Fragiudults) soil. It is suggested that the generally higher soil moisture contents observed in no‐till soils, rather than tillage per se, are primarily responsible for higher denitrifying activity. Enhanced denitrification may account, in part, for the lower soil NO‐3 concentrations and higher N fertilizer requirements sometimes reported for no‐till soils.
Estimating Saturated Hydraulic Conductivity from Soil Morphology
Authors: McKeague J. A. , Wang C. , Topp G. C. 
Published: July 2010

AbstractGuidelines were developed for estimating the saturated hydraulic conductivity (Ksat) class of soil horizons from observations of soil morphology by checking estimates against Ksat values measured in the field by an air entry permeameter. For 78 soil horizons ranging in texture from sand to clay, the estimated Ksat class (of eight classes) was the same as the measured class for 45% and within one class of the measured class for 87% of the horizons. Some horizons fell into each of the classes defined, from H1 (>50 cm/h) to L3 (<0.017 cm/h). The major factors contributing to high Ksat values were abundant biopores, textures coarser than loamy fine sand, and strong, fine to medium blocky structure. The lowest values were associated with clayey horizons that had been compressed or puddled by cultivation. Useful estimates of Ksat can be made during soil survey by careful observations of morphology and frequent checks of estimates against measured values.
Comparison of Fall and Spring Application of 15N‐Labeled Urea to Douglas‐Fir: I. Growth Response and Nitrogen Levels in Foliage and Soil
Authors: Heilman P. E. , Dao Thanh , Cheng H. H. , Webster S. R. , Harper S. S. 
Published: July 2010

AbstractMovement, transformation, and recovery of fertilizer N by analysis of soil and foliage of seven‐ and nine‐year‐old Douglas‐fir were followed over a two‐year period at two relatively high quality sites in western Washington. Urea fertilizer labeled at approximately 8 atom percent 15N was applied at 224 kg N/ha at the end of November 1977 and in late April 1978. High rainfall followed the fall fertilizer treatment and low rainfall occurred after the spring treatment. Differences in variability in fertilizer recovery, fertilizer movement, and tree response to fertilization appeared to be related to differences in rainfall patterns shortly after fertilization. On the average, fall fertilization gave better volume growth response than spring fertilization, but substantial variation in response was observed between sites and season of application.Fertilizer N did not appear in substantial concentrations in foliage until after 6 weeks, with high levels of 15N still evident in foliage after 2 years. With the spring treatment, fertilizer N could have appeared earlier in the newly formed foliage, but this foliage was not sampled until August. The increase in total percent N in foliage lasted only about 1 year following spring treatment and 15 months following fall treatment. Peak concentrations of ammonium N in soil occurred in samples collected 9 d to 3 weeks after fertilization. Ammonium content in the soil declined rapidly and approached control levels at 24 weeks. However, at one site, nitrification was active and relatively high nitrate content was present in the soil at 24 weeks.Recovery of fertilizer N from analysis of soil was variable, averaging 59 ± 10% of the application at 3 d and about 100% between 9 d to 3 weeks. After two growing seasons, recovery from analysis of soil averaged only 38 ± 6%. Substantial increases in mineral N levels were observed in the soil beyond the quantity applied as fertilizer (the priming effect). Data from early samples of foliage showed increased concentration of N possibly resulting from this phenomenon. However, after the middle of the first growing season following treatment, no increased concentration of N in foliage from soil organic matter was evident.
Quantitative Evaluation of Water Adsorption on Soil Clays
Authors: Karathanasis A. D. , Hajek B. F. 
Published: July 2010

AbstractQuantitative water adsorption determinations were obtained from clay fractions of soil and sedimentary samples by both adsorption isotherms and low temperature thermogravimetry and differential scanning calorimetry techniques. Isotherms at 35°C were obtained with a sealed evacuated quartz spring system and a cathetometer. The weight of water required for monolayer coverage was calculated by application of BET and Langmuir equations. Surface areas based on adsorption by the BET equation were more suitable than from Langmuir, especially when hydroxy‐interlayered or zeolite impurities were present. Quantifications of expanding 2:1 minerals by surface area, weight loss, and enthalpy methods compared favorably. Correlation coefficients comparing methods were high (r = 0.97) and average deviations were small (±3.9%). Water adsorbed by clays at 52% relative humidity was exactly double the monolayer BET value. Water vapor adsorption level for montmorillonitic clay fractions was always >9.0%. Monolayer adsorption limits between mixed and kaolinitic mineral classes ranged from 2.2 to 2.4%. These relationships indicate that water adsorption can be used to aid routine clay mineral analysis for classification purposes.