bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphorus Chemistry and Mineralogy in Excessively Fertilized Soils: Solubility Equilibria
Authors: Pierzynski G. M. , Logan T. J. , Traina S. J. 
Published: July 2010

AbstractEleven samples representing six soil series were selected for this study of excessively fertilized soils. Phosphorus sources included fertilizers, sewage sludges, and manures. The samples had Bray Pl extractable P levels ranging from 29 to 640 mg P/kg and 1:1 soil/water pH values ranging from 5.4 to 7.4 The equivalent of 25 g of dry soil and 50 mL of water were incubated at 298K. Samples were sacrificed for analysis periodically during the 130‐d test period. The activities of most ions, as estimated with GEOCHEM, were relatively constant throughout the course of the experiment. The concentrations of organic and inorganic C for samples that had been amended with sewage sludges or manures varied considerably during the course of the experiment. Samples that produced high supernatant pH values (>6.8) generally were more soluble than hydroxyapatite and less soluble than octacalcium phosphate and were slow in attaining constant ion activity products relative to the Ca phosphate minerals considered. Samples that produced low supernatant pH values (<6.8) indicated an equilibrium with the amorphous analog of variscite throughout the experiment.
Fluoro‐Aluminum Complexes on Model and Soil Exchangers
Authors: Anderson M. A. , Zelazny L. W. , Bertsch P. M. 
Published: July 2010

AbstractA number of investigators have suggested that complexes may exist as discrete species on the exchange phase and, thus, be important to a complete description of exchange reactions. Little evidence establishing the presence of complexes on the exchange phase has hitherto been provided, however. Adsorption experiments in which µM F solutions were equilibrated with K‐, Ca‐, and Al‐saturated cation‐exchange resins demonstrated substantial F removal to the Al‐saturated resin, with the adsorbed F quantitatively recovered with a single wash with 1.0 M NH4Cl, whereas no F removal was observed when either K or Ca occupied the exchange sites. Removal of both Al and F from Al‐F solutions equilibrated with K‐ and Ca‐saturated resins provided additional evidence for adsorption as fluoro‐Al complexes. Modeling of the competitive complexation‐exchange reactions with MINTEQA2 yielded results that under‐predicted net Al sorption in the presence of F, and thus also inaccurately predicted solution composition, by neglecting potential adsorption of fluoro‐Al complexes. Kaolinite (KGa‐2) samples also sorbed appreciable F, though both surface OH displacement and sorption to exchange‐phase Al were apparently responsible for the observed decrease in F solution concentrations. In the absence of exchange‐phase Al, however, all sorbed F was fixed against displacement by 1.0 M NH4Cl. Samples of a Fuquay soil (loamy, siliceous, thermic Arenic Plinthic Paleudult) profile from South Carolina were also extracted with water, 0.01 M CaCl2, and 1.0 M NH4Cl; no detectable F was found in the water extracts, while considerable F was solubilized in the CaCl2 and NH4Cl extracts, with NH4Cl‐extractable F being highly correlated with exchangeable Al (r2 = 0.98). These results suggest that part of the Al on the soil exchange phase may in fact exist as fluoro‐Al complexes, and also imply a role of exchange‐phase Al in regulating apparent F solubility within acid soils.
Decomposition of Wood‐Residue Amendments in Revegetated Bentonite Mine Spoils
Authors: Schuman G. E. , Belden S. E. 
Published: July 2010

AbstractRestoration of decomposition processes in revegetated mine spoils is important in ensuring the long‐term success of their reclamation. This study was conducted to determine the decomposition of ponderosa pine (Pinus ponderosa Laws) wood residue amendments in a revegetated saline‐sodic bentonite mine spoil. A buried‐litter‐bag technique was used to assess the effect of wood‐residue amendment and N‐fertilizer rates on the decomposition of wood residue in revegetated bentonite spoils. Decomposition differed significantly between years and averaged 8.8, 10.4, 16.1, and 25.3% after 1, 2, 3, and 5 yr, respectfully, across all wood‐residue treatments. Decomposition increased significantly as N‐fertilizer rates increased, averaging 10.6, 14.3, 18.8, and 20.8% over 5 yr for the 0, 2.5, 5.0, and 7.5 kg N Mg−1 of wood residue treatments, respectively. Wood‐residue amendment rate did not significantly influence decomposition, even though it significantly increased spoil water content. Decomposition processes appear to be proceeding despite the unfavorable physical and chemical characteristics of the spoil and should ensure the reclamation success of these disturbed ecosystems.
Comparisons of Humic Substances Extracted from Contiguous Alfisols and Mollisols of Southwestern Ohio
Authors: Novak J. M. , Smeck N.E. 
Published: July 2010

AbstractHumic and fulvic acids extracted from contiguous Alfisols and Mollisols were characterized to determine if any dissimilarities could be documented between humic substances extracted from soils formed under nearly identical environmental conditions, but belonging to different taxonomic classes. Comparisons of humic substances from two Alfisol‐Mollisol pairs, one from the Wisconsinan and one from the Illinoian till plain of southwestern Ohio, were based on wet chemical, infrared, and 13C cross‐polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy studies. Using 0.1 M NaOH, more humic substances were extracted from the Mollisols than the Alfisols, with the majority being humic acids. Small amounts of fulvic acids were recovered from all pedons. Data from infrared and 13C CPMAS NMR spectroscopy indicate that humic acids from both the Alfisols and Mollisols are dominated by alkyl‐substituted aromatic structures, followed by aliphatic, O‐substituted alkyl, carboxylic acid, and small amounts of carbonyl structures. Whereas 13C NMR spectroscopy data suggest Mollisol humic acids contain higher aromatic and carboxylic acid contents than those of the Alfisols, Alfisol humic acid spectra show more evidence for phenolic‐OH groups and lignin and lignin‐like products than those of the Mollisols. Fulvic acids from Alfisols and Mollisols contained mostly aliphatic, O‐substituted alkyl, and carboxylic acid, followed by aromatic groups and small amounts of carbonyl groups. The proportion of nonaromatic and aromatic structures in the fulvic acids of the Alfisols and Mollisols was similar, but slight differences were noted in elemental ratios and 13C NMR spectra. Although only minimal differences were noted among fulvic acids, differences were evident in the chemical and structural properties of humic acids from contiguous Alfisols and Mollisols in southwestern Ohio.
Tillage, Soil Depth, and Precipitation Effects on Wheat Response to Nitrogen
Authors: Rasmussen P. E. , Rohde C. R. 
Published: July 2010

AbstractWheat (Triticum aestivum L.) response to N in semiarid climates is highly influenced by precipitation and tillage, leading to inefficient use of fertilizer and greater potential for groundwater contamination. To improve fertilizer recommendations, we measured white winter wheat response to 45, 90, 135, and 180 kg N ha−1 for 10 crops grown in a wheat‐fallow rotation with three tillage treatments, one conventional (moldboard plow) and two stubble‐mulch (offset disk, subsurface sweep). The soil was a Walla Walla silt loam (coarse‐silty, mixed, mesic Typic Haploxeroll) with three depths to bedrock (208, 132, and 111 cm). Grain yield averaged 5.51, 4.07, and 3.55 Mg ha−1 with above‐ (147), near‐ (88), and below‐normal (61 mm) growing‐season precipitation (GSP). Nitrogen increased yield 3.0, 1.9, and 0.4 Mg ha−1 in these precipitation regimes. Grain yield was not affected by soil depth when GSP was above normal, but 10 to 20% less on the shallower soils when GSP was below normal. There was a trend towards higher yield with conventional tillage when GSP was above normal. The amount of applied N required for optimum yield was >135 kg N ha−1 with above‐normal GSP and <45 kg N ha−1 with below‐normal GSP. Excess N decreased grain yield when GSP was near normal, but not when above or below. Applied N increased straw yield curvilinearly, with little influence of tillage or soil depth. Straw/grain ratio averaged 1.53 and 1.70 on the 208‐ and 111‐cm soils, respectively. Nitrogen uptake tended to be greater in conventional than in stubble‐mulch tillage, and was not affected by soil depth. Grain protein exceeded the desirable level for white wheat only when applied‐N was above that needed for optimum yield. Precise selection of the amount of N to apply each year was difficult because of the strong influence of GSP on yield and the need to apply N before GSP is known.
Land Clearing and Use in the Humid Nigerian Tropics: I. Soil Physical Properties
Authors: Ghuman B. S. , Lal R. , Shearer W. 
Published: July 2010

AbstractSoil physical properties are affected by land clearing use. Long‐range planning in the humid tropics requires monitoring of these effects for an extended period of time. The effects of two land‐clearing methods and six land‐use systems on soil physical properties of an Ultisol were studied for 4 yr in the humid coastal belt of Nigeria. The land‐clearing methods were bulldozer clearing with a shear blade and manual clearing. The six land‐use systems were comprised of cassava (Manihot esculenta Crantz)‐based cropping, oil palm (Elaeis guineensis Jacq.)‐based cropping, alley cropping, plantain (Musa spp.), pasture, and improved forestry, all under no‐tillage. Soil physical properties were measured 90 d after clearing prior to planting, and at 2 and 4 yr after cropping. The soil texture of the 0–10 cm layer was not affected by clearing methods. Soil compaction increased to 30 cm with shear blade and 20 cm with manual clearing. With respect to the forested control, shear blade and manual clearing increased the bulk density in the 0‐ to 10‐cm layer by 22 and 14%, respectively. The bulk density in the surface layer after 2 yr of cropping was significantly more for the pasture than the other systems. Three months after clearing, the steady infiltration rates were 89, 20 and 32 cm h−1 in the forested control, and shear‐blade and manually cleared plots, respectively. Infiltration rate increased to 47 and 51 cm h−1 in the shear‐blade cleared and increased to 290 and then decreased to 156 cm h−1 in the manually cleared plots after 2 and 4 yr of cropping, respectively.
Land Clearing and Use in the Humid Nigerian Tropics: II. Soil Chemical Properties
Authors: Ghuman B. S. , Lal R. 
Published: July 2010

AbstractA 4‐yr study was conducted to investigate the effects of land clearing and subsequent land use on chemical properties of an Ultisol at Okomu, southern Nigeria. After 1 yr of cropping, soil pH, available P, and exchangeable Ca, Mg and K in the topsoil (0–10 cm) were significantly higher in the windrow zones of the shear‐blade‐cleared plots than in the nonwindrow zones, manually cleared plots, or forested control. In manual clearing, the organic‐C and total‐N contents declined below that of the forested control with 3 yr of cropping. Soil pH after 4 yrs and exchangeable K after 2 and 4 yr of cropping were significantly higher in the pasture system than in the other systems. In a given system, pH, organic C, and available P decreased with cropping time. Total N decreased with cropping time in all systems but pasture where there was a little increase. The levels of exchangeable Ca+2 and Mg+2 also decreased with cropping duration in all systems except the alley cropping in which their concentrations increased. The K+ content decreased with time in all systems but the pasture in which its level remained unchanged owing to returning of the hay to the field after cutting.
Uptake of Point‐Injected Nitrogen by Winter Wheat as Influenced by Time of Application
Authors: Janzen H. H. , Roberts T. L. , Lindwall C. W. 
Published: July 2010

AbstractConventional methods of N application to winter wheat often lead to low fertilizer‐use efficiency. Point injection may improve fertilizer efficiency but the optimum time of application has not been established. A field experiment was conducted during two growing seasons at Lethbridge, AB, Canada, on a Typic Haploborall sandy clay loam to determine 15N‐fertilizer uptake as a function of application time and method. The experiment included a factorial of three methods (point‐injected urea‐NH4NO3, broadcast urea, and broadcast NH4NO3,) and four application times (at seeding, late fall, early spring, and late spring) along with two banding treatments (urea and NH4NO3) applied at seeding and a control. For all methods of application, efficiency of fertilizer tended to be highest when applied in early spring. In the point‐injection treatments, average recovery of applied N by wheat was 32% for the seeding, 43% for late fall, 56% for early spring, and 29% for late spring applications. At the optimum time of application, point injection exhibited significantly higher fertilizer recovery than broadcast applications, probably because of direct placement of N into the rooting zone. Fertilizer recovery from banding treatments applied at seeding was lower than from early‐spring point injection, presumably because of overwinter N losses. The results suggest that point injection can significantly enhance fertilizer‐use efficiency and that optimum time of injection is in the early spring just prior to the period of maximum N assimilation by the crop.
Dinitrogen and Nitrous Oxide Flux from Urea Basally Applied to Puddled Rice Soils
Authors: Buresh R. J. , De Datta S. K. , Samson M. I. , Phongpan Sakorn , Snitwongse Patoom , Fagi A. M. , Tejasarwana R. 
Published: July 2010

AbstractNitrification‐denitrification is often regarded as an important N loss process in puddled rice soils, but few direct field measurements of denitrification loss have been reported. Field studies were conducted on a Typic Tropaquept in Thailand, an Aeric Tropaqualf in Indonesia, and an Andaqueptic Haplaquoll in the Philippines to measure (N2 + N2O)‐15N flux, (N2 + N2O)‐15N trapped in soil, and total gaseous 15N loss following basal application of 15N‐labeled urea (87 kg N ha−1) to irrigated rice (Oryza sativa L.) grown on puddled soils. Urea treatments included broadcast applications with and without incorporation to 0.07‐m soil depth. Directly measured (N2 + N2O)‐15N flux during the 10 d following urea application by each method was less than 0.1% of the applied N at the Thailand and Indonesia sites. The (N2 + N2O)‐15N collected from the soil after 10 d did not exceed 0.02% of the applied N. Total gaseous N loss determined from a 15N balance at 10 d after N application without incorporation was 34% of the applied N in Thailand and 31% in Indonesia. Incorporation reduced total N loss to 22% in Thailand and 10% in Indonesia. In the Philippines, the measured (N2 + N2O)‐15N flux during the 15 d immediately following urea application with incorporation was 2.2% of the applied N with chambers placed between rice plants and 3.0% with chambers over the plants. Total N loss at the Philippine site was 40% of the applied N. Ammonia volatilization appeared to be much more important than nitrification‐denitrification as a mechanism of urea‐N loss at the three irrigated lowland study sites.
Chromate Reduction by Subsurface Soils under Acidic Conditions
Authors: Eary L. E. , Rai Dhanpat 
Published: July 2010

AbstractExperimental studies of Cr(VI) reduction by five subsoils (Holston‐Cloudland, Kenoma, Cecil‐Paculet, Watson‐Alvira, and Ocala) were conducted to determine whether the Fe(II) contained in soil minerals could cause Cr(VI) to be reduced to Cr(III) and precipitated as hydroxide solids. All of the subsoils contained small amounts of Fe(II) and organic matter, but only the acidic subsoils (1:2 soil pH = 4.2‐4.3) caused Cr(VI) reduction at their natural pH values. Rates of Cr(VI) reduction by four of the subsoils increased with a decrease in pH below 4.0. Consideration of available kinetic information, coincidental timing of Cr(VI) disappearance and Fe(II) appearance in solution, and observed reaction stoichiometries indicate that Cr(VI) reduction by Fe(II) species is of equivalent importance as reduction by organic material under acidic conditions. Chromium(VI) reduction in the acidic subsoils resulted in the precipitation of (Fe,Cr)(OH)3(am), depending on the solution pH. The amount of NH2OH·HCl‐extractable Fe in the acidic subsoils was found to be useful for determining the mole fraction of Fe(III) in the (Fe,Cr)(OH)3(am) solid solution, allowing prediction of Cr(III) concentrations in acidic solutions to within a logarithmic unit of those observed in experimental soil‐water suspensions.
Sodium‐Calcium Exchange with Anion Exclusion and Weathering Corrections
Authors: Amrhein C. , Suarez D. L. 
Published: July 2010

AbstractIn order to accurately model soil reclamation with concentrated electrolytes such as CaCl2 or sea water, it must be determined if there is an effect of salinity on the Na‐Ca exchange selectivity. A new procedure for determining Na‐Ca selectivity in calcareous and gypsiferous soils was used to study the effects of ionic strength and mineralogy on Na‐Ca exchange. Four specimen clay minerals and three whole soils were equilibrated with solutions ranging in concentration from 10 to 1000 mmolc L−1 and at Na adsorption ratios from 1 to 50 (mmol L−1)1/2. Exchangeable‐cation values were corrected for calcite and gypsum dissolution as well as anion exclusion. The selectivity data were compared with other reported values for Na‐Ca exchange in order to determine if there were any trends in selectivity with mineralogy or surface charge density. Generally, Na‐Ca selectivity was independent of ionic strength. Vermiculite exhibited near‐ideal exchange when compared with the nonpreference isotherm. There was no effect of mineralogy on the Na‐Ca selectivity, even though the soils and minerals had various surface charge densities. The Gapon selectivity coefficients (KG) for the calcareous Many Farms soil (a mesic Torrifluvent) and the gypsiferous Shiprock soil (a mesic Torriorthent) averaged 0.011 and 0.013 (mmol L−1)−1/2, respectively. Failure to correct for anion exclusion and mineral weathering lowered these average KG values to 0.0085 and 0.0064, respectively. The data were compared with the Vanselow (Kv = 4.3), nonpreference (Kv = 1.0), Gapon (KG = 0.015), and the diffuse double‐layer (DDL) models. After the review of the problems associated with the various methods of determining exchangeable cations, we recommend that the alcohol rinse method to remove soluble salts not be used.
Microbial Biomass and Soil Structure Associated with Corn, Grasses, and Legumes
Authors: Drury C. F. , Stone J. A. , Findlay W. I. 
Published: July 2010

AbstractMaintaining long‐term soil productivity requires development of cropping systems that provide maintenance or improvement in soil structure and an understanding of associated rhizosphere microbial populations. The objectives of this study were to determine the effects of several crops on soil biomass C and biomass N contents, their within‐season variability, and the relationships between changes in soil biomass C, biomass N, and soil structure on a Brookston clay loam soil (fine‐loamy, mixed, mesic Typic Argiaquoll). Soil microbial biomass C, biomass N, and soil‐structure parameters (wet aggregate stability [WAS], organic carbon [OC], dry aggregate mean weight diameter [MWD], bulk density, and total and air‐filled porosity) were measured during the third year of corn (Zea mays L.), soybean (Glycine max [L.], Merr.) alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), reed canarygrass (Phalaris arundinacea L.), orchardgrass (Dactylis glomerata L.), and no‐crop (bare, covered, and shaded) plots at monthly intervals (June, July, August, and September). Reed canarygrass resulted in greater biomass‐C contents than both the corn and soybean at all four sampling dates. Soil biomass C under alfalfa was significantly greater than under corn and soybean for both the first and last sampling dates. Forage species did not affect the soil biomass‐N content. No consistent effects of the no‐crop treatment on biomass C or biomass N were observed between sampling dates. Biomass C was significantly correlated with WAS, OC, and MWD for the cropping treatments. Wet aggregate stability was negatively correlated with soil water content for both the no‐crop and cropping treatments, indicating that improvements in structure were not solely the result of the cropping treatments and associated rhizosphere populations. Reed canarygrass resulted in greater soil biomass C/N than the alfalfa, corn, and orchard grass plots, suggesting that fungal activity, and therefore soil structure, may be preferentially enhanced in the presence of reed canarygrass. This study demonstrated the influence of forage species and seasonal variability on concurrent changes in microbial biomass and soil structural properties.
Loblolly Pine Seedling Response to Fertilizer and Lime Treatments on a Spodosol
Authors: Coultas C. L. , Hsieh Y. P. , McKee W. H. 
Published: July 2010

AbstractLoblolly pine trees (Pinus taeda L.) grow poorly on the Spodosols of the mid‐Atlantic Coastal Plain. This greenhouse study was undertaken to determine the effects of N, P, S, micronutrients, and lime on the growth of Loblolly pine seedlings in the Al horizon of a Lynn Haven fine sand (sandy, siliceous, thermic Typic Haplaquod). Nitrogen, and N‐P in combination resulted in increased growth of the pine seedlings. A small application of CaCO3 (2337 kg/ha) resulted in reduced growth and increased foliage necrosis. This negative effect was overcome by N applications. Micronutrients alone had little effect on growth and the foliage concentrations were adequate with all treatments. Sulfur treatment had a slight effect on plant growth but, with S, foliage N was increased from 17.5 to 19.0 g/kg. Aluminum concentrations were determined to be at nontoxic levels in this soil horizon. We postulate that the negative effect of CaCO3 on plant growth was due to reduction of available N. The mechanism for this result has yet to be elucidated.
Soil Permeability in an Ammonium and Phosphorus Application Zone
Authors: Myers R. , Thien S. J. 
Published: July 2010

AbstractSoil organic matter plays a primary role in the development and maintenance of aggregate stability necessary for good soil permeability. Studies showing that some N and P fertilizers dissolve soil organic matter raise questions about effects these fertilizers have on permeability. In this work, filtration rates (FR) in Kennebec silt loam (fine‐silty, mixed, mesic Cumulic Hapludoll) were monitored after addition of NH4OH and NH4 phosphates to determine whether organic‐matter dissolution occurring after fertilizer application affected soil permeability. Twenty combinations of NH4OH and either monoammonium phosphate (MAP) or triammonium pyrophosphate (TPP) were applied to soil columns 70 mm in diameter. The columns were incubated for 0.5, 1, 2, 4, 8, 16, or 32 d at 35 °C. Soil from the application zone was removed from the column and analyzed. Increasing NH4OH levels usually decreased FR. Compared with FR when no NH4OH was applied, NH4OH levels of 1500, 3000, and 6000 mg kg−1 reduced FR 20, 30, and 33%, respectively. Treatments including P had variable effects on permeability. With the following P sources and levels (mg P kg−1): 0 P, 300 MAP‐P, 300 TPP‐P, 600 MAP‐P, and 600 TPP‐P, average FR (1 + log mL min−1) were 2.13, 1.99, 1.88, 2.25, and 1.72, respectively. The NH4OH and P treatments dissolved between 0.1 and 4.8% of the total organic matter in the analyzed samples. Increases in dissolved organic matter were highly correlated with decreases in FR (R2 = 0.78‐0.98). Increased dissolution of organic matter increased soil dispersion and lowered permeability in the application zone.