bluuebunny/crossref_metadata_2025_split huggingface dataset:
Corn and Soybean Cropping Effects on Soil Losses and C Factors
Authors: Alberts E. E. , Wendt R. C. , Burwell R. E. 
Published: July 2010

AbstractGreater soil losses are generally thought to occur with soybean (Glycine max. [L.] Merr.) cropping than with corn (Zea mays L.) cropping. However, runoff and soil losses from corn and soybean cropping systems have been measured simultaneously in only a few studies. The objectives of our study were to evaluate differences in soil and water losses between continuous corn and continuous soybean cropping for conventional, field cultivation, and no‐till methods of tillage; and to evaluate differences between measured cropping and management (C) factors and those in Agricultural Handbook 537, USDA that are currently used in soil conservation planning. These objectives were accomplished by analyzing soil and water loss data from a 7‐yr study conducted on a claypan soil in central Missouri. Cropping differences were evaluated for five seasonal periods based upon cultural operation dates and estimated amounts of canopy cover. Average annual soil loss from soybeans was significantly higher (p <0.01) than that of corn for the conventional and no‐till methods. Seasonal periods having the greatest cropping differences in soil loss were period F (rough fallow), period 12 (30 to 60 d after planting) and period 4 (fall harvest to spring tillage). Annual C factors for soybeans were about two times those of corn for all tillage methods. Measured C factors for all tillage methods were consistently lower than those presented in Agricultural Handbook 537, USDA.
Effects of Two Methods of Timber Harvesting on Microbial Processes in Forest Soil
Authors: Hendrickson O. Q. , Chatarpaul L. , Robinson J. B. 
Published: July 2010

AbstractMicrobial populations and activities in a mature, mixed conifer and hardwood stand were compared with those in similar adjacent stands harvested by conventional (CH) and whole‐tree (WTH) methods. Samples of forest soil (sandy, mixed, frigid Typic Haplorthods) were collected monthly during the first season after harvesting. The NH+4‐N production, measured over the course of 21‐d laboratory incubations, declined in the forest floor of the WTH plot, but increased significantly in mineral soil in both harvested areas. Less than 10% of the NH+4‐N produced was nitrified. Nitrifier and denitrifier populations did not increase during the first year following harvesting, and no significant changes in nitrification activity were noted. Forest floor respiration (measured as CO2 evolved in laboratory incubations) was significantly reduced on both harvested plots relative to the intact stand. Litter bag experiments indicated a reduction in nutrients (N, P, K, Mg) available for decomposer organisms on the WTH plot, and a corresponding reduction in litter decay rates. These effects correspond to reductions in forest floor moisture, water‐holding capacity, and organic matter content after harvesting. In the 0 to 5‐cm mineral soil depth, total bacteria increased on the CH plot but not on the WTH plot. Despite reduced forest floor moisture and nutrient availability, sprouting of trembling aspen (Populus tremuloides Michx.) on the whole tree‐harvested area was vigorous.
Isotopic Triple Labeling in Miscible Displacement Studies
Authors: Nkedi‐Kizza P. , Jackson R. K. , MacIntyre J. L. 
Published: July 2010

AbstractA technique was developed to analyze three beta‐emitter isotopes (45Ca, 36Cl and 3H2O) in a sample, using a two channel liquid scintillation spectrometer. This technique was further successfully used to analyze the concentration of these isotopes in the effluent during miscible displacement studies through columns packed with an Oxisol soil. The isotopic triple labeling approach was used to investigate the effects of physical and chemical properties of the porous medium during solute transport. Tritium was used to study the effects of the physical properties of the porous medium (aggregate size and flux), while 45Ca (a cation) and 36Cl (an anion) were used to study the effects of the chemical properties (solution pH and concentration) of the same porous medium. This is a promising approach to determine how the physical and chemical properties of a soil interact to influence solute transport.
Steady Absorption from Spheroidal Cavities
Authors: Philip J. R. 
Published: July 2010

AbstractExact solutions are given for steady absorption from prolate and oblate spheroidal cavities (or bulbs of saturation). The solutions for the needle, sphere, and disc are special cases. Apart from their direct relevance to systems with gravity negligible, our results yield the leading terms of expansions describing steady infiltration for small and moderate values of the dimensionless cavity (or bulb) length.
Sorption of Copper(II) on Aluminum Hydroxide as Affected by Phosphate
Authors: McBride M. B. 
Published: July 2010

AbstractThe mechanisms of Cu2+ bonding on noncrystalline aluminum hydroxide with or without various levels of presorbed phosphate have been studied by the technique of electron spin resonance. Evidence for two separate chemisorption sites in the absence of phosphate is presented. At high levels of Cu2+ adsorption, discrete site chemisorption is replaced by nucleation or precipitation of hydroxy‐Cu species at the surface. High levels of sorbed phosphate suppress Cu2+ adsorption, blocking the coordination of Cu2+ to AIOH groups on aluminum hydroxide. It is proposed that the decreased adsorption of Cu2+ observed in this study was a result of the weaker coordination of Cu2+ to the phosphate‐coated surface than to the alumina surface in the absence of phosphate. The enhanced adsorption of metal ions on oxide and hydroxide surfaces following phosphate sorption observed in other studies is attributed to a different mechanism, involving the formation of a ternary complex in which Cu bonds simultaneously to phosphate and the surface.
The Occurrence of Extractable Elements in Soils from the Northern Great Plains
Authors: McNeal James M. , Severson R. C. , Gough Larry P. 
Published: July 2010

AbstractThe modes of occurrence of extractable elements from 21 A and C horizon samples of uncultivated soils were examined using R‐mode factor analysis. The extractants (DTPA, EDTA, HCl, hydroquinone, magnesium nitrate, and ammonium oxalate) cover a wide range of chemical attack. Four major elements (Ca, K, Mg, and Na) and eight trace elements (Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn) were determined in each extractant solution. A variety of chemical, mineralogical, and physical variables were also determined on each sample. Four varimax factors (clay, organic, Fe and Mn oxides, and soluble‐Na) accounted for 74.2% of the total variance of the 90 variables for the A horizon. Seven varimax factors (Fe and Mn oxides, clay, CEC, soluble‐Na, organic, Fe and Mn, and plagioclase) accounted for 77.2% of the total variance of the 79 variables for the C horizon. A and C horizon extractable trace elements are most generally related to Fe and Mn oxides, as indicated by loadings on the Fe and Mn oxide factor for both the A and C horizons. Each extractant generally operates on different modes of occurrence of an element in soil. For example, substantial differences occur between the HCl‐, oxalate‐, and hydroquinone‐extractable trace elements. However, the modes of occurrence for trace elements removed by DTPA and EDTA were very similar, suggesting strong relationships between elements dissolved by these two extractants. The modes of occurrence for each individual major element are similar with each of the six extractants. A horizon Ca and Mg, and C horizon K and Mg are strongly related to a clay factor. C horizon Ca and A horizon K are strongly related to the CEC and organic factors, respectively. Both A and C horizon extractable Na are very strongly related to the soluble‐Na factor. These results suggest that extractable major elements are water‐soluble and are associated with the constituents that are responsible for that factor. Consequently, strong relationships should occur for any individual major element dissolved by any pair of extractants.
Long‐term Dryland Crop Responses to Residual Phosphorus Fertilizer
Authors: Halvorson A. D. , Black A. L. 
Published: July 2010

AbstractLittle information is available on the long‐term effects of a single P fertilizer application on grain yields of crops grown on dryland soils deficient in plant‐available P. Therefore, duplicate plots were established in 1967 and 1968 on a Williams loam (fine‐loamy mixed, Typic Argiborolls) with a NaHCO3−extractable P of 6 mg P/kg soil. A split‐plot, randomized complete block design was used with three levels of available N (generally 0, 45, and 90 kg N/ha each crop year) as main plots and a one time application of P fertilizer at rates of 0, 22, 45, 90, and 180 kg P/ha as subplots. During the first crop year, application of 22, 45, 90, and 180 kg P/ha raised the average soil test P levels to 9, 12, 26, and 40 mg P/kg soil, respectively. Soil test P levels 16 yr after P fertilization and 10 or 11 crops harvested avg 5, 6, 7, 9, and 13 mg P/kg soil in 1983 for these same respective P treatments. Soil test P levels declined progressively with each additional crop year until the eighth crop or 13 yr after P application, at which time a new soil P equilibrium level appeared to be developing. Grain yields generally increased with increasing residual soil P level when adequate levels of N, either residual or applied, were present. However, no response to increasing residual soil P level was observed under annual cropping without adequate N. Accumulated grain yields after 10 or 11 crops were about three times greater with both N and P fertilization than with P fertilization alone. The study verifies that adequate available N is required to derive benefit from residual P fertilizer. The long‐term (16 yr) residual benefits from P fertilization suggest a method for possibly satisfying the P needs for several crop years in reduced and notillage systems, if the P is applied and incorporated before initiation of these tillage systems.
Changes in Soil Properties Under Annual Applications of Feedlot Manure and Different Tillage Practices
Authors: Sommerfeldt T. G. , Chang C. 
Published: July 2010

AbstractA long‐term manure study was set up in which cattle feedlot manure was applied annually at four rates to nonirrigated and irrigated land and was incorporated into the soil by plow, rototiller, or cultivator. The soil is a Dark Brown Chernozem (Typic Haploborolls) at the Lethbridge Research Station. The effects of the manure, incorporated by different methods, on the physical properties and organic matter content of the soil were determined. On both nonirrigated and irrigated land, the soil organic matter content of the surface 0 to 15 cm increased with increasing rates of manure application. Spring‐time soil temperatures, at 8‐cm depth, were coldest where the highest rate of manure had been incorporated. Drawbar draft decreased with increasing rates of manure application. Similarly, bulk density of the surface 0 to 15 cm of soil decreased with increasing rates of manure application, the greatest effect being where the manure had been incorporated by cultivator on irrigated land. But, at 15 to 30‐cm depth, the smallest bulk density was where the manure had been incorporated by plow. Increasing rates of manure on irrigated land tended to decrease the amount of aggregates < 1 mm and increase the amount > 1 mm in size, at the 15 to 30‐cm depth. These results indicate that manure, applied at the relatively low rates that are currently recommended, can maintain and increase the organic matter content of the soil and ameliorate the physical condition of southern Alberta soils.
Tillage Effects on Soil Water Retention and Pore Size Distribution of Two Mollisols
Authors: Hill R. L. , Horton R. , Cruse R. M. 
Published: July 2010

AbstractA study was conducted to determine the effects of conservation and conventional tillage on soil water retention and pore size distribution of two mollisols. Two locations were used, each having randomized complete‐block designs with three replications of continuous‐corn (Zea mays L.) plots under no‐tillage, reduced tillage, and conventional tillage. One location, site 1, was in its 2nd yr of tillage experimentation on a Canisteo series soil (Typic Haplaquolls), and the other location, site 2, was in its 8th yr on a Nicollet series soil (Aquic Hapludolls). Undisturbed soil cores were obtained near the planted row at the 5.0‐ to 7.5‐cm and 10.0‐ to 12.5‐cm depths from the two sites. Soil water retention of the soil cores was measured at water matric potentials of 0 to −39.22 kPa. Pore size distribution was estimated by using a capillary model. Statistical differences in soil water retention due to tillage treatments appeared at site 1, with general means comparisons of reduced tillage > no tillage > conventional tillage in the amount of water retained at any matric potential. Reduced tilled soil generally retained a significantly (LSD 0.05) larger quantity of water than conventionally tilled soil. No‐tilled soil was not significantly different from reduced tilled or conventionally tilled soil in its water retention characteristics. Differences in water retention between tillage treatments were not significant at site 2, but trends in the means comparisons similar to those of site 1, were observed. Analysis of variance failed to show significant tillage effects for the pore size distribution regardless of pore radius interval partitioning. Trends indicated that soil under conventional tillage had a larger proportion of its pore volume in pores > 15 µm radii compared with soils under conservation tillage. Conservation tilled soils appeared to have a larger portion of pores in the 15‐ to 0.1‐µm pore radius interval. Implications are that conventionally tilled soils should drain more rapidly than conservation tilled soils and that conservation tilled soils should retain more plant available water than conventionally tilled soils. The data indicate that bulk density increases occurred at the expense of larger pores (>150‐µm radii). Because conventionally tilled soils have the greater proportion of large pores, these soils seem to be more susceptible to densification than the soils under the conservation tillage systems.
Tillage Effects on Bulk Density and Soil Strength of Two Mollisols
Authors: Hill R. L. , Cruse R. M. 
Published: July 2010

AbstractFarmers in the Midwest are concerned that continuous no‐tillage cultivation may be causing soil compaction within their fields. A study was conducted to determine the effects of conservation and conventional tillage on soil bulk density and soil strength of two Mollisols. Two locations, each having randomized complete‐block designs with three replications of continuous corn plots under no‐tillage, reduced tillage, and conventional tillage were used. One location, site 1, was in its 2nd yr of tillage experimentation and the other location, site 2, was in its 8th yr of tillage experimentation. Gamma irradiation was used to determine bulk densities of undisturbed soil cores. Soil strength was determined by using a fall cone penetrometer at soil water matric potentials of 0, −20, and −40 kPa. Tillage treatments did not have a statistically significant effect on bulk density at either site. Bulk density increased significantly with depth for the three tillage treatments at both sites. Tillage treatments had significant effects on soil strength at site 2, but not at site 1. Strength of soil at site 2 under reduced tillage was not significantly different than for soils under no‐tillage, but the soils under both these tillage systems had significantly greater soil strengths than that observed for conventionally tilled soil. The pattern of differences in soil strength due to tillage treatment was the same at site 1, but the differences were not statistically significant. Soil strength increased with decreased matric potential for the three tillage treatments of both sites. Neither bulk density nor soil strength of the soils under any of the tillage systems for the 0 to −40 kPa matric potential range appeared to be large enough to have an appreciable inhibitory effect on plant root growth.
Effects of Tractor Logging on Soils and Vegetation in Eastern Oregon
Authors: Snider Michael D. , Miller Richard F. 
Published: July 2010

AbstractSoil characteristics were investigated on a mixed conifer forest stand in Oregon's Blue Mountains. The most recent logging had occurred on the site 6 yr previously; 1 yr after harvest, slash was machine‐piled and burned. Five classes of ground disturbance including a control were identified, based on degree of soil and ground cover disruption. Bulk density of the disturbed classes was not significantly different from control areas. Infiltration and saturated hydraulic conductivity rates on both disturbed and control areas were high relative to projected storm intensities. Soil organic matter content in the upper 3 cm of disturbed areas was markedly below that of control areas. Understory vegetation production on seeded skid trails was 66% above that of control areas; however, below ground biomass of control areas, vegetated with native rhizomatous species, was three times that of skid trails.
Oxygen Uptake and Transport in Soils: Analysis of the Air‐water Interfacial Area
Authors: Skopp J. 
Published: July 2010

AbstractAeration of soil influences root activity, microbial processes, and chemical reactions. Descriptions of this process have relied on macroscopic concepts which do not allow the incorporation of detailed theories of gas movement. The present study presents a microscopic approach to this problem. Equations are presented to describe the movement of gas. The following parameters are of importance in this theory: gas phase diffusion coefficient, air‐water interfacial area, air‐water transfer coefficient, volumetric water content, gas solubility in water, and gas concentration in solution. These parameters are indirectly dependent on total porosity, air‐filled porosity, temperature, solute composition, or microbial activity. The solution to the governing equations suggests that air‐water interfacial area is an important soil physical property which has a controlling influence on oxygen transport. The dependence upon soil moisture of air‐water interfacial area and flux of gas through the soil surface is examined. The qualitative influence of soil texture on this dependence is also examined.
Determining Soil Hydraulic Properties from One‐step Outflow Experiments by Parameter Estimation: I. Theory and Numerical Studies
Authors: Kool J. B. , Parker J. C. , van Genuchten M. Th. 
Published: July 2010

AbstractThe numerical feasibility of determining water retention and hydraulic conductivity functions simultaneously from one‐step pressure outflow experiments on soil cores by a parameter estimation method is evaluated. Soil hydraulic properties are assumed to be represented by van Genuchten's closed‐form expressions involving three unknown parameters: residual moisture content θ, and coefficients α and n. These parameters are evaluated by nonlinear least‐squares fitting of predicted to observed cumulative outflow with time. Numerical experiments were performed for two hypothetical soils to evaluate limitations of the method imposed by constraints of uniqueness and sensitivity to error. Results indicate that an accurate solution of the parameter identification problem may be obtained when (i) input data include cumulative outflow volumes with time corresponding to at least half of the final outflow and additionally the final outflow volume; (ii) final cumulative outflow corresponds to a sufficiently large fraction (e.g., >0.5) of the total water between saturated and residual water contents; (iii) experimental error in outflow measurements is low; and (iv) initial parameter estimates are reasonably close to their true values.
Nitrification and Characteristics of Nitrifying Microorganisms in an Acid Forest Soil
Authors: Kreitinger J. P. , Klein T. M. , Novick N. J. , Alexander M. 
Published: July 2010

AbstractA study was conducted of factors affecting nitrate (NO‐3) accumulation and characteristics of the nitrifying microflora in the O2 horizon of an acid forest soil (pH 3.6–4.0) from the Adirondacks region of New York. The addition of ammonium (NH+4 did not enhance NO‐3 formation in suspensions of soil, but such an enhancement occurred if the suspensions were amended with peptone or if the soil had been previously leached with distilled water. The effect of additions of NH+4 on NO‐3 production was correlated with the influence of NH+4 on N mineralization. Although levels of 47 µg NH+4‐N/mL stimulated NO‐3 formation in suspensions of leached soil, additions of 94 µg NH+4‐N/mL or more were toxic. The enhancement of nitrification by low concentrations of NH+4 was not accompanied by an increase in CO2 fixation. Nitrapyrin inhibited nitrification in NH+4‐amended but not in unamended suspensions of soil, but it suppressed CO2 fixation in suspensions with and without added NH+4. Nitrapyrin stimulated N and C mineralization. The results show that nitrification in this soil is not the result of classical autotrophic nitrifiers, and a possible role for methylotroph‐type organisms in nitrification is suggested.
Fallow Nitrate Accumulation in a Wheat‐fallow Rotation as Affected by Tillage System
Authors: Lamb J. A. , Peterson G. A. , Fenster C. R. 
Published: July 2010

AbstractThe objectives of this study were to compare NO‐3‐N levels for three tillage systems, and to measure seasonal variation in NO‐3‐N levels during the fallow period of a winter wheat (Triticum aestivum L.) crop‐fallow rotation. The study was conducted on two sites, Duroc loam (Pachic Haplustolls) which was broken from native sod in 1970, and Alliance silt loam (Aridic Argiustolls) which had been cultivated 30 to 40 yr prior to establishment of the experiment, at the High Plains Ag Lab, Sidney, NE.No‐till, stubble mulch, and plow (bare fallow) treatments were established in 1970. In the first 2 yr at the Duroc site, the no‐till and stubble mulch tillage system soils accumulated 64 and 73% as much NO‐3‐N as the plow soil, respectively. Except 1975 and 1980, the NO‐3‐N accumulation from tillage systems from 1974 to 1980 was not different. From 1970 to 1975 NO‐3‐N accumulation in no‐till and stubble mulch soils at the Alliance site was different with no‐till and stubble mulch having 67 and 71%, respectively, as much NO‐3‐N as plowed soils. From 1976 to 1983, except 1981 and 1982, the NO‐3‐N accumulation under the different tillage systems was not different. The fallow portion of the experiments were sampled every 21 d between 1981 and 1983. Neither rate nor the beginning point of accumulation was affected at either site by tillage system. The date during fallow when a soil sample for N fertilizer recommendation was taken was important. A sample taken in July would only have 50 to 60% of the NO‐3‐N found at seeding time.