bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature and Water Profiles During Diurnal Soil Freezing and Thawing: Field Measurements and Simulation
Authors: Pikul J. L. , Boersma L. , Rickman R. W. 
Published: July 2010

AbstractAgricultural soils of the inland Pacific Northwest undergo frequent freezing and thawing during the winter and early spring. Repeated freezing and thawing of the soil surface may accelerate breakdown of soil aggregates, resulting in decreased water infiltration, and erosion resistance. The objective of this research was to simulate soil temperature and water distributions in a field soil during freezing and thawing. A finite difference numerical model was used to simulate soil temperature, depth of freezing, and water movement. Field measurements of soil temperature, ice and water content, and freezing depth in a bare surface treatment were used to validate the simulation model. The model couples heat and water flow equations by the change in soil ice content. An experimental relationship between unfrozen water content and degrees below freezing was used to estimate the change in soil ice content. Soil heat and water flux during 7 h of freezing followed by 12 h of thawing were simulated for two different days when the soil froze to a depth of 1.5 cm, Test 1, and 0.75 cm, Test 2. Simulated maximum frost depths were 1.4 and 0.8 cm for the respective tests. Simulated ice and water content of the 0‐ to 1‐cm soil layer, at the time of maximum forst penetration was 0.46 and 0.41 cm3/cm3, which compares to measured values of 0.49 and 0.49 cm3/cm3 for the respective tests. Correlation of measured soil temperature and simulated soil temperature at the 1‐cm depth was 0.99 for both tests. Standard deviation of the differences between measured and simulated temperature at the 1‐cm depth was 1.04 and 0.29 °C for the respective tests. These results support the validity of this modeling approach for diurnal simulations of heat and water flux, near the surface, in freezing and thawing soil.
Sunflower Growth and Nutrient Uptake: Response to Tillage System, Hybrid Maturity and Weed Control Method
Authors: Deibert Edward J. , Utter Rodney A. 
Published: July 2010

AbstractLimited information is available on the influence of reduced tillage systems, weed control methods and hybrid maturity on growth and nutrient uptake of sunflower (Helianthus annus). A study was conducted during 1985 to 1986 on a Fargo clay (fine, frigid, montmorillonitic Vertic Haplaquoll) to evaluate plant growth, drymatter production, and N, P, and K content at vegetative stage (V‐16), reproductive stage (R‐5), and seed at harvest of early and late maturity hybrids as influenced by conventional tillage (fall plow) or reduced tillage (fall sweep, fall intertill, and no‐till) and weed control by herbicides or herbicides plus cultivation. Plant height and dry‐matter at V‐16 were higher with reduced tillage in 1985 with limited precipitation, but lower than conventional tillage in 1986 with above normal precipitation. Hybrids performed similarly at V‐16, but by R‐5, height and drymatter were greater for the late hybrid. No‐till and intertill systems produced more drymatter than plow at R‐5. Maximum seed drymatter was produced with intertill and no‐till in 1985, but in 1986 the plow system gave the highest seed production. Nutrient content in sunflower plants and seeds was similar between hybrids, weed control methods, and years. Nutrients in sunflower plants and seeds were similar among tillage systems even though lower nitrate‐N and stratification of P and K in the soil was measured with reduced tillage. Results indicate that reduced tillage sunflower production with adequate weed control is similar to conventional plow systems and that early maturing hybrids produced yields comparable to late hybrids under these tillage and climatic conditions.
Chemical Properties of Native Savanna and Forest Soils in Central Brazil
Authors: Cochrane Thomas T. 
Published: July 2010

AbstractRecent research of the well‐drained cerrados (savanna) soils of Brazil suggests that poor root growth associated with inferior crop production is often caused by subsoil Ca deficiency rather than Al toxicity. The present study was conducted to re‐examine this hypothesis and to compare native soil vegetation patterns. Horizon samples from 48 representative soils of the Geo‐Economic region of Brasilia, an area covering 22‐million hectares of central Brazil, were analyzed for NH4NO3 exchangeable cations, and cation and anion exchange capacity. Thirty eight of these soils were found under cerrados and 10 under the minor inclusions of native forests scattered throughout the predominantly savanna landscape. Calcium deficient soil conditions were only found in cerrados, although cerrados also occurred on high Ca soils. The Ca/Mg ratios were significantly higher in the forest vs. cerrados soils. Low Ca/K ratios and high anion exchange capacity/cation exchange capacity AEC/CEC ratios were common in cerrados soils. The Mg/K ratios were satisfactory in most of the soils. It is concluded that the Ca/Mg ratios of the cerrados soils should be examined in an agricultural context.
Silicification of Holocene Soils in Northern Monitor Valley, Nevada
Authors: Chadwick O. A. , Hendricks D. M. , Nettleton W. D. 
Published: July 2010

AbstractIn Monitor Valley, Nevada, two Entisols and an Aridisol containing volcanic glass have silica cementation that is first manifest as microagglomerates and later as macroscopic (>2‐mm) durinodes and weakly cemented s‐matrix. The initial effect of silicification is cementation of silt and clay by opaline SiO2, producing silt‐ and sand‐size microagglomerates that are one source of large −1.5 MPa H2O/clay values for the <2‐mm soil fraction. In the illuvial zone, microagglomerates are nuclei for further silica cementation and eventual durinode formation. Volcanic glass is a major source of silica for cementation; the 0.05‐ to 0.10‐mm sand fraction is commonly composed of >40% volcanic glass, of which 40 to 80% is partly weathered; greatest proportions of weathered glass occur at about the same depths as maximum pH. Laboratory measurements of water‐soluble silica and 0.5 M NaOH extractable silica, as well as the −1.5 MPa H2O/clay ratio, provide indications of incipient silicification. These values are relatively large throughout the sola but reach maxima before decreasing with increasing depth. This pattern indicates that glass weathering and relatively short‐distance silica illuviation influence these recent soils.
The Effect of Two Polymers and Water Qualities on Dry Cohesive Strength of Three Soils
Authors: Aly Saleh M. , Letey J. 
Published: July 2010

AbstractThe effects of two polymers, cationic guar (CP‐14) and anionic polyacrylamide (PAM), and two water qualities on dry cohesive strength of three soils were studied. The soils were Fallbrook sandy loam (fine‐loamy, mixed, thermic, Typic Haploxeralf), Bosanko sandy clay loam (fine, montmorillonitic, thermic, Chromic Pelloxererts), and Hanford loamy sand (coarse‐loamy, mixed, nonacid, thermic, Typic Xerorthents). The two polymers were applied with synthesized Friant‐Kern Canal or well water typical of the San Joaquin Valley of California (EC 0.05 and 0.7 dS m−1, respectively). The soil was used either directly (nonpretreated) or pretreated by spraying the waters containing polymers to create concentrations of 0, 25, 50 and 100 mg polymer per kg soil and then air‐drying the soil. Soil briquets and soil cores of pretreated soil were saturated with untreated water and nonpretreated soil was saturated with waters containing polymer concentrations of 0, 5, 25, 50 and 100 mg L−1. The saturated soil was drained, dried at 60 °C for 48 h and then the dry cohesive strength was measured by modulus of rupture (MR) of soil briquets and tensile strength (S) of soil cores. The rupture stress (RS) required for crushing three group sizes (2–4, 4–5.66 and 5.66–8 mm) of artificially prepared soil aggregates using the various solutions was also measured. Both polymers were effective in ameliorating soil hardness, but PAM was more effective than CP‐14 in either water. The degree to which MR, S and R decreased with polymer applications was dependent upon the soil type, water quality, polymer concentration and method of polymer application. Pretreated Bosanko soil showed higher MR values in canal water than in well water for both polymers. Fallbrook soil showed the same trend as Bosanko soil with CP‐14 and opposite results with PAM. Higher values of MR were obtained in nonpretreated soil than in pretreated soil for Bosanko soil in both canal and well water. In general, differences in MR between pretreated and nonpretreated Fallbrook soil were not great. Reasonable agreement was found between measured MR and RS of the three soils and predicted results based on flocculation and polymer adsorption on montmorillonite.
Aluminum Leaching by Mineral Acids in Forest Soils: I. Nitric‐Sulfuric Acid Differences
Authors: James Bruce R. , Riha Susan J. 
Published: July 2010

AbstractIn laboratory studies simulating snowmelt leaching of forest soils, HNO3 leached more Al than did H2SO4 from soil columns containing a forest floor‐spodic horizon sequence (FF/Bs) representative of high elevation forest soils and watersheds thought to be sensitive to acidification by acid precipitation. Increasing the HNO3 concentration 100‐fold (pH 5 to 3) increased total Al concentration in leachates from 0.70 to 0.85 mM, while increasing H2SO4 concentration had no effect. Addition of pH 3 H2SO4 to the FF/Bs columns raised leachate pH relative to pH 3 HNO3 and control treatments, and resulted in the lowest Al concentrations of all treatments in the first three of four sequential leachings. In albic (E) and ochric (A) mineral soil horizons below a forest floor, there were no differences between the acids and no effects of changing acid concentration. Concentrations of Al leached by the acids did not differ from those in control treatments. The differences in effects of HNO3 and H2SO4 on soluble Al and pH in the Bs horizon and the lack of effect of either acid in the E and A horizons imply that the type of mineral horizon below the forest floor and the kind of acid leaching through these horizons are pertinent to predicting lake acidification in diverse forested watersheds. The results also have implications for pollution control strategies focusing solely on SO2 emissions and designed to mitigate lake acidification.
Aluminum Effects on Northern Red Oak Seedling Growth in Six Forest Soil Horizons
Authors: Joslin J. D. , Wolfe M. H. 
Published: July 2010

AbstractThe response of northern red oak (Quercus rubra L.) seedlings to varying levels of soil Al was examined in a 16‐wk greenhouse study. Forest soil samples representing three soil series were used as growth media: Captina (Fragiudult, Missouri), Lexington (Paleudalf, Mississippi) and Becket (Fragiorthod, New York). Soil from two horizons from each series was separately amended in four treatments to create a wide range of soil Al availability: (i) control, (ii) limed [Ca(OH)2], (iii) acidified (HCl), (iv) acidified with supplemental calcium added (+ HCl and CaSO4). Treatments significantly (p < 0.05) altered soil pH (range 3.65 to 5.48), base saturation, and 0.01 M SrCl2‐extractable Al (range 0.6–37.2 mg kg−1). Compared to controls, both acidification treatments resulted in significant reductions in fine root and foliar biomass production or in fine root branching, in all horizons except the highly organic Bhs of the Fragiorthod. In the remaining five horizons, fine root branching and biomass production were highly and negatively correlated (R2 = 0.70 and 0.50, respectively) with 0.01 M SrCl2‐extractable Al. Although fine root tissue concentrations of Al correlated highly with 0.01 M SrCl2‐extractable Al levels, root tissue Al predicted root branching and biomass only moderately well (R2 = 0.30 and 0.21, respectively). Fine root branching was more sensitive to treatment effects than either root biomass production or root elongation. Reductions in foliar biomass appeared to be secondary responses to direct effects on root systems. Present soil Al levels and acidic deposition rates appear to pose no threat to northern red oak in the southern portion of its range, whereas the possibility of Al toxicity in northeastern Spodosols deserves further study.
Sulfur Speciation in Some Chesapeake Bay Tidal Marsh Soils
Authors: Haering K. C. , Rabenhorst M. C. , Fanning D. S. 
Published: July 2010

AbstractIn order to study S compounds and processes in Chesapeake Bay marshes, Sulfihemist profiles were sampled along a transect from inland to streamside marsh areas of Cedar Creek Marsh and in seven marshes along the Nanticoke River in Dorchester County, MD. In both areas, higher concentrations of pyrite were found in areas that received Fe inputs from tidal overwash or from diffusion from mineral layers within the profile. Pyrite accumulation was favored in streamside profiles that were subjected to frequent tidal flushing. Pyrite was the major form of S in most of the organic horizons of the Cedar Creek streamside pedons and in several of the Nanticoke pedons. Organic S was the major form of S in the Cedar Creek inland pedons. In both study areas, organic C was correlated with total S, apparently because of the S associated with organic materials and the ability of organic matter to hold sulfate‐containing tidal water. High total S values were found to be indicators of areas of organic S accumulation. Pyrite content was not significantly correlated with total S or organic C. Identification of “sulfidic materials” for purposes of soil classification should be based on analysis of pyrite S, as total S may be a poor estimate of oxidizable sulfides.
Canopy Shading Effects on Soil Heat and Water Flow
Authors: Horton Robert 
Published: July 2010

AbstractA method to model two‐dimensional heat and water flow in soil as influenced by shading from a row crop is developed. The numerical method predicts the surface energy partitioning, soil temperature, and the water content as influenced by soil surface evaporation in the absence of water uptake by roots. Standard weather information, canopy shape factors, and soil thermal and hydraulic properties are the inputs required to make predictions. Although the present model does not include water uptake by roots, this feature can be added. The methods of prediction are compared with analytical methods in verification and benchmarking test problems. Predictions of soil surface temperature and subsurface temperature in a verification test scenario closely agree with analytical solution values. Predicted soil water contents during an infiltration event agree closely with analytical values predicted by a quasi‐analytic simulator (used in a benchmarking test), and also with experimental data (used in a validation test). A 10‐d simulation is performed to show the ability of the method to describe surface energy partitioning and soil profile conditions. The method is shown to provide reasonable results. For the specific scenario of this simulation, the diurnal time variation of surface energy partitioning, soil water content, and soil temperature exhibited a radical change when the soil located between plant rows dried to residual water content. Large spatial variations in soil energy fluxes, temperature, and water content are predicted when soil located between plant rows becomes drier than soil below the canopy. The method can predict these fluxes, which are very difficult to obtain by direct measurement. Thus, this method should have a wide range of applications in soil and crop sciences.
Bivalent Ion Adsorption by an Oxisol
Authors: Charlet Laurent , Sposito Garrison 
Published: July 2010

AbstractSurface excesses of the bivalent ions Ca2+, Mg2+, and SO2‐4 were measured on a Brazilian Oxisol suspended in Ca(ClO4)2), Mg(ClO4)2, or Li2SO4 solution. The surface excess of Ca2+ increased proportionally with pH in the range 2.5 to 6.0 and was independent of ionic strength in the range 26 to 67 mol m−3. The surface excess of Mg2+ as a function of pH, however, showed a significant dependence on ionic strength in the range from 34 to 176 mol m−3. The surface excess of SO2‐4 showed a dependence on ionic strength in the range 12 to 37 mol m−3 if pH was less than the point of zero net charge (PZNC = 4.2), but showed no dependence on ionic strength if pH was above the PZNC. All three bivalent ions showed significant adsorption above the PZNC of the soil. These trends were interpreted conceptually to suggest that, although the three bivalent ions may form both outer‐sphere and inner‐sphere surface complexes, the latter are more important for Ca2+ than for Mg2+ or SO2‐4.
Spatial Variability of Soil Chemical Properties in Grazed Pastures
Authors: West C. P. , Mallarino A. P. , Wedin W. F. , Marx D. B. 
Published: July 2010

AbstractExcretal deposition concentrates nutrients in animal watering and resting areas of pastures, and including these areas in soil sampling may bias fertilizer recommendations. Our objective was to determine the magnitude and extent of nutrient enhancement near a water source in each of two experimental tall fescue (Festuca arundinacea Schreb.) pastures. The rectangular 0.44‐ha pastures were in southcentral Iowa and included three soils: a fine, montmorillonitic, mesic Typic Argiaquoll, a fine‐loamy, mixed, mesic Typic Argiudoll, and a fine, montmorillonitic, mesic Aquic Argiudoll; pH 6.8 to 7.0. Before grazing began in 1976, extractable P (Bray and Kurtz P‐1) and exchangeable K ranged from 3 to 9 and 87 to 156 mg kg−1, respectively, at 0 to 75 mm. After 5 yr of grazing by cattle, soil was sampled at 0 to 75 and 75 to 150 mm on a grid pattern starting at the water source and analyzed for extractable P and exchangeable K, total N, and organic C. Chemical values between the grid points were interpolated by kriging, and contour plots were constructed for each variable. Extractable P and exchangeable K exhibited large accumulations near the water source, with many P and K measurements exceeding 100 and 1000 mg kg−1, respectively. The zone of enhanced P and K levels extended to approximately 10 to 20 m from the water source. Total N declined from 4.2 to 2.1 g kg−1 with progressive distances from the water; however, the range of values was proportionately less than for P and K. Organic C concentrations showed less distinct trends in relation to distance from the water source. The results showed a distinct zone of nutrient enhancement within 20 m of the water source that should be either avoided or sampled separately when sampling pastures for fertilizer recommendations.
Calcium and Magnesium Availability and Uptake by Rice in Acid Sulfate Soils
Authors: Moore P. A. , Patrick W. H. 
Published: July 2010

AbstractDeficiencies of Ca and Mg have been suggested to be constraints on rice (Oryza sativa L.) growth in acid sulfate soils. This study was conducted to determine the solubility of Ca and Mg under natural conditions in these soils, to determine what governs the solubilities of these metals, and to investigate uptake of these metals by rice. Metal availability and uptake by rice were evaluated in 134 flooded acid sulfate soils in the Central Plains region of Thailand and in a growth chamber study utilizing 50 of the same soils. Metal activities in soil solutions were determined using GEOCHEM. The results of this study indicate that the soils studied were generally undersaturated with respect to Ca and Mg minerals, suggesting that mineral equilibria probably does not govern the solubility of these metals in acid sulfate soils. Exchange isotherms indicated that Ca2+ and Mg2+ in soil solutions were in equilibrium with Ca and Mg on the cation exchange capacity. Therefore, cation exchange reactions probably govern the solubility of Ca2+ and Mg2+ in acid sulfate soils. The results also showed that although Ca and Mg uptake by rice is correlated with Ca2+ and Mg2+ activity, a more pronounced relationship exists between uptake and the divalent charge fraction in soil solution attributable to these cations. This was believed to be due to competitive inhibition for uptake sites. This study also demonstrated that Ca and Mg deficiencies in rice may be occurring on these soils.
Processes and Rates of Pedogenesis in Some Maryland Tidal Marsh Soils
Authors: Griffin T. M. , Rabenhorst M. C. 
Published: July 2010

AbstractTidal marsh profiles from various locations around the Chesapeake Bay were dated using 210Pb geochronology. These soils, which were classified as Typic and Terric Sulfihemists, Typic and Histic Sulfaquents, and Histic Hydraquents, were characterized with respect to bulk density, organic matter content, S and Fe speciation, and pyrite content. These characteristics were interpreted in the context of marsh accretionary activity and soil forming processes. Rates of vertical accretion ranged between 0.35 and 0.75 cm yr−1, indicating that the marshes examined are keeping pace with published rates of sea level rise. Generally, those marshes accreting most rapidly contained a higher mineral content and a higher reactive Fe (FeS2‐Fe plus “free” Fe) content. Pyrite S and organic S were the dominant S species forming from the microbial reduction of SO2‐4. Redox conditions, Fe reactivity, organic matter content, and SO2‐4 concentrations were the major factors controlling S and Fe transformations. Models developed to define different marsh environments with respect to pyrite formation and the degree of pyritization illustrate that in those marshes receiving low rates of mineral sediments (i.e., slowly accreting marshes), the amount of reactive Fe is limiting FeS2 formation, the FeS2 content is low, degree of pyritization (Py) is high, and the dominant S species is organic S. Where the reactive Fe content is high (i.e., rapidly accreting marshes) and SO2‐4 reduction is not retarded, the FeS2 content is high and Py is moderate to high. If reactive Fe is high and SO2‐4 reduction is impeded for some reason, then FeS2 formation becomes limited by the SO2‐4 reduction rate, and the FeS2 content and Py will be variable.
Erosion Effects on Productivity of Cecil Soils in the Virginia Piedmont
Authors: Thomas P. J. , Simpson T. W. , Baker J. C. 
Published: July 2010

AbstractA study was initiated in two counties in the southern Virginia Piedmont to assess the effects of erosion on soil properties and crop productivity. Plots were established in farmer‐cooperator fields on slightly, moderately, and severely eroded Cecil soils (clayey, kaolinitic, thermic Typic Kanhapludults). The Ap horizon decreased as severity of erosion increased, although no differences were observed for Bt and solum thicknesses. Clay content of the Ap horizon increased as the severity of erosion increased. Increases in clay content were reflected by several soil properties. The volumetric water contents at −10 kPa and −1500 kPa increased with clay content of the Ap horizon, but the differences in plant available water remained at 0.09 m3 m−3. Thus, the effect of erosion on plant available water in both the Ap and Bt horizons was negligible. Cation exchange capacity was higher on the severely eroded sites. Exchangeable Al, expressed as either percent of the exchange complex or as concentration in the soil, was lower than expected and had no apparent adverse effect on yields. Available P decreased with severity of erosion and was significantly correlated with soybean [Glycine max (L.) Merr.] grain yield. Grain yields were greater on the slightly and moderately eroded sites compared to the severely eroded sites. This was attributed to levels of available P in the slightly and moderately eroded soils that were above the 18 mg kg−1 critical P level for optimal crop growth, while available P was below 18 mg kg−1 in the severely eroded soils. The magnitude of difference between noneroded and eroded soils may be difficult to assess because of the scarcity of uneroded upland Piedmont soils by which such comparisons are made. Thus, estimates of the impact of the severity of erosion in the Piedmont may be difficult to establish.