bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Criteria for Separating Soils with Xeric and Udic Moisture Regimes
Authors: Thomas B. R. , Simonson G. H. , Boersma L.
Published: July 2010

This study was designed to evaluate criteria for classifying soil series in the Coast Range Mountains of western Oregon into categories with xeric and udic moisture regimes. Relationships among soil‐water suction, plant‐water suction, and cambial activity of Douglas‐fir (Pseudotsuga menziesii [Mirb.] Franco) were also evaluated. Soil‐water content was measured with gypsum blocks. Plant‐water suction of Douglas‐fir branch tips was measured with a pressure bomb. These measurements were taken early in the morning at least once every 10 days. Experimentals sites were selected on three soil series and one north slope soil phase tentatively classified as xeric and on four soil series tentatively classified as udic. The four study sites in the xeric zone had soil‐water suctions equal to or greater than 15 bars within the soil‐water control section for at least 60 consecutive days. None of the four study sites in the udic zone were dry that long. Cumulative water deficit in the xeric zone was about 75% of the seasonal total when the entire soil‐water control section attained 15 bars. Almost all available water was removed from the upper third of the profile in the xeric zone when the trees stopped producing springwood. Much less water was removed from the upper third of the profile in the udic zone. The same relationship held true for the available water in the entire profile at time of dormancy. Trees in the xeric zone produced springwood an average of 23 more days and have 26 more days total growing time than trees in the udic zone. Changes of soil and plant‐water suction with time showed similar patterns but different magnitudes. It was concluded that plant‐water suction cannot be used in lieu of soil‐water suction for purposes of soil classification.
Micro‐Determination of Cation‐Exchange Capacity by Neutron Activation Analysis
Authors: Dudas M. J.
Published: July 2010

Neutron activation analysis was evaluated as a method to determine the cation‐exchange capacity (CEC) of clay samples. Cation‐exchange capacity values of satisfactory reproducibility and accuracy were obtained on 5‐ to 50‐mg subsamples of kaolinite and montmorillonite clays previously saturated with Na, Rb, or Cs. use of Cs as the index ion provided the simplest and most flexible conditions for the activation analysis method.
Test of a New Model for the Kinetics of Adsorption‐Desorption Processes
Authors: Griffin R. A. , Jurinak J. J.
Published: July 2010

A new model for the kinetics of adsorption‐desorption processes proposed by Lindstrom, Haque, and Coshow (1970) was tested with adsorption and desorption data for the interaction of phosphate with the calcite mineral surface. The model was found to offer considerable advantages in speed and convenience to those users whose experimental conditions correspond to the assumptions inherent in the derivation of the model. There was reasonable agreement between the predicted adsorption kinetic parameters and experimental data. However, considerable disparity was observed between predicted and experimental desorption parameters. It was concluded that the model was not valid for endothermic processes.
Geomorphic Occurrence of Pelloxererts, Willamette Valley, Oregon
Authors: Parsons R. B. , Moncharoan L. , Knox E. G.
Published: July 2010

Documentation of the time factor in the genesis of Vertisols in western Oregon is provided by this study of Bashaw soils on four geomorphic surfaces that range in age from Holocene to middle Pleistocene. Bashaw soils are in a very fine, montmorillonitic, mesic family of Typic Pelloxererts. Although these soils have slickensides and high clay contents, they lack gilgai microrelief and tonguing between the A and C horizons. Stratification in the parent alluvium has not been obliterated by churning, suggesting that one annual cracking and closing cycle will not produce all of the morphological features commonly associated with Vertisols. Pedons from surfaces only 550 years old have developed sufficiently to be classified as Xererts. Morphological, chemical, and physical data indicate that the pedons studied are similar enough to lie within the range of one soil series. This study shows that Xererts occur on very young landscapes and that very little change takes place with increasing age.
Effect of Long‐Term Management on Physical and Chemical Properties of the Coshocton Watershed Soils
Authors: Edwards W. M. , McGuinness J. L. , Van Doren D. M. , Hall G. F. , Kelley G. E.
Published: July 2010

After 30 years of differential treatment, 0.7‐ to 3.2‐ha watersheds in improved management (contouring, recommended fertilization and pH level, alfalfa in rotation) had higher crop yields and less runoff and erosion than watersheds under prevailing management. Soil samples were taken from the topsoils, plowsoles, and B horizons of the watersheds to determine the effect of such management on soil physical and chemical characteristics.

Large changes in chemical characteristics resulted from the higher fertilization associated with improved management but the changes generally did not persist below the topsoil layer. Measurable differences in physical characteristics of the watershed soils were slight and were confined to the topsoil layer. Differences in crop yield and hydrologic performance are attributed to fertilization, crop growth, and tillage differences associated with the two levels of management.
Grain Sorghum Response to Iron in a Ferrous Sulfate‐Ammonium Thiosulfate‐Ammonium Polyphosphate Suspension
Authors: Mortvedt J. J. , Giordano P. M.
Published: July 2010

Forage yields and Fe uptake by grain sorghum (Sorghum bicolor L., Moench) from a band application of a FeSO4‐ammonium polyphosphate suspension in a greenhouse pot experiment on a calcareous soil were doubled over those of the polyphosphate alone. Inclusion of (NH4)2S2O3 with this mixture resulted in another 15–25% increase in crop response. Extraction of soil around the fertilizer bands after harvest showed that inclusion of (NH4)2S2O3 resulted in increased Fe movement from the fertilizer band. Band placement of fertilizers containing (NH4)2S2O3 must be at least 3 cm from the seed to prevent toxicity to emerging seedlings.

In a laboratory study with the same soil, inclusion of (NH4)2S2O3 with a FeSO4‐ammonium polyphosphate fertilizer resulted in a decrease in the level of 0.5N HCl‐extractable Fe in the soil around the fertilizer band and concomitant increases in the 1‐1.5 and 1.5‐2 cm zones, indicating increased diffusion of the applied Fe from the fertilizer band. Application of (NH4)S2O3 alone or with a polyphosphate fertilizer to soil resulted in increased levels of extractable Fe2+, suggesting that (NH4)2S2O3 also reduced some soil Fe for a short period after soil application.
Gamma Radiation Measurements of Bulk Density Changes in a Soil Pedon Following Irrigation
Authors: Reginato Robert J.
Published: July 2010

Bulk density in a soil pedon was measured with a gammaray transmission technique utilizing 137Cs and 241Am. Both gamma‐ray sources could not be used simultaneously for bulk density determinations in a system where the sources were uncollimated and the detector was not shielded. By alternating sources for each scan down the soil profile, it was shown that bulk density decreased in the top 6 cm of soil about 30 minutes after water was ponded on the soil surface. As soon as the water drained from the surface, bulk density values approached preirrigation levels. Changes in height of the soil surface upon irrigation corresponded with changes in bulk density.
Artificial Weathering of Oxidized Biotite: III. Potassium Uptake by Subterranean Clover
Authors: Gilkes R. J. , Young R. C.
Published: July 2010

Potassium uptake from biotites by subterranean clover decreased as the proportion of oxidized Fe in octahedral sites increased. The relative availability of K from sequentially oxidized biotites may be predicted by sodium tetraphenylboron extraction.

No major changes in mica structure due to removal of interlayer K by plants were detected.
Azide and Ethylenethiourea Mobility in Soils
Authors: Helling Charles S. , Thompson Susan M.
Published: July 2010

A masking technique was developed for visualizing nonradioactive compounds on soil thin‐layer chromatographic plates. To determine azide mobility, leached plates were sprayed with a kaolinite slurry in 95% ethanol, air‐dried, and resprayed with 2% Fe(NO3)3 in 5% HNO3. The average RF of azide in four mineral soils was 0.87, and in a muck 0.21; it is thus quite mobile in most soils. The form of azide (NaN3, KN3, or KN3 + K2CO3) did not affect mobility. 2‐Imidazolidinethione (ethylenethiourea, or ETU), a degradation product of ethylenebis (dithiocarbamate) fungicides, was evaluated after masking with kaolinite + alumina (1:2), sprayed onto soil plates in 95% ethanol. Nitroprusside and Grote's reagents were useful chromogenic reagents. Mobility was also determined by autoradiography of [14C]ETU; average RF's for four mineral soils ranged from 0.83 to 1.00, decreasing to 0.61 in a muck. Although weakly adsorbed from solution, ETU is immobilized by drying the soil before leaching. 2‐Imidazolidone (ethyleneurea) and possibly sulfur were detected in soil incubated 7 days with ETU.
Plant Availability of Native and Added Potassium in Undried Soils
Authors: Suarez‐Hernandez Arturo , Hanway J. J.
Published: July 2010

Undried surface and subsurface samples from 15 soils in Iowa were analyzed in the laboratory and used for a greenhouse experiment. K2SO4 was added to the soil samples at rates of 0, 50, 100, 150, and 200 ppm K. Increases in NH4OAc‐exchangeable K due to the K fertilizer additions were equivalent to 49 to 80% and 18 to 78% of the added K in the soil samples from the 0–15 and 30–45 cm depths, respectively. Percentages of K in the first harvest of ryegrass (Lolium multiflorum) were highly correlated, R2 = 0.89**, with the amounts of exchangeable K in the undried soil samples with and without additions of fertilizer K. Total plant uptake of K in six ryegrass harvests from soil samples without added K2SO4 was highly correlated with and generally greater than 2.67 times the amount of exchangeable K initially present in the soil samples. Added K2SO4 resulted in increases in total plant uptake of K equivalent to 42 to 97% of the added K. At a given level of exchangeable K, percentages of K in the first harvest of ryegrass grown on undried calcareous soil samples were higher than in grass grown on noncalcareous soil samples.
Geomorphic Relationships of Oxisols and Ultisols on Kauai, Hawaii
Authors: Beinroth F. H. , Uehara G. , Ikawa H.
Published: July 2010

A succession of Eutrustox‐Eutrorthox‐Gibbsiorthox‐Gibbsihumox occurring in northeastern Kauai, Hawaii, is shown to be a climosequence. These soils developed synchronously on basic lavas forming one geomorphic surface of Pleistocene age. Ultisols found along the knickpoint of this surface to recent erosion surfaces are the result of soil creep. The mechanisms of clay mobilization by soil shear caused by creep are discussed.
Charge Characteristics of Soils as Affected by Phosphate Sorption
Authors: Sawhney B. L.
Published: July 2010

The increase in cation exchange capacity (CEC) of six Connecticut soils varied from 11 to 88% on phosphate sorption from dilute solutions. As the phosphate sorbed increased, the exchange capacity also increased. The amount of P required to produce an increase of 1 meq in CEC varied with pH; at pH 5, 80 mg P was required for an increase of 1 meq in CEC while at pH 7.5, only 40 mg P was required for the same increase. The increase in CEC at pH 5 is attributed primarily to the replacement of octahedrally coordinated water molecules on sesquioxide surfaces while at higher pH values, replacement of hydroxyl ions by phosphate ions becomes more important.
Anion Adsorption by Allophanic Tropical Soils: II. Sulfate Adsorption
Authors: Gebhardt H. , Coleman N. T.
Published: July 2010

Volcanic ash‐derived soils (Andepts) from Mexico, Colombia, and Hawaii have large capacities for sulfate adsorption: 10–20 meq/100 g for surface soils and 15–60 meq/100 g for subsoils. The sulfate adsorption capacity is pH‐dependent. For a typical case, B‐horizon material from San Gregorio, Michoacan, Mexico, capacity in meq/100 g was 13 at pH 6.3, 22 at pH 5.1, 38 at pH 4.4, and 48 at pH 4.1. Sulfate adsorption was accompanied by and dependent upon the simultaneous adsorption, or consumption, of protons. Increasing solution concentration of sulfate beyond 5–10 meq/liter at a given pH resulted in relatively minor additional uptake by the soil. At a given pH, sulfate adsorption capacities, expressed as mmole/100 g soil, nearly equaled Cl adsorption maxima. This, together with the consumption of 1 meq H for each mmole of HCl or H2SO4 adsorbed, suggests that the two anions are adsorbed on the same sites and that site protonation is a prerequisite for adsorption.

Sulfate adsorbed by the San Gregorio soil at pH 4 was strongly bound against hydrolysis (removal by water leaching) and was only partly displaced by 1N KNO3. It was completely displaced by 1N NH4OAc, pH 7. Sulfate may be adsorbed by Andepts, specifically, by ligand exchange. Its affinity for soil is at least 10 times that of nonspecifically adsorbed anions such as Cl and NO3.
Comparison of Soil Carbohydrate in Several Prairie and Forest Soils by Gas‐Liquid Chromatography
Authors: Folsom B. L. , Wagner G. H. , Scrivner C. L.
Published: July 2010

Soil carbohydrate in thirteen different profiles was investigated using gas‐liquid chromatography to identify and determine quantities of monosaccharides released by acid hydrolysis. Total quantities of monosaccharides extracted by sulfuric acid were positively correlated with organic carbon for the soils studied. Differences in monosaccharide determined for the various profiles related to the influence of native vegetation and parent material. Generally high concentrations of monosaccharides occurred in the Al horizons of forested soils, while the prairie soils which had thicker surface layers contained the larger total quantities. Total monosaccharides accounted for from 9 to 24% of organic carbon. Where the influence of vegetation and parent material on development was similar for a sequence of soils, those showing a greater degree of weathering had a lower proportion of the organic carbon occurring as saccharides. Glucose, galactose, and mannose were the predominant sugars in all soils and glucose was always present in the greatest amount. Appreciable quantities of arabinose and xylose were present in all soils, and small amounts of rhamnose, fucose, and ribose were found. Changes in distribution of the various monosaccharides with depth in the profile were noted, the most consistent of which was that the amount of mannose relative to total measured carbohydrate increased with depth. There were proportionately more pentoses than hexoses in the prairie soils than the forest soils.
Losses of Nitrogen and Mineral Nutrients from Corn Grown in Greenhouse Pot Experiments
Authors: Terman G. L. , Allen S. E.
Published: July 2010

Three greenhouse pot experiments were conducted: the first to compare rates of N as ammonium nitrate (AN) and S‐coated urea products (SCU, 6 and 12% initial dissolution in water) for corn (Zea mays L.); the second to measure dissolution of SCU‐5, SCU‐12, and SCU‐20 in uncropped soil; and the third to compare rates of N, P, and K for corn. Accumulation by and subsequent losses of nutrients from corn tops and roots at three harvest dates were measured. Significant losses of N, P, and K from corn tops or tops + roots fertilized with high rates of N as AN and SCU‐12 or of P and K occurred during growth from 6 to 8 or 9 weeks. These losses were closely associated with reduction in growth rates resulting from depletion of N, P, or K under test. No appreciable nutrient losses occurred from slower growing plants fertilized with SCU‐6. Three SCU products released N in uncropped cultures over a 9‐week period. Leaching of nutrients from corn top growth by guttation, dew, or rain was not a factor in these experiments. Consequently, most of the losses were through the roots. Competition by growth of microorganisms stimulated by root exudates is a probable explanation.
Picloram Sorption by Soils
Authors: Farmer W. J. , Aochi Y.
Published: July 2010

Picloram (4‐amino‐3,5,6‐trichloropicolinic acid) adsorption‐desorption isotherms were derermined on six western USA soils. Adsorption isotherms were determined as a function of temperature, soil/solution ratio, and solution ionic strength. Special attention was given to the effects of pH and organic matter content in the analysis of the result. Adsorption increased with increasing organic matter with soils varying in organic matter content from 0.94% to 4.2%. Variations in adsorption between soils were not correlated with clay content or soil pH in the pH range 5.6 to 7.4, but increased adsorption resulted with decreasing solution pH of any individual soil. Sorption was described by the Freundlich isotherm at equilibrium concentrations less than 20 µg/ml. Temperature had only a slight effect on adsorption by the three soils examined. Increasing temperature from 10 to 20 to 30C generally resulted in decreased adsorption. Increasing the soil/solution ratio from 1:5 to 1:2 increased the Freundlich k value for the five soils tested. Freundlich k values were higher for the desorption isotherms than for the adsorption isotherms for all six soils. Increased adsorption with increasing ionic strength was predictable from associated pH changes and the dissociation constant for picloram.
A Double Buffer Method for the Determination of Lime Requirement of Acid Soils
Authors: Yuan T. L.
Published: July 2010

A buffer method to take into consideration both the acidity and buffering property of individual acid soils was investigated. The buffer was composed of tris, imidazol, chromate, and pyridine in a 0.2M CaCl2 solution. It was prepared so that each addition of 0.1 meq of a strong acid to 50 ml of this buffer would reduce the pH by 0.1 unit within the pH range of 8.0 and 5.4. Two buffers of the same composition, one adjusted to pH 7.00 and the other to pH 6.00, were added to two separate soil samples. After shaking for 1 hour the pH was determined. The depression of the buffer pH measured the soil acidity neutralized to the equilibrium pH in these systems. The soil acidity to be neutralized from the equilibrium pH to the desired pH was determined by the buffering property of soil which, in turn, was defined by dividing the difference in soil acidity neutralized in the two buffer systems by the difference of the two equilibrium pH values. This is to represent the acidity released by the soil at each increment of pH. The lime required to raise the soil to the desired pH was calculated from the sum of these two acidity portions. The results from this method were highly correlated with and comparable to those by the lime incubation and BaCl2‐triethanolamine methods.
Interaction of Potassium in the Availability and Uptake of Iron From Ferric Hydroxide
Authors: Oertli J. J. , Opoku A. A.
Published: July 2010

The uptake of iron from ferric hydroxic by corn plants (Zea mays L.) was stimulated by the presence of increasing levels of potassium sulfate. Potassium nitrate had a much smaller effect. During the 48‐hour absorption experiments, the pH of the SO4 solution dropped from 9.2 to nearly 4, while that of the NO3 solution dropped only from 8.4 to between 6.5 and 6.8. The different behavior of the two solutions must be due to different imbalances of cation and anion uptake. Nitrate is taken up at a rate similar to that of K, which is faster than that of SO4. Thus NO3 causes a smaller decline of the pH. Reduced pH has a favorable effect on Fe solubility. The phenomenon was also observed (i) in CaCO3‐buffered solutions, in which case the pH drop in the root boundary zone may have been important and different from that in the buffered bulk solutions, and (ii) when Fe was present together with a synthetic cation exchanger.
The Amount and Nitrogen‐15 Content of Nitrate in Soil Profiles from two Central Illinois Fields in a Corn‐Soybean Rotation
Authors: Feigin Amos , Shearer Georgia , Kohl Daniel H. , Commoner Barry
Published: July 2010

This paper reports the concentration and the δ15N (per mill 15N excess) of nitrate present in soil cores as a function of depth and time. The cores were taken at approximately monthly intervals from two central Illinois fields which were in a corn and soybean rotation.

During the period of October 1971 through April 1972, the mean δ15N value of nitrate present at all depths of both fields was + 1.2 ± 1.5. The most striking variation from this mean occurred after the application, on 4 May 1972, of anhydrous ammonia to the field being sown to corn, when a dramatic decrease was observed in the δ15N values of the nitrate in the 0–30 layer of that field. The difference in the δ15N values of the nitrate found in the two fields disappeared after about 2 months. The δ15N values of the ammonium ion found in the soil after application of fertilizer increased with time as the concentration of ammonium decreased and the concentration of nitrate increased. These observations indicate that the observed changes following fertilization in δ15N of nitrate were due primarily to isotopic discrimination associated with incomplete conversion of ammonium to nitrate. The δ15N values of the nitrate in both fertilzed and unfertilized fields were higher in late summer than in the period October to May.

The nitrate content of the 150‐cm profile did not show significant variation with time in either field from October 1971 until 4 May 1972, when anhydrous ammonia was applied to the field being sown to corn. The nitrate concentration in the soil profiles of both fields decreased during the period of crop growth. Fertilizer application and crop uptake appeared to exert a larger influence on the total amount of nitrate in the soil profile than did movement of nitrate out of the 150‐cm profile by leaching, since rainfall in amounts sufficient to redistribute the nitrate within the profile did not lower the total amount of nitrate in the profile.
A Capillary Tube Diffusion Cell for Measuring Ion Diffusion in Aqueous Solutions
Authors: Brown D. A.
Published: July 2010

A capillary tube diffusion cell unit with directions for its preparation and use in measuring ion diffusion in aqueous solutions is described. Self‐diffusion data for Sr, Rb, and Na in single and mixed ion systems and one herbicide, metribuzin (14C) are reported. Values can be routinely obtained with coefficient of variations below 3%.
Effect of Phosphate Adsorption on the Cation‐Exchange Capacity of Volcanic Ash Soils
Authors: Schalscha E. B. , Pratt P. F. , Soto D.
Published: July 2010

The CEC of five subsoils derived from volcanic ash (Trumao soils) in southern Chile was measured following treatment with phosphate solutions with concentrations ranging from 0.0042 to 0.416 moles KH2PO4/liter. The average ratio of increase in CEC to P reacted was 0.6 with only small variations among soils.
Diffusion of Herbicides in the Adsorbed Phase
Authors: Scott H. D. , Phillips R. E. , Paetzold R. F.
Published: July 2010

Equations were presented which describe the diffusion of the soil‐adsorbed herbicide phase. Assuming (i) no precipitation and volatilization, (ii) a linear adsorption isotherm, and (iii) no net change in herbicide concentration in the adsorbed phase, the data needed to make such a calculation can be determined experimentally and are as follows: soil bulk density, distribution coefficient, apparent self‐diffusion coefficient of the herbicide in soil, self‐diffusion coefficient of the herbicide in water and the transmission factor. The results indicated that the magnitude of the diffusion coefficient of metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazin‐5(4H) one] in Dubbs soil depends primarily upon the amount in the adsorbed phase and on the moisture content. The magnitude of the adsorbed phase diffusion coefficients of 14C‐metribuzin was less than the apparent self‐diffusion coefficients and decreased with decreasing soil water content. Since negative adsorbed phase diffiusion coefficients were observed at the lower soil water contents, the data suggested that the amount of metribuzin in the adsorbed phase increased as soil water content decreased.
Degradation of Argillic Horizons in Udalf Soils of New York State
Authors: Bullock P. , Milford M. H. , Cline M. G.
Published: July 2010

Interfingering of albic material into the upper part of argillic horizons in Udalfs of New York is interpreted as evidence of degradation by loss of clay proceeding from the top of the horizon downward and from the surfaces of peds inward. These conclusions are based on: (i) albic material lacking oriented clay surrounding ped centers that contain oriented clay; (ii) the volume of albic material decreasing with depth; and (iii) the albic interfingering being least in soils in which high carbonate content is believed to have delayed clay translocation or weathering. The absence of clay skins in the degrading zone—in contrast with thick clay skins rich in fine clay at the Bt‐C horizon boundary—suggests that part of the clay removed at the top is translocated to the bottom of the B horizon. Smaller amounts of inherited mica clays and larger amounts of vermiculite, intergradient clays, and amorphous material in the clay fractions of degraded zones than in the remainder of B horizons indicates some weathering, but losses by this mechanism are believed small.
Splash Erosion: Some Observations on the Splash‐Cup Technique
Authors: Kinnell P. I. A.
Published: July 2010

Experiments under artificial rainfall conditions showed that the initial, excessive loss from the type of splash cup frequently used in splash‐cup experiments was attributable not only to material being pushed sideways over the edge of the cup by the impact of drops near the perimeter of the exposed surface, but also to a decrease in the rate of splash loss.

The amount of excess material lost during this initial period was not significantly influenced by the frequency of drop impact, but was significantly influenced by the force of drop impact. Consequently, it is unlikely that the effect was attributable to changes in the hydraulic conditions within the erodible material, but may have been attributable to changes in the roughness of the exposed surface. A calibration, specific to the size, shape and velocity conditions of the impacting drops, may therefore be required where the initial loss makes a significant contribution to the total loss from a splash cup. It is also probable that such a calibration may also be specific to the physical nature of the erodible material and to the hydraulic characteristics of the splash‐cup system.
Effect of Effluent from Beef Feedlots on the Physical and Chemical Properties of Soil
Authors: Hinrichs D. G. , Mazurak A. P. , Swanson N. P.
Published: July 2010

Effluent from beef feedlots was applied as irrigation to a Colo silty clay loam soil in eastern Nebraska over a 2‐year period. Atlas sorghum [Sorghum bicolor L. (Moench.)] was grown in 1971 and 1972. Weekly irrigations applied during the growing season were: no effluent or water, 2.5 cm water from creek, 5.0 cm water from creek, 2.5 cm effluent, and 5.0 cm effluent. Surface soil samples were taken just before, midway, and at the end of each irrigation season.

The effluent applications produced no statistically significant differences in soil bulk density, water‐retention characteristics, or size distribution of particles and water‐stable aggregates. Significant differences were measured in the hydraulic conductivities of disturbed soil samples. The effluent reduced the permeability of soil. The electrical conductivities and Na+, K+, and Cl‐ in the leachates obtained from hydraulic conductivity determinations for the effluent‐treated plots increased during the growing season. However, leaching from winter rains essentially eliminated these increases except for K+ which was greatly reduced.
Nitrate Production in Two Forest Soils and Nitrate Reduction in Pine
Authors: Theobald W. F. , Smith W. H.
Published: July 2010

Acid forest soils showed low capacities for nitrification even when substrate NH4‐N was increased. Under forest soil pH conditions and NO3 levels typical of the lower coastal plain, pine roots (Pinus spp.) possessed low nitrate reductase (NR) activities.

An in vivo assay showed NR activity in slash pine roots (P. elliottii Englm. var. ‘elliottii’). Activity depended on NO3 level and pH of nutrient solution. Highest activity was with 100 ppm NO3‐N at pH 6. Ammonium‐grown seedlings possessed low levels of activity even at pH 4, indicating constitutive nature or early induction of the enzymes. Radicles of seeds aseptically germinated actively reduced NO3, indicating activity within the root tissues. Daily patterns of fluctuation in NR activity similar to the pattern for photosynhesis were observed. In vitro assay attempts were unsuccessful, due apparently to the presence of inhibitors.
An Improved Procedure for Sampling the Atmosphere of Field Soils
Authors: Roulier M. H. , Stolzy L. H. , Szuszkiewcz T. E.
Published: July 2010

An improved gas probe for sampling the atmosphere of field soils and the equipment used to install it are described. The probe is easily inserted to depths of a meter or more without significant disturbance of the crop or soil and plugging by soil and water can be cleared without removing the probe from the soil. In medium‐ and coarse‐textured soils this system is more useful than other capillary probe sampling systems because of the method of installation, the strength of the probe, and the depth to which it can be inserted. In poorly structured, finetextured soils where gas samples are difficult to withdraw because of low air permeability, a well‐type probe is more satisfactory.
A Simple Gas Chromatographic Method for Separation of Gases in Soil Atmospheres
Authors: Blackmer Alfred M. , Baker J. H. , Weeks M. E.
Published: July 2010

A simple method is described for the separation of mixtures of CH4, N2O, CO2, N2, and O2 in soil atmospheres using a single sample. This method uses two columns of Porapak Q at different temperatures but requires only one detector and recorder. Total analysis time is 23 min, but samples can be injected every 17 min without conflicting peaks.
Water Transport Through Plant Cells and Cell Walls: Theoretical Development
Authors: Molz Fred J. , Ikenberry Ernest
Published: July 2010

An increasing body of experimental evidence indicates that cell walls constitute an important pathway for water movement through plant tissues. Therefore, the present paper develops a mathematical description of water transport which allows for a water flux in the cell walls that does not necessarily traverse the cell membranes. The result is two coupled diffusion equations, one describing flow in the cell wall pathway and the other describing flow in the parallel cell to cell pathway. Using a resistance‐capacitance network analogy, the various parameters in the governing equations are identified as per cell resistances to water flow and per cell water capacities in and between the two parallel pathways.

The theory is applied to a hypothetical water transport process in a sheet of plant tissue. A general closed‐form solution to the governing equations is obtained in the form of two double Fourier series, and realistic values are obtained from the literature for the various parameters. The theory predicts tentatively that water flows in the cell to cell and cell wall pathways will be comparable in magnitude and highly coupled, with each cell remaining in local equilibrium with the wall material external to its membrane. In this case, the overall transport process can be described by a single diffusion equation which is derived along with an expression for the free energy diffusivity of the combined pathways. The results of this study are in agreement with and bring together several past experimental studies by showing that a significant portion of the water flux traversing a plant tissue can occur in the cell wall pathway with the overall flow process still obeying simple diffusion kinetics. Whenever this occurs, the mathematical treatment of water transport in plant tissue will be simplified considerably.
Soil Strength and Porosities Associated with Cropping Sequences
Authors: Cary J. W. , Hayden C. W.
Published: July 2010

The effects of cropping sequences on the strength and porosity of the Portneuf silt loam soil were studied in south‐central Idaho under normal field conditions. Undisturbed soil cores were collected from the surface 20 cm of seven fields with cropping histories ranging from continuous pasture to continuous beans (Phaseolus vulgaris L.). The soil in all fields was a uniform silt loam developed under arid conditions. The pore size distribution and soil hardness were measured on the undisturbed cores as well as on bulk samples collected from each site. The results indicated that both the pore size distribution and the hardness are rather independent of cropping history. While both these parameters can be changed by mechanical manipulation, the soil soon reverts back to a stable range of values under field conditions.
Nitrification Inhibitor Studies of Soil in Field‐Buried Polyethylene Bags
Authors: Boswell Fred C. , Anderson O. E.
Published: July 2010

Samples of Davidson scl soil, contained in polyethylene bags, were treated with N‐SERVE, a nitrification inhibitor, and buried during the course of fall bedding to a depth commensurate to normal practices for fall applied fertilizer. N‐SERVE effectively inhibited nitrification in these soil samples for a 4‐month period during winter and early spring whereas, in untreated samples, nitrification proceeded throughout the test and added NH4‐N was completely nitrified during the same period.
Determination of Wetting Front Suction in the Green‐Ampt Equation
Authors: Mein R. G. , Farrell D. A.
Published: July 2010

Interest in the Green‐Ampt equation to predict infiltration rates into uniform and layered soils has increased in recent years. The work reported here is a study of the theoretical justification of determining the suction (at the wetting front) parameter in the equation from the hydraulic conductivity versus capillary suction relationship for the soil. It is shown that the wetting front suction so determined and used in a form of the Green‐Ampt equation which allows for the surface boundary condition initially being one of constant flux gives predictions of infiltration volumes comparable to those determined by numerical solution of the complex partial‐differential equation of moisture flow.
Nomographic Interpretation of Water Absorption Data in Terms of a Two‐Parametric Diffusivity‐Water Content Function
Authors: Stroosnijder L. , Bolt G. H.
Published: July 2010

An exponential extrapolation of a set of experimentally determined diffusivities, D as a function of water content, θ, into the region near saturation lead to an underestimate of the water absorption. A two‐parametric expression for the diffusivity as a function of θ, as proposed by Ahuja et al. (1972), is used to construct a nomogram. This provides a connection between the standardized D‐θ relationships according to Ahuja et al. and certain “integral” properties of the absorption wetting front. Good agreement is obtained between experimentally determined diffusivity values and the values derived from the nomographical interpretation of water absorption data. The present approach also lends itself to the construction of families of scaled wetting curves. Thus absorption behavior for different (uniform) initial moisture contents could be predicted adequately.
Ion Association in the Ammonia—Carbon Dioxide—Water System
Authors: Marion G. M. , Dutt G. R.
Published: July 2010

The stability constants for the ammonium bicarbonate and carbonate ion‐pairs were determined in dilute aqueous solutions. For the reaction, NH4 HCO30 ⇄ NH4+ + HCO3‐, K = 1.45. For the reaction, NH4CO3‐ ⇄ NH4+ + CO32‐, K = 4.54 × 10‐2. In the aqueous solutions examined, from 6 to 7% of the total nitrogen and from 6 to 12% of the total carbon were present as ion‐pairs.
Aluminum Content of Soil Extracts as a Function of pH and Ionic Strength
Authors: Misra U. K. , Blanchar R. W. , Upchurch W. J.
Published: July 2010

The concentration of aluminum in the soil extract cannot presently be predicted from ion activity product considerations alone. Aluminum concentration in solution can be estimated from pH and ionic strength of a soil extract by the following empirical equations
urn:x-wiley:03615995:saj2sssaj197403615995003800060020x:equation:saj2sssaj197403615995003800060020x-math-0001

The aluminum concentration in the extracts of several soils were calculated using published data for pH and ionic strength and compared with the experimentally determined values.
Influences of Muleh Rate and Slope Steepness on Interrill Erosion
Authors: Lattanzi A. R. , Meyer L. D. , Baumgardner M. F.
Published: July 2010

Soil and water losses from plots representing field areas between rills were studied for four rates of straw mulch at four slope steepnesses. Three simulated rainstorms totaling 2 hours at 6.4 cm/hour were applied to a 61‐ by 61‐cm test area of Russell silt loam soil.

Interrill erosion was reduced about 40% by mulch applied at a rate of only 0.5 metric tons/ha and about 80% by 2 tons/ha, as compared with no mulch. Erosion was negligible at the 8 tons/ha rate. Soil losses from the interrill areas at 20% slope were only about double those measured at 2% slope, whereas widely used erosion equations show that total field erosion would increase about 20‐fold over this range of steepnesses.

Water loss by runoff was independent of slope steepness, but it was slightly reduced by mulch at a rate of 2 tons/ha and was greatly reduced by the 8 tons/ha rate. After 40 minutes of rainfall, sealing of the soil surface by raindrop impact had reduced infiltration rates for treatments with 0 to 2 tons/ha of mulch to only 20% of those with 8 tons/ha.
Site Factors and the Net Primary Productivity of Young Loblolly Pine and Slash Pine Plantations
Authors: Nemeth J. C. , Davey C. B.
Published: July 2010

The relationship between site factors and net primary productivity of young plantations of loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) in Beaufort County, North Carolina were investigated. Exchange acidity, cation exchange capacity, pH, Mg, and K of these Ultisol and Alfisol soils of the fine‐loamy, mixed, thermic family were found to be correlated (P = 0.05) with the net primary productivity of loblolly pine. The net primary productivity of slash pine was correlated with cation exchange capacity (P = 0.05).
Effects of Phosphorus on Some Physical and Chemical Properties of Clays
Authors: Lutz J. F. , Haque Inamul
Published: July 2010

Montmorillonite, kaolinite, and a 1:1 mixture of them were treated with phosphorus at rates as high as 1,600 ppm using phosphoric acid and monocalcium phosphate. After 3 months the clays were examined for pH, zeta potential (charge), swelling, hydration in suspension, modulus of rupture of briquets, and water retention at 5 and 15 bars pressure. The H3PO4 decreased pH in all clays; the CaH4(PO4)2 decreased it in montmorillonite and in montmorillonite‐kaolinite, but increased it in kaolinite. Both sources of phosphorus caused alternate increases and decreases in the charge of the clays at rates up to 200 ppm and swelling and hydration of the clays were closely correlated to the charge. In general, water retention at 5 bars alternately increased and decreased with increasing rates of phosphorus but did not always exactly parallel the changes in charge, hydration, and swelling. The highest rate (1,600 ppm) caused a significant decrease in the 5‐ and 15‐bar percentages in all instances except the H3PO4 on kaolinite. This exception may have been due to chemical alteration of the kaolinite produced by the very low pH. Modulus of rupture was significantly reduced by both sources of phosphorus. Essentially all of the P‐induced physical and chemical changes would be beneficial in agricultural soils, and they are economically important because the greatest changes were produced by feasible rates of phosphorus.
Bonding of Calcium and Potassium by Vermiculite and Kaolinite Clays as Affected by H‐clay Addition
Authors: Baweja A. S. , McLean E. O.
Published: July 2010

The < 2 µm fraction of Libby vermiculite and Peerless kaolinite was separated and H‐saturated by resin treatment. The H‐clay suspensions were immediately saturated with either Ca or K by addition of the respective hydroxides. Six reciprocal Ca‐K saturations of each clay were prepared by mixing the Ca‐ and K‐clays in appropriate amounts. Increments of H‐clay were added to lower the base saturation and thereby inactivate the pH‐dependent charges. Radioisotopes, 45Ca and 86Rb, were used as tracers for Ca and K, respectively. Two‐phase Donnan‐type systems were prepared and equilibrated for 23 days. Radioactivity in both phases was then assayed and the amounts of Ca and K retained in the suspension phases of the two clay systems computed.

The pH‐dependent fraction of the total CEC was 6.9 and 18.0% for vermiculite and kaolinite, respectively. Additions of H‐clay increased the bonding of both Ca and K as indicated by greater clay‐phase retention. However, maximum retention of the cations at all Ca‐K saturation ratios did not occur when the amounts of H‐clay added equaled the pH‐dependent charge fraction of the clay as had occurred with bentonite and illite.
Boron, Calcium, and Potassium Interactions in Spanish Peanuts
Authors: Hill W. E. , Morrill L. G.
Published: July 2010

Experiments were conducted in the field and greenhouse to evaluate interactions between application of B, Ca (gypsum) and K upon yield and quality of ‘Comet’ variety Spanish peanuts (Arachis hypogaea). In the greenhouse, using Eufaula fine sand, peanuts received factorial treatment combinations of three rates of B (0, 0.25, and 0.50 ppm), three rates of Ca (0, 88, and 176 ppm as gypsum), and three rates of K (25, 50, and 100 ppm). Factorial treatment combinations of three rates of B (0, 0.56, and 1.12 kg/ha), and three rates of Ca (0, 65, and 130 kg as gypsum/ha) were applied under field conditions at three locations.

Under greenhouse conditions, significant interactions between the effects of B and Ca on growth and quality were observed. High Ca levels in the absence of applied B resulted in increased yields, lower seed quality (percent sound mature kernels), and extremely large increases in amounts of internal damage (due to B deficiency). No significant difference in yield response to B and Ca applications were found under field conditions. Peanuts showed a significant B by K interaction. Application of B with rates of potassium resulted in small increases in yield, except at the highest B and K levels where yields were reduced.
The Nitrogen Status Beneath Beef Cattle Feedlots in Eastern Nebraska
Authors: Ellis J. R. , Mielke L. N. , Schuman G. E.
Published: July 2010

Soil cores (129) were taken from 15 eastern Nebraska feedlots in the Elkhorn and Platte river valley areas. The sites represented a wide range of conditions from small farm feedlots to large commercial operations.

Most feedlots did not constitute a nitrate pollution hazard to ground water. Upland feedlots, with slopes >5%, contained less than 10 ppm NO3‐‐N in the ground water; however, slopes <5% had increased frequency of NO3‐‐N in the ground water. Only one river‐valley feedlot ground‐water sample exceeded 10 ppm NO3‐‐N. Problems of ground water with > 10 ppm NO3‐‐N were localized. The feedlot and cropland conditions examined and ranked according to decreasing average NO3‐‐N in the core were: abandoned feedlot > feedlot‐cropland > upland feedlot > corn (Zea mays L.) > river‐valley feedlot > profiles under feedlot mounds > alfalfa (Medicago sativa L.) > grassland.
Fertilizer or Salt Leaching as Affected by Surface Shaping and Placement of Fertilizer and Irrigation Water
Authors: Kemper W. D. , Olsen John , Hodgdon Alan
Published: July 2010

Irrigation in furrows and placement of fertilizer in bands in ridges was evaluated as a means for allowing overirrigation to bypass nitrate and reduce leaching losses. In a loamy sand, placement of band 0 to 5 cm higher than the surface of water in the furrow allowed over 120 cm of overirrigation before the salt began to leave the root zone. In the clay loam a similar delay of nitrate removal was not achieved until the band was 10 cm higher than the water surface. This difference appeared to be associated with a perched water table that developed in the “cultivated” layer of the clay loam soil due to higher hydraulic conductivity in cultivated than in the lower soil.

Downward movement of relatively concentrated salt solution near the band, due to its greater density, was a factor that allowed fertilizer bands at lower levels to enter the mainstream of the leaching water.

Leaching of fertilizer from a soil can be delayed by placing it in ridges and irrigating in furrows rather than broadcasting fertilizer followed by flood irrigation. The practical significance of nitrate staying in the root zone longer as a function of such water and fertilizer management should be tested in the field.
Black Spruce Site Quality as Related to Soil and Other Site Conditions
Authors: Lowry G. L.
Published: July 2010

Site factors were studied in relation to site index in 125 black spruce (Picea mariana Mill. BSP.) stands of eastern Canada. Site index was higher in the Continental than in the Atlantic Region, apparently due to differences in effective solar energy. In both regions site quality was related primarily to soil moisture and nutrients. Site index is better on freely drained, mesic mineral soils. These sites have modest humus accumulations. Soil analyses indicate that nitrogen and phosphorus limit tree growth over a broad range of site conditions. Few of the factors studied appear to have site index prediction value. However, many were suitable for site classification purposes. For extensive mapping of site productivity the primary framework should be landform and associated soils and geologic formations. Within this classification, moisture regime and nutrient regime may be included.
Field and Growth‐Chamber Evaluations of Potassium Polyphosphate
Authors: Armbruster J. A. , Murphy L. S. , Meyer L. J. , Gallagher P. J. , Whitney D. A.
Published: July 2010

Results of field and growth chamber investigations indicate that potassium polyphosphate (KPP) is as effective as ammonium orthophosphate (AOP), ammonium polyphosphate (APP), and triple superphosphate (TSP) as a P source for corn (Zea mays L.) and grain sorghum (Sorghum bicolor L.). At one field site, on a soil high in total Fe, low P availability early in the growing season from both KPP and APP limited crop response. Field investigations of banded applications of KPP and AOP in direct contact with wheat (Triticum aestivum L.) and grain sorphum seed had little effect on seedling emergence. In a growth chamber, however, a high P rate as banded AOP retarded dry‐matter yield of grain sorghum. Application of large amounts of P as KPP, AOP, APP and TSP to corn in the presence of low available Zn significantly reduced Zn concentrations in the plants but there was no significant difference in the effects of the various P carriers.