bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Transformations in Surface‐Applied Poultry Litter: Effect of Litter Physical Characteristics
Authors: Cabrera M. L. , Chiang S. C. , Merka W. C. , Thompson S. A. , Pancorbo O. C. 
Published: July 2010

AbstractPassing poultry litter through a fine sieve (<0.83 mm) generates a fine fraction that is higher in N concentration than the whole litter and cheaper to transport per unit of N. This fine fraction can be pelletized to facilitate handling, but changing the physical characteristics of the litter may change the amount of N loss or the rate at which N mineralizes. The objective of this work was to evaluate the effect of physical characteristics of the fine poultry litter fraction (pelletized or fine particles) on net N and C mineralization, NH3 volatilization, and denitrification resulting from surface applications of the fine fraction to Cecil loamy sand (clayey, kaolinitic, thermic Typic Kanhapludult) and Dothan loamy sand (fine‐loamy, siliceous, thermic Plinthic Kandiudulf) soils. The soils were adjusted to 52% water‐filled porosity, treated with either pelletized or fine‐particle poultry litter at 30.7 g N m−2, and incubated at 25 °C for 35 d. Humidified air was circulated over each sample (15 chamber volumes min−1) and the NH3 evolved was trapped in 0.025 M H2SO4. Inorganic N contents and rates of denitrification and respiration were measured at 1, 3, 7, 14, 21, and 35 d after application. The physical characteristics of the litter did not affect total amounts of net N mineralized and NH3 volatilized in 35 d. However, total denitrification losses were significantly higher for pelletized (6.2% of the applied N in Dothan and 7.9% in Cecil) than for fine‐particle litter (0.2% in Dothan and 0.8% in Cecil). Thus, surface application of pelletized litter may result in increased denitrification losses compared with fine‐particle litter.
Potassium and Phosphorus Uptake by Competing Pine and Grass: Observations and Model Verification
Authors: Smethurst P. J. , Comerford N. B. 
Published: July 2010

AbstractA computer model (COMP8) was recently presented that simulates nutrient uptake by competing and single root systems. However, the model needed independent verification. Our objectives here were to: (i) determine if uptake by each species was a simple function of each species' root surface area, and (ii) verify COMP8 for K and P uptake by slash pine (Pinus elliottii Engelm. var. elliottii) seedlings in competition with Panicum aciculare Desv. ex Poir. in Lam. grass plants. Pine and grass plants were grown together at low and high initial soil‐solution concentrations. Observed and predicted uptake values were compared by linear regression and by t tests using variances predicted by Monte Carlo analysis. For high initial solution conditions, we quantitatively predicted pine uptake for all cases of P and for three of four cases for K. Grass K uptake was accurately predicted in all three cases; however, none of the three cases of grass uptake of P were correct. For the low initial solution concentrations, only one case of pine and no cases of grass uptake were predicted accurately. For neither K nor P was uptake by pine (expressed as a percentage of that taken up by pine and grass combined) in a 1:1 relationship with the percentage of surface area in pine roots. We conclude that uptake by the competing root systems is not a simple function of their relative root surface areas and that COMP8 provides an adequate description of nutrient uptake by competing and contrasting root systems under certain, well‐defined conditions.
A Perspective on Diffuse Natural Recharge Mechanisms in Areas of Low Precipitation
Authors: Stephens Daniel B. 
Published: July 2010

AbstractExtensive studies document that significant recharge can occur in arid and semiarid climates, even where annual potential evapotranspiration exceeds precipitation. This overview focuses on the importance of considering diffuse recharge mechanisms. The recharge mechanisms discussed include infiltration, redistribution, and evapotranspiration, particularly as they are influenced by climate, spatial heterogeneity, anisotropy, preferential flow, and multidimensional flow. Diffuse recharge, calculated for sites having substantially different geography and soil types, only varies by roughly four orders of magnitude. Temporal variability in recharge is attributed primarily to variability in precipitation patterns, evapotranspiration demands, runoff characteristics, and soil hydraulic properties. Examples of field studies of diffuse recharge emphasize sites in New Mexico.
Positional and Temporal Changes in Ponded Infiltration in a Corn Field
Authors: Prieksat M. A. , Kaspar T. C. , Ankeny M. D. 
Published: July 2010

AbstractInfiltrating rainwater can move agricultural chemicals through soil and may contribute to contamination of drinking water supplies. Ponded infiltration rates were measured in corn (Zea mays L.) fields at four positions relative to plants and to crop rows: center of a trafficked interrow (TRK), center of an untrafficked interrow (UNT), between corn plants in a row (BPIR), and directly over the base of a plant in a row (OPIR). Measurements were taken in chisel‐plow plots during 1990 and 1991, and in no‐till plots during 1991. A Canisteo silty clay loam (fine‐loamy, mixed [calcareous], mesic Typic Haplaquoll) was the predominant soil type in the plots. In chisel‐plow plots, infiltration rates for TRK and UNT positions remained relatively constant during both years, with temporary increases after tillage or cultivation. At BPIR and OPIR positions, infiltration rates increased steadily over the growing season. Infiltration rates at the OPIR position increased from 43 to 211 µm s−1 in 1990 and from 63 to 257 µm s−1 in 1991. At the end of both growing seasons, the OPIR position had the greatest infiltration rate, and the TRK position the lowest. In no‐till, infiltration rates at all positions remained relatively constant throughout the 1991 growing season. Infiltration rates at BPIR and OPIR positions were not different from each other, were greater than 200 µm s−1, and were higher than rates at TRK and UNT positions. High potential infiltration rates in the row, especially around the bases of corn plants, have implications for the management of row‐banded chemicals.
Seal Formation and Interrill Soil Erosion
Authors: Levy G. J. , Levin J. , Shainberg I. 
Published: July 2010

AbstractInterrill soil erosion depends primarily on soil detachment by raindrop impact (splash) and the transport capacity of thin sheet flow. Both splash and sheet flow erosion depend on soil surface properties. The purpose of this study was to investigate the effect of seal formation on interrill soil loss. Samples of three soil types — a Typic Chromoxerert, a Calcic Haploxeralf and a Typic Rhodoxeralf — with various naturally occurring exchangeable sodium percentage (ESP) levels were used. The soils were exposed to simulated rain using three different waters: distilled (DW), tap (TW), and saline (SW). The electrical conductivity (EC) of the TW and SW was 0.8 and 5.0 dS m−1, respectively. Seal formation was characterized by the final infiltration rate (FIR) and amount of runoff. Seal formation was enhanced with an increase in soil sodicity and a decrease in water salinity for each soil type. Nearly 70% of the variation in FIR (and seal formation) was explained by water salinity and soil ESP. Most of the variation in soil loss was explained by clay content, soil ESP, and water salinity. With the exception of samples with ESP <5 rained on with DW, soil loss increased linearly with an increase in soil clay content. Seal strength, as inferred from surface pitting by impacting raindrops, decreased with an increase in clay content, and was inversely related to soil erosion.
Soil Microbial Biomass Dynamics and Net Nitrogen Mineralization in Northern Hardwood Ecosystems
Authors: Holmes William E. , Zak Donald R. 
Published: July 2010

AbstractSoil temperature, water potential, and substrate (C) availability are the primary constraints on microbial activity within soil and display substantial seasonal variation within northern deciduous forests. Following autumn litterfall, soil C availability is relatively high, and N should be assimilated by soil microorganisms to maintain or form new biomass. Conversely, N should be mineralized from microbial biomass during midsummer when C availability is relatively low and soil temperatures are high. Because N availability is directly controlled by microbial activity, we hypothesized that microbial biomass and net N mineralization are inversely related on a seasonal basis. To test this hypothesis, we studied the temporal relationship between microbial biomass (C and N) and rates of net N mineralization in two different northern hardwood ecosystems, one dominated by sugar maple (Acer saccharum Marsh.) and basswood (Tilia americana L.) and the other by sugar maple and red oak (Quercus rubra L.). In situ buried bags were used to estimate net N mineralization and nitrification at monthly intervals for 1 yr. Microbial C and N contents of the incubated soil were determined using the chloroform fumigation‐incubation method. Net N mineralization displayed marked seasonal variability, ranging from 35 to 115 mg N m−2 d−1 during the growing season. In contrast, microbial biomass C and N were relatively constant throughout the year, averaging 112 g C m−2 and 17 g N m−2. Neither microbial biomass (C or N) nor the change in microbial biomass between sampling dates were significantly inversely correlated with mean daily rates of net N mineralization. As such, our data do not support the idea that N availability is controlled by large seasonal fluctuations in soil microbial biomass. Rather, our results suggest that N availability is primarily controlled by changes in the turnover rate of microbial biomass such that a relatively constant pool is maintained through time. In addition, mean annual rates of net N mineralization and nitrification did not differ significantly from those previously measured by others in the same stands, suggesting that annual rates may be relatively consistent in climatically similar years.
Volatilization of a Multicomponent Liquid through Dry Soils: Testing a Model
Authors: Nye P. H. , Yaron B. , Galin Ts. , Gerstl Z. 
Published: July 2010

AbstractSpilled or leaked petroleum products often contaminate groundwater and subsequently evaporate through the soil to the atmosphere by gaseous diffusion. This study developed and tested a model that can predict the rate of diffusion through a dry soil column of the individual components in a liquid mixture when they are of low or intermediate volatility. We derived equations that relate the vapor pressures of the components to their sorption from the gaseous phase by the soil. We also provided for slow sorption. Three cases of increasing complexity were treated: evaporation of a mixture directly into the atmosphere; evaporation of a mixture through a soil column without significant sorption; and finally, evaporation through a highly sorting soil column, for which a computer program was written. The model has been tested by comparing the evaporation of m‐xylene and n‐dodecane mixtures through sand, and air‐ and oven‐dry Evesham clay soil (Aquic Eutrochrept or orthic grumaquert) in the laboratory. The equilibrium sorption isotherms and sorption kinetics for these soils and compounds were determined in separate experiments, and other parameters were obtained from the literature, so that the model contained no adjustable fitting parameters. There was fair agreement between the model predictions and the experimental results. Discrepancies were attributed to errors in chemical analysis and the boundary effects that arose from rather short columns, and to the assumptions that the compounds did not compete for sorption sites on the soil, that Raoult's Law was obeyed, and that there was no hysteresis in the sorption isotherms.
Sorption and Redox Transformation of Arsenite and Arsenate in Two Flooded Soils
Authors: McGeehan S. L. , Naylor D. V. 
Published: July 2010

AbstractThe fate of As in soils is regulated mostly by its participation is sorption reactions and redox transformations. Few studies have examined the rate of arsenite and arsenate reduction or the extent to which these redox transformations may be affected by sorption reactions. The objective of this study was to examine changes in solution concentrations of H3AsO03 and H2AsO−4 in two soils subjected to prolonged flooding. The soils, which differed in H3AsO03 and H2AsO−4 sorption capacities, were flooded by suspending 1 g of soil in 25 mL of a solution containing 0.01 M CaCl2 and 1 g d‐glucose kg−1. The suspensions were amended with NaAsO2 or Na2HAsO4·7H2O and were incubated for 0.5 h to 20 d. Changes in solution chemistry (electrode potential [Eh], pH, and dissolved Fe, Mn, H3AsO03, and H2AsO−4) were observed with time. Sorption processes controlled the dissolved concentrations of H3AsO03 and H2AsO−4 during initial stages of flooding. When anaerobic conditions were achieved, dissolution of Fe and Mn oxyhydroxides occurred, causing desorption of H3AsO03 and H2AsO−4. In NaAsO2‐amended suspensions, desorbed H3AsO03 disappeared from solution within 10 d. In Na2HaSO−4‐amended suspensions, desorbed H2AsO−4 also disappeared within 10 d. Concurrent with the disappearance of H2AsO−4 was the appearance of H3AsO03, indicating that H2AsO−4 was rapidly reduced to H3AsO03. First‐order plots of H3AsO03 and H2AsO−4 disappearance had a linear relationship. Rates of desorption and disappearance of H3AsO03 and H2AsO−4 were slower in the soil with higher adsorption capacity, suggesting that sorption processes may influence redox transformations of As oxyanions.
Adsorption of Aniline on Layer Silicate Clays and an Organic Soil
Authors: Homenauth O. P. , McBride M. B. 
Published: July 2010

AbstractAdsorption isotherms of organic pollutants such as aniline on soil colloidal materials have generally not been described for a wide range of solution concentrations. The characteristics of isotherms for aniline adsorption on Ca‐saturated kaolinite, montmorillonite, vermiculite, and an organic soil were determined for a wide range of aqueous concentrations at acid and neutral pH. Aniline adsorption was greater at acid than neutral pH for all adsorbents, an indication of preferred adsorption of anilinium. Adsorption on montmorillonite, vermiculite, and kaolinite across the aniline concentration range of 1 × 10−4 to 2 × 10−2 M was best described by a sigmoid (S‐type) isotherm, an equation for which was derived from a model of cooperative adsorption, in which aniline was assumed to adsorb in molecular “clusters”. Adsorption on the organic soil across the same wide range of aqueous concentration was not described adequately by the S‐type isotherm, but rather by the Brunauer‐Emmett‐Teller (BET) function. Within the restricted range of low aniline adsorption, the adsorption isotherms were linear for all adsorbents. At somewhat higher (intermediate) aniline adsorption, the isotherms remained linear for kaolinite and vermiculite, but curvilinear (L‐type) isotherms were obtained for montmorillonite and the organic soil. Generally, the equation best describing adsorption data was different in form for each range of adsorption being considered. Fourier‐transform infrared (FTIR) spectroscopy indicated that, at least at low pH and high adsorption levels, aniline‐anilinium complexes adsorbed on all of the adsorbents. Adsorption on clay and organic matter had characteristics of both electrostatic and weak physical bonding.
Carbon‐13 and Nitrogen‐15 Natural Abundance in Crop Residues and Soil Organic Matter
Authors: van Kessel C. , Farrell R. E. , Pennock D. J. 
Published: July 2010

AbstractSpatial variability in the 13C and 15N natural abundance of plant residues (δ13Cresidue and δ15Nresidue) and soil (δ13Csoil and δ15Nsoil) at the landscape scale remains largely unexplored. This 2‐yr study assessed landscape‐scale patterns and investigated topographic and soil factors that control spatial variability. Low values of δ13Cresidue were associated primarily with the lower level and footslope elements, with significantly (P ≤ 0.001) higher (less negative) values in the upper level and shoulder elements. Strong similarities in the spatial patterns observed for δ13Cresidue and δ13Csoil indicate that the 13C content of soil organic matter is largely dependent on δ13Cresidue. Although the δ13C of the crop residues exhibited marked year‐to‐year variability, which reflected genetic differences and variations in growing season precipitation and perhaps N‐fertilization regime, landscape‐scale patterns for δ13Cresidue were similar in both years. These data support the hypothesis that δ13Cresidue varies in response to environmental conditions and also suggest that topographic or hydrologic controls are at work. The presence of a landscape‐scale pattern in δ13Cresidue and δ13Csoil may be expected to have a confounding effect on studies that employ the 13C natural abundance method to detect changes in plant species composition or to estimate the rate of soil organic matter turnover. Spatial patterns for δ15Nresidue and δ15Nsoil indicated that 15N was distributed in an essentially random pattern.
Determining Parameter Precision for Modeling Nitrate Leaching: Inorganic Fertilization in Nordic Climates
Authors: Larocque M. , Banton O. 
Published: July 2010

AbstractMost NO−3 leaching models require the quantification of many parameters. Because the majority of these parameters are difficult to estimate, it is important to know the impact of parameter imprecision to make proper use of a model. A study was performed to identify the relative influence of the parameters in a deterministic NO−3 leaching model (SOILN) used with inorganic fertilization in nordic climates. A sensitivity analysis of the model was performed using parameters related to the N cycle with two reference systems for the parameters corresponding to field sites located in Quebec and in southern Sweden. Results from both sites showed that atmospheric deposits had little influence on NO−3 leaching in agricultural areas in Quebec and Sweden; the variation of parameters related to nitrification also had little impact on NO−3 leaching at the sites studied; parameters used for mineralization, plant uptake, and denitrification had a significant impact on NO−3 leaching in the simulated conditions; parameters related to abiotic factors had a variable influence, depending mostly on soil water contents.
Soil Morphology‐Peoria Loess Grain Size Relationships, Southeastern Minnesota
Authors: Mason J. A. , Nater E. A. 
Published: July 2010

AbstractSoil profiles formed in Peorial Loess in southeastern Minnesota allow further examination of the widely observed morphological variation of loess‐derived soils with distance from the loess source. In these profiles, morphological variables representing depth of clay accumulation and solum thickness decrease with increasing ratios of coarse silt to total silt in the loessial parent material (R2 = 0.574–0.772). Variables representing depth of clay accumulation also decrease with increasing parent material carbonate content (R2 = 0.297–0.585), but the relationship is weaker. Clay accumulation depth increases with increasing parent material clay content, but the relationship is very weak (R2 = 0.044–0.102). The observed relationship between grain size and clay accumulation is consistent across a wide range of organic matter accumulation, although Typic and Mollic Hapludalfs tend to have shallower clay maxima than darker colored Mollisols. In this study area, unlike other regions of the midwestern USA, stronger soil development in the finer loess cannot be attributed to a shallow, perched water table. We hypothesize that abrupt downward increases in grain size at coarse loess sites inhibit downward moisture flux and, over the long term, limit both the depth of soil development and the amount of weathering and clay accumulation.
Response of Buried Mineral Soil Bags to Experimental Acidification of Forest Ecosystem
Authors: Mitchell M. J. , David M. B. , Fernandez I. J. , Fuller R. D. , Nadelhoffer K. , Rustad L. E. , Stam A. C. 
Published: July 2010

AbstractAt Bear Brook Watershed in Maine, H2SO4 and/or HNO3 was added to 15 by 15 m plots (three replicates per treatment) from 1988 through 1990. Total loading above ambient treatments for the 3 yr was 0 (control), 5100 (low S, low N), 10 200 (high S and N + S), and 11 950 (high N) molc ha−1 yr−1. Changes in soil chemistry were evaluated using tension lysimeters and buried mineral soil bags placed below the forest floor before treatments were initiated. Total soil S was highest in the high S treatment (355 mg S kg−1 soil), intermediate in the low S and N + S treatments (314 and 310 mg S kg−1 soil, respectively), and lowest in the low N, high N, and control treatments (278, 275, and 270 mg S kg−1 soil, respectively). Differences in total S were mostly attributed to phosphate‐extractable SO4, although smaller changes in ester sulfate and C‐bonded S were also detected. Low pH and elevated SO4 in solution resulted in increased SO4 in solution resulted in increased SO4 adsorption. There were no differences caused by treatments in N or C constituents in the soil bags, although N was strongly linked with C (r = 0.86). Nitric and sulfuric acid additions lowered soil pH (H2O) from 4.83 in the control to 4.67 and 4.70, respectively. Sulfuric acid treatments increased exchangeable Ca to 0.32 cmolc kg−1 compared with 0.24 cmolc kg−1 in the control, whereas HNO3 treatments decreased Ca to 0.18 cmolc kg−1. A strong correlation (r = 0.94) between exchangeable Ca and base saturation reflected the quantitative dominance of exchangeable Ca among base cations. Similarities in effects of the N + S and the low S treatments were due to identical additions of SO4 and the absence of a marked effect of NO3 additions on the mineral soil. Changes in the chemistry of the buried mineral soil bags can be explained by both the effects of H2SO4 and HNO3 additions as well as pedogenic processes.
Comparison of Saturated Hydraulic Conductivity Measurement Methods for a Glacial‐Till Soil
Authors: Mohanty B. P. , Kanwar R. S. , Everts C. J. 
Published: July 2010

AbstractHydraulic conductivity is the single most important hydraulic parameter for flow and transport‐related phenomena in soil, but the results from different measuring methods vary under different field conditions. To evaluate the performance of four in situ saturated hydraulic conductivity (Ks) measuring methods, Ks measurements were made at four depths (15, 30, 60, and 90 cm) and five locations on a glacial‐till soil of Nicollet (fine‐loamy, mixed, mesic Aquic Hapludoll)‐Clarion (fine‐loamy, mixed, mesic Typic Hapludoll) association. The four in situ methods were: (i) Guelph permeameter, (ii) velocity permeameter, (iii) disk permeameter, and (iv) double‐tube method. The Ks was also determined in the laboratory on undisturbed soil cores collected from all the five sites and four depths. The Guelph permeameter method gave the lowest Ks values, possibly because of small sample size, whereas the disk permeameter and double‐tube methods gave maximum values for Ks with minimum variability, possibly because of large sample size. Maximum variability in Ks values for soil cores at shallow depths may have occurred because of the presence or absence of open‐ended macropores. Estimates of Ks, however, are most comparable for the velocity permeameter and the laboratory method using a constant‐head permeameter.