bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Mulch Effects on Seedbed Temperature and Water During Fallow in Eastern Washington
Authors: Papendick R. I. , Lindstrom M. J. , Cochran V. L.
Published: July 2010

Depth of dry soil mulch affected summer soil temperatures and seed‐bed water at the end of fallow in the dryland wheat region of eastern Washington. Increasing the depth of the tillage mulch from 6 to 11 cm reduced summertime seed zone drying sufficiently to benefit wheat emergence. Reduction of drying was greatest when the seed zone had good capillary continuity with the deeper soil layers. Drying depth and intensity was greater with a cloddy soil mulch than with a fine mulch.

The seed zone water‐conserving effect of a fine soil mulch was related to the lowered temperatures and temperature gradients across the seed zone associated with the increased mulch depth. The deeper soil mulch conserved seedbed water through increased resistance to water flow from moist layers to the atmosphere, and through increased thermal insulation of the moist soil below the dry mulch. Surface‐applied straw (4,000 kg/ha) decreased seed‐zone temperatures under the shallow mulch only.

The key factor in conserving seedbed water through extended periods of hot, dry weather is that the loss rates from the seed zone be balanced by upward unsaturated flow from deeper layers. As the soil dries, the relative importance of loss rates through evaporative loss across the dry layer and thermally induced flow downward increases because of decreasing return flow from the deeper layers along matric potential gradients. Under these dryland conditions, it appears that seedbed water could be best conserved through using a soil mulch of maximum resistance to vapor and liquid water flow, and maximum thermal insulation, overlying a seed zone having good capillary continuity with the deeper soil layers. The stratification produced by moderately deep rod‐weeding appears to provide such a mulch.
Encasing Undisturbed Soil Cores in Plastic
Authors: Mielke Lloyd N.
Published: July 2010

A technique was developed using a 10.2‐cm‐diameter soil sampler to obtain undisturbed soil cores encased in heat‐shrinkable tubes. Six cores were taken in feedlots, five from sandy loam, and one from a silty clay loam. The undisturbed soil core is placed inside the plastic tube during the sampling operation, thereby minimizing core handling and possible fracture.
Nature of Phosphorus Retention and Adsorption with Depth in Soil Columns
Authors: Logan T. J. , McLean E. O.
Published: July 2010

Sequential fractionation of adsorbed 32P and changes in equilibrium P concentration (EPC) with depth were studied in a column leaching experiment. In general, the percentage of NH4Cl‐extractable P decreased rapidly with depth; the percentage of NH4F‐extractable P decreased rapidly in the initial 2‐cm depth and then remained fairly constant. Percentage NaOH‐extractable P increased as that of NH4F‐extractable P decreased, and that of H2SO4‐extractable P increased gradually with depth.

Equilibrium P concentration (EPC) decreased with depth and increased as rate of P applied increased. These EPC values reflected both depth of penetration of applied P and level of native P in the soil.
Kinetics of Isotope Exchange on Hydroxyapatite
Authors: Kukura M. , Bell L. C. , Posner A. M. , Quirk J. P.
Published: July 2010

The kinetics of exchange of 32P and 45Ca in aqueous solution with synthetic, stoichiometric hydroxyapatitie was followed up to 200 hours. Seventy percent of the total exchange occurred in 1 hour, and isotopic equilibrium was reached at approximately 40 hours. Using McKay (13) plots, the exchange reaction was shown to be heterogeneous. Diffusion of isotope through solution “compartments” was considered to be rapid in relation to exchange occurring at the solid surface. The nature of the exchange curve was explained by the differing energies of activation of exchange for surface atoms located at different positions on the crystal landscape. The use of well‐crystallized, stoichiometric hydroxyapatite resulted in the establishment of a well‐defined isotopic equilibrium (11) with little evidence of loss of isotope through intracrystalline diffusion or recrystallization.
Diffusion of Zinc in Soils as a Function of Applied Zinc, Phosphorus, and Soil pH
Authors: Melton James R. , Mahtab Samuel K. , Swoboda Allen R.
Published: July 2010

Self‐diffusion coefficients, D, of 65Zn were determined in two Texas soils. In the Norwood loam, a calcareous soil of pH 8.2, the effect of applied P and Zn on diffusion coefficients was studied. As the applied P was raised from 0 to 240 ppm, the D value obtained at 0 ppm Zn decreased significantly from 11.73 × 10‐11 to 8.57 × 10‐11 cm2/sec; at 40 ppm Zn, the D value decreased significantly from 28.51 × 10‐11 to 16.33 × 10‐11 cm2/sec. Zinc diffusion doubled as the applied Zn was increased from 0 to 40 ppm at all levels of applied P. In the Nacogdoches sandy loam, a soil initially of pH 6 but subsequently raised to pH 7.2 and 7.9 by liming, there was little difference between the D values obtained at pH 7.2 and 7.9. When the applied Zn was increased from 0 to 20 ppm, the D value increased from 5.35 × 10‐11 to 7.83 × 10‐11 cm2/sec at pH 7.2 and from 3.97 × 10‐11 to 6.26 × 10‐11 cm2/sec at pH 7.9. However, D values obtained at pH 6 were much larger than those obtained at pH 7.2 and 7.9. As the Zn level was raised from 0 to 20 ppm at pH 6, the D value increased from 19.90 × 10‐11 to 19.53 × 10‐9 cm2/sec. It appears from this study that the effect of Zn and pH on diffusion of Zn is greater than that of applied P.
Impact of Earthworm Introduction on Litter Burial and Nutrient Distribution in Ohio Strip‐Mine Spoil Banks
Authors: Vimmerstedt John P. , Finney James H.
Published: July 2010

Earthworms (Lumbricus terrestris L.) actively buried leaf litter and humus, and deposited castings on the surface of an acid (pH 3.5–4.0) shale spoil bank revegetated with black locust (Robinia pseudoacacia L.). Earthworms persisted for 5 years in the coal spoils and buried or consumed the equivalent of 5 metric tons of leaf litter/ha. In a greenhouse study, earth‐worms in cores of spoil from the mined area buried or consumed a 60‐mm thick layer of litter and humus in 174 days. The equivalent of 9.5 metric tons of litter and 52.5 metric tons of humus was buried or consumed/ha, while the equivalent of 16.7 metric tons of castings was deposited on the surface. Exchangeable cations and available P in the mineral spoils increased as follows: K from 0.17 to 0.19, Ca from 1.7 to 2.7, and Mg from 1.8 to 2.5 meq/100 g of spoil; and available P increased from 1.7 to 4.2 ppm. Earthworm activity did not influence growth of northern red oak (Quercus rubra L.) seedlings planted in the cores.

In another study, 10 Lumbricus terrestris were introduced on a calcareous strip‐mine spoil revegetated with European alder (Alnus glutinosa L.). In 5 years, the earthworm population increased to a density of 60 middens/m2 over an area of 700 m2.

Clearly, earthworms can be established on revegetated coal spoil banks, where they promote incorporation of organic matter into the mineral spoil.
Inhibition of Nitrification in Soils
Authors: Bundy L. G. , Bremner J. M.
Published: July 2010

The effectiveness of 24 compounds proposed as inhibitors of nitrification in soils was studied by determining the effects of 10 ppm (soil basis) of each compound on the amounts of nitrate and nitrite produced when soils treated with ammonium sulfate (200 ppm of ammonium N) were incubated at 30C for 14 days. With the soils used, the average effectiveness of the most potent inhibitors decreased in the order: 2‐chloro‐6‐(trichloromethyl)‐pyridine (N‐Serve) > 4‐amino‐1,2,4‐triazole (ATC) > sodium or potassium azide > 2,4‐diamino‐6‐trichloromethyl‐s‐triazine (CL 1580) > dicyandiamide > 3‐chloroacetanilide > 1‐amidino‐2‐thiourea > 2,5‐dichloroaniline > phenylmercuric acetate > 3‐mercapto‐1,2,4‐triazole or 2‐amino‐4‐chloro‐6‐methyl‐pyrimidine (AM) > sulfathiazole (ST) > sodium diethyldithiocarbamate. The other compounds tested (gallic acid, cysteine, cystine, methionine, methionine sulfoxide, methionine sulfone, ethionine, thiourea, 1‐allyl‐2‐thiourea, and 2‐mercapto‐benzothiazole) had little or no effect on nitrification of ammonium in soils under the conditions studied.

The effectiveness of the inhibitors studied was markedly affected by soil type, soil temperature, and substitution of urea for ammonium sulfate as the source of nitrifiable nitrogen. Most of the inhibitors were considerably more effective at 15C than at 30 C.
Phosphorus Losses from Four Agricultural Watersheds on Missouri Valley Loess
Authors: Schuman G. E. , Spomer R. G. , Piest R. F.
Published: July 2010

Phosphorus losses from four field‐size experimental watersheds at Treynor, Iowa, were measured during 1969, 1970, and 1971. A contour‐planted corn watershed and a pasture watershed were fertilized at the recommended P rate (39 kg/ha). A level‐terraced and a second contour‐planted corn watershed were fertilized at 2.5 times this rate. At the high level of P fertilization, phosphorus loss by surface runoff from the contour‐planted corn watershed was 0.495 kg/ha in 1969, 1.034 kg/ha in 1970, and 2.130 kg/ha in 1971. Level terraces greatly reduced P loss by reducing runoff and erosion.

Water samples for all runoff events taken above the overfall of each watershed gully contained considerably more inorganic P in solution than samples taken at the weir site, 70 to 230 m downstream. This reduction in solution P was caused by the adsorption of P by the additional suspended soil material entering the stream from gully erosion.
Automated Repetitive Short‐Term Extraction of Soil Samples
Authors: Ballaux Jean‐Claude , Peaslee D. E.
Published: July 2010

Studies of P release during short contact times between soil and extractant were conducted on soils with an automatic sequential extracting apparatus. Varying contact times between the soil and extracting solution can be set by an adjustable multigang timer of 20‐min cycle. Data for two soils of different textures show marked differences in P extraction. The apparatus appears adaptable for evaluating short‐term release of other ions and pesticides from soils.
Automated Total Nitrogen Analysis of Soil and Plant Samples
Authors: Schuman G. E. , Stanley M. A. , Knudsen D.
Published: July 2010

Soils research dealing with environmental quality requires the analysis of large numbers of samples to better characterize the problem. An automated technique, using a Tecator digester and Technicon AutoAnalyzer, has proved to be as reliable as the standard micro‐Kjeldahl procedure and permits more rapid analysis of the digests (30 per hour). The system is compact and involves fewer steps for analytical error.
A Mathematical Investigation of Steady Infiltration from Line Sources
Authors: Zachmann David W. , Thomas Adrian W.
Published: July 2010

The objective of this study is to develop equations which can be used in the design of subsurface irrigation systems. This first paper deals with the physics of steady infiltration from a distribution of line sources which lie in a horizontal plane and are parallel and equally spaced. The analytical solution describes the flow from the line sources in the presence of uniform infiltration or evaporation at the soil surface. To increase the utility of the solution, the equations for matric flux potential and stream function are written in dimensionless form.
Response of Salinity Sensors to Rapidly Changing Salinity
Authors: Wesseling J. , Oster J. D.
Published: July 2010

Based on the assumption that diffusion of solutes into and out of the sensitive element of a salinity sensor determines its response time, a theory was developed to describe the response of the sensor to changes in soil salinity. This theory was experimentally verified in solution and in soils. The response of a sensor was shown to be adequately described by a single response factor. Proper use of this factor permits the actual electrical conductivity of the soil solution to be inferred from sensor readings where soil salinity changes rapidly.
Land Sale Prices in South Dakota and Their Relationship to Some Soil, Climatic, and Productivity Factors
Authors: Westin F. C. , Stout M. , Bannister D. L. , Frazee C. J.
Published: July 2010

About 2,700 land sale figures were used along with individual county soil‐association maps to determine average peracre values of South Dakota counties. Annual average precipitation and temperature data were connected to landsale figures using multiple‐regression equations. County crop productivity also was related to precipitation and county land sale data. The best prediction formula for explaining average county land values was a fifth‐order polynomial‐regression with precipitation as the variable. This explained 95% of the variance. Most of the variance (84%) of county cropland productivity was explained with a second‐order polynomial‐regression having annual‐average precipitation as the variable, and 86% of the variance of county land value figures was explained with a second‐order polynomial‐regression having county cropland productivity as the variable. However, only a little over 54% of the variance of individual farm sales could be explained using regression equations involving climate, slope, and soil‐texture as variables.
Scanning Electron Microscopy of Opaque Opaline Forms Isolated from Forest Soils in Ohio
Authors: Wilding L. P. , Drees L. R.
Published: July 2010

Opaque opal bodies isolated from surface horizons (A1) of three Miamian soils were examined with correlative light optical and scanning electron microscope techniques. Opaque bodies comprise from 15 to 70% of the opal isolated from these horizons and range in morphology from spheres to nondescript equidimensional, rod, or elongated forms. Under transmitted light only the gross morphological outline can be deduced. However, with the scanning electron microscope a strong similarity exists between many of the opaque bodies and spheres, cups, mosaic aggregates, and bladed opaline forms isolated from reference deciduous tree leaves. Some of the opaque forms provide positive differentiation of grass vs. forest origin of the opal.
Determining the Acid‐Titratable Basicity of Calcareous Soils
Authors: Miyamoto Seiichi , Bohn Hinrich L. , Renthal James
Published: July 2010

The measured value of acid‐titratable basicity (ATB) or “alkaline earth carbonate from acid neutralization” decreases with increasing soil/solution ratio or the increasing concentration, C, of excess acid. The ATB is almost independent of C, however, in the range of 0.1 to 0.3N acid remaining after neutralization with 0.5N HCl. In coarse‐textured soils, the ATB extrapolated to C = 0 is reasonably close to the soil's carbonate content.
Sulfate Reduction and Sulfide Oxidation in Flooded Soil as Affected by Chemical Oxidants
Authors: Engler R. M. , Patrick W. H.
Published: July 2010

The effect of various chemical oxidants on inhibition of sulfide (S2‐) in a previously reduced soil was studied. Oxygen, KNO3, MnO2, ferricitrophosphate, and FePO4 · 2H2O at rates equivalent to 1,000 ppm O2 (O2 added at rates of either 300 or 500 ppm) were both added prior to flooding and after soil reduction had reached a maximum. The results indicate that the more soluble oxidants had the greatest effects in maintaining more positive redox potentials and in delaying sulfate (SO42‐) reduction to S2‐. The soluble oxidants (KNO3 and ferricitrophosphate) delayed S2‐ production by 17 and 9 days, respectively. The less soluble compounds (MnO2 and FePO4 · 2H2O) were less effective in delaying S2‐ production but persisted longer in preventing maximum S2‐ buildup.

Adding the oxidants after maximum S2‐ accumulation showed the most pronounced effect on S2‐ oxidation from KNO3 and the least effect from MnO2. Oxygen at the rate of 500 ppm was also a very effective oxidant. Sulfate reduction to S2‐ and S2‐ oxidation were apparently controlled by, or at best related to the redox potential since SO42‐ reduction and S2‐ oxidation both appeared to commence at potentials in the vicinity of −100 mV.
Detection of Carbonyl Sulfide and Other Gases Emanating from Beef Cattle Manure
Authors: Elliott L. F. , Travis T. A.
Published: July 2010

Carbonyl sulfide (COS) was detected in the headspace above anaerobic columns of fresh manure and feedlot compost. One‐tenth ng S/ml of the compound was detected in gases from a debris basin and soil profile of a feedlot also. Carbonyl sulfide has not been reported from these sources previously.

During the first 24 hours of anaerobic incubation, COS appeared above the manure. The concentration exceeded 8 ng S/ml the second day and began to decline after 5 days. Hydrogen sulfide followed a similar pattern except that it persisted for 16 days. Only traces of COS were found above some of the replications of the anaerobically incubated compost. Hydrogen sulfide appeared above the compost after 5 days and persisted throughout the 37‐day incubation. Methane appeared more quickly above the manure than above the compost. However, CH4 never exceeded 7.5% above the manure whereas it exceeded 36% above the compost.
Salt Tolerance of Mexican Wheat: I. Effect of NO3 and NaCl on Mineral Nutrition, Growth, and Grain Production of Four Wheats
Authors: B. Carlos Torres , Bingham F. T.
Published: July 2010

Wheat plants (Triticum aestivum) were grown to full maturity under sand culture conditions with variable levels of substrate NO3 and NaCl. Leaf samples were collected at early spike emergence for chemical analysis of Ca, Mg, Na, K, P, Cl, NO3, and total N. Growth measurements included those of flag leaf length, tiller and spike formation, and total straw and grain.

The slower maturing variety, Cajeme 71, grew much more vigorously than the more rapidly maturing varieties Inia 66, Yecora, and Siete Cerros. The salt tolerance of Cajeme 71 was 2‐ to 4‐fold greater than that of the other varieties tested.

Leaf NO3 of samples collected at early spike emergence correlated with grain yields irrespective of substrate NaCl levels, suggesting that the growth retardation associated with excessive substrate NaCl was due in part to a Cl‐induced NO3 deficiency.
Radiocarbon Chronology and Problems in Its Interpretation for Quaternary Loess Deposits—South Canterbury, New Zealand
Authors: Runge E. C. A. , Goh K. M. , Rafter T. A.
Published: July 2010

The sequence of events for the loess deposits on the Timaru Downs as indicated by 14C dating of clay‐organic complexes, and whole and fractionated peat deposits is as follows: present soil and surficial peat have been forming from present to 9,900 years BP; uppermost loess was deposited between 9,900 and 11,800 years BP; first palesol and buried peat was formed 11,800 to 31,000 or more years BP; and the second loess was deposited > 31,000 years BP.

The mean residence time (MRT) of clay‐organic complexes from the B2 horizon of the modern soil and paleosols was compared to the MRT's of fractionated and unfractionated samples of organic material from stratigraphically related peat deposits. In this study the chronology from whole organic samples was improved by dating fulvic acid, humic acid, and residence (humin) fractions. Humic acid fractions gave consistently older dates than residue fractions. The relative amount of these three fractions provides information about subsequent contamination. Concentrated organic deposits are preferred. However, clay‐organic complexes of paleosols can be used to approximate the chronology of events after a correction for age at time of burial if contamination by organic material through leaching during subsequent soil development can be accounted for. The clay‐organic complex method may extend 14C dating to paleosol horizons enriched with clay (B2 horizons) but devoid of organic enriched horizons (peat, muck, or A horizons).
Performance of Sulfur‐Coated Urea Under Intermittently Flooded Rice Culture in Peru
Authors: Sanchez P. A. , O. A. Gavidia , Ramirez G. E. , Vergara R. , Minguillo F.
Published: July 2010

Short‐statured, high yielding rice (Oryza sativa L.) varieties grown extensively in northern Peru require extremely high rates of conventional N sources to achieve maximum yields. The recovery of applied N is extremely low due to the use of intermittent flooding. This water management system results in heavy N losses even with properly timed split applications. In search of simpler and more efficient methods of N management, eight field experiments were conducted in the region to evaluate sulfur‐coated urea (SCU), an experimental, slow‐release N sources supplied by the Tennessee Valley Authority. Rice yields were increased an average of 59% more by pretransplant‐incorporated SCU than by urea or ammonium sulfate applied in the same manner. SCU produced an average of 20% higher grain yield response than topdressed applications of urea or ammonium sulfate. SCU applications increased panicle production, N uptake at harvest, and the apparent recovery of added N. Beneficial effects of SCU were more pronounced in sites where check yields were low, especially less than about 4.8 ton/ha. In sites with high N supplying capacity, SCU produced excessive vegetative growth which resulted in yield reductions at high N rates.

Regardless of an assumed 48%‐higher unit N cost in SCU, the overall benefits of pretransplant‐incorporated applications of SCU were favorable since there was a decrease of 40% in the optimum rate of N and the need for precise timing of application was eliminated.
Determination of Equivalent Radii for Rectangular Drains
Authors: Warrick A. W.
Published: July 2010

A relationship is developed giving the circular drain size which is equivalent to a rectangular drain. A rectangular drain may result when a highly permeable envelope of rectangular cross‐section is used around a buried drainage tube. A plot of re/ √ ab is given as a function of a/b with re as the circulat drain radius and a and b the semi‐width and semi‐height of the rectangular drain. The minimum value of re/ √ ab is 1.18 and corresponds to a square (which is the case considered by Kirkham and Selim, 1973). The equivalent radius is useful in adapting drainage formulas giving spacings, depth, etc., to rectangular drains.
Calcium‐Magnesium‐Potassium Equilibria in Some California Soils
Authors: Carlson R. M. , Buchanan J. R.
Published: July 2010

Ion exchange equilibria in several soils were studied to seek equilibrium equations that could be used in chromatographic models dealing with movement and distribution of fertilizer potassium in soil profiles. Soil samples were equilibrated with mixtures of CaCl2, MgCl2, and KCl solutions and then extracted with NH4OAc to determine exchangeable cation compositions at equilibrium. It was necessary to correct the exchangeable cation concentrations by subtracting the cations extracted from nonexchangeable sources by NH4OAc. Vanselow's, Davis', Gapon's, or Kerr's equations would not describe the equilibria. Empirical equations of the form:
urn:x-wiley:03615995:saj2sssaj197303615995003700060019x:equation:saj2sssaj197303615995003700060019x-math-0001 and
urn:x-wiley:03615995:saj2sssaj197303615995003700060019x:equation:saj2sssaj197303615995003700060019x-math-0002 did describe the equilibria with all three cations present, and over a wide range of composition, for all soils studied. In these equations Ai is the solution ion activity, k is the distribution coefficient, Ei is the equivalent fraction of the exchangeable cation, and Di and Pi are arbitrary constants that are characteristic for each soil and each cation.
Ammonia Volatilization from Surface Applications of Ammonium Compounds on Calcareous Soils: I. General Theory
Authors: Fenn L. B. , Kissel D. E.
Published: July 2010

Volatilization of NH3 from NH4‐‐N salts applied to the surface of a calcareous soil was investigated. Ammonia losses from surface applied NH4F, (NH4)2SO4, and (NH4)2HPO4 were 68, 54, and 51%, respectively, of the added NH4‐‐N in 100 hours. Ammonium nitrate, NH4Cl, and NH4I lost 18, 18, and 16%, respectively, of the added NH4‐N in 100 hours. An increase in pH at the soil surface resulted in higher loss of NH3. Applications of 550 kg N/ha as NH4F and (NH4)2SO4 increased the pH from 7.6 to 8.9 and 8.1, although pH decreased rapidly with time. Soil pH decreased to 6.8 by the addition of 550 kg NH4‐N/ha as NH4NO3 and changed very little in 50 hours.

Ammonium sulfate applied to soils saturated with Mg2+ and Ba2+ gave similar results. Solubility of the apparent reaction product was the major factor regulating NH3 volatilization. Formation of a Ca2+ reaction product, such as CaSO4, tends to drive the reaction to the right and favors formation of (NH4)2CO3. A proposed mechanism of the observed loss of NH3 is as follows: when an ammonium salt dissolves in a calcareous soil, (NH4)2CO3 and a Ca2+ salt of varying solubility forms. Ammonium carbonate subsequently decomposes, losing CO2 at a faster rate than NH3. This causes formation of NH4OH and an increase in pH and greater NH3 losses.
Chemical and Spectroscopic Methods for Assessing Subsidence in Florida Histosols
Authors: Volk B. G. , Schnitzer M.
Published: July 2010

The extent of subsidence of cultivated histosols in the Everglades of southern Florida can be assessed by chemical and spectroscopic methods. Higher subsidence rates tend to be associated with the following changes in the chemistry of humic acids, the principal constituent of histosols: (i) increases in CO2H, phenolic OH, quinone, and ketonic C=O groups; (ii) decreases in aliphatic structures as shown by IR spectra and alcoholic OH groups; and (iii) decreases in molecular complexity as indicated by E4/E6 ratios and possibly by free radical measurements.

The chemical reactions involved appear to be mainly oxidative, leading at first to the degradation of aliphatic structures to C=O and CO2H groups, and finally to attacking the more stable aromatic structures with degradation to CO2 and H2O.

Functional group analysis and measurements of E4/E6 ratios are useful and experimentally simple methods for estimating the degree of degradation of Florida histosols.
Effects of Chelated and Nonchelated Cobalt and Copper on Yields and Microelement Composition of Bush Beans Grown on Calcareous Soil in a Glasshouse
Authors: Wallace A. , Mueller R. T.
Published: July 2010

Several levels of chelated [EDTA (ethylene diaminetetraacetate)] and nonchelated Co and Cu were applied to bush beans (Phaseolus vulgaris L. var. ‘Improved Tendergreen’) grown in a glasshouse in calcareous Hacienda loam soil. Objectives of the study were to determine if chelated Co and Cu were more available in the calcareous soil than were inorganic sources, and if chelating agents contribute to toxicities at relatively high levels of Co and Cu. CoEDTA and CuEDTA applications caused higher levels of Co and Cu, respectively, in the plants than did inorganic sulfate sources. The applications of both metal chelates caused slight depressions in yields of dry matter at 50 ppm metal added and CoEDTA behaved similarly at 25 ppm Co. Each metal chelate was associated with a decreased Fe concentration in leaves at the highest application level. The Co in leaves was similar for applications of 50 ppm Co as CoSO4 and 2.5 ppm Co as CoEDTA. The Cu concentration in leaves was greater for an application of 5 ppm Cu as CuEDTA than for 25 or 50 ppm Cu as CuSO4.
Water‐Sediment Splitter for Runoff Samples Containing Coarse‐Grained Sediment
Authors: Fleming Walter G. , Leonard Ralph A.
Published: July 2010

A water‐sediment sample splitter was designed and constructed for dividing samples up to 20 liters into three equal and representative smaller samples for chemical and physical analyses. This funnel‐shaped device with a mechanical agitator divides samples containing particles up to 2 mm without first separating the sediment from the water. Evaluation showed that the splitter divided samples containing coarse sediments into three parts with a distribution of 33% ± 2% in each. The device has application in assuring representative samples of runoff from watershed or similar runoff studies.
Flux‐Gradient Relationships and Soil‐Water Diffusivity from Curves of Water Content versus Time
Authors: Nofziger D. L. , Ahuja L. R. , Swartzendruber D.
Published: July 2010

Direct analysis of a family of curves of soil‐water content versus time at different fixed positions enables assessment of the flux‐gradient relationship prior to the calculation of soilwater diffusivity. The method is evaluated on both smooth and random‐error data generated from the solution of the horizontal soil‐water intake problem with a known diffusivity function. Interpolation, differentiation, and integration are carried out by least‐squares curve fitting based on the two recently developed techniques of parabolic splines and sliding parabolas, with all computations performed by computer. Results are excellent for both smooth and random‐error input data, whether in terms of recovering the original known diffusivity function, assessing the nature of the flux‐gradient relationship, or in making the numerous checks and validations at various intermediate stages of computation. The method applies for any horizontal soil‐wetting process independently of the specific boundary conditions, including water entry through a nonzero inlet resistance. It should be adaptable to horizontal dewatering, and extendable to vertical flow.
Properties of Some Soils of the Upper Amazon Basin of Peru
Authors: Sanchez P. A. , Buol S. W.
Published: July 2010

Several representative soil profiles of the Peruvian Amazon jungle were collected in the vicinity of Yurimaguas and Iquitos and characterized in the laboratory in order to classify them according to the US soil taxonomic system. The most extensive well‐drained soils are Typic Paleudults; the poorly‐drained ones are Typic Tropaqualfs or Tropaquepts. The Paleudults were predominantly of kaolinitic mineralogy with small quantities of 2:1 minerals present. The poorly‐drained soils were predominantly montmorillonitic or of mixed mineralogy. Where coarsetextured parent materials occur in localized areas. Tropaquods and Haplorthods are found. High base status Haplaquolls are found along the margins of the Amazon and Napo Rivers. The base status of the Paleudults is not as low as in the main soils of the South American savannas. The base status of the more poorly‐drained soils is higher. Evidence from surrounding countries suggests that these soils are very extensive in the Upper Amazon Basin of South America, outside the influence of the Brazilian and Guyana shields. These areas have been previously mapped as Oxisols or their equivalents.
Straw Buildup in Soil with Stubble Mulch Fallow in the Semiarid Great Plains
Authors: Greb B. W. , Black A. L. , Smika D. E.
Published: July 2010

The quantity of wheat (Triticum aestivum L.) straw in the 0 to 7.6 cm depth of soil in wheat‐fallow rotations was determined at Sidney, Montana, Akron, Colorado, North Platte, Nebraska, and Bushland, Texas. Rotation treatments varied between locations but included straw rates, dates of primary tillage, and straw burial times. Types of primary tillage were also studied with continuous wheat at Bushland, Texas.

Quantities of straw found mixed in the surface 7.6 cm of soil at the four Great Plains locations ranged from 1,300 to 7,480 kg/ha. The straw quantities found are influenced by duration of wheat‐fallow rotation, date, and type of primary tillage and straw burial time but were not proportional to the rates of straw mulch used at the beginning of fallow. In a long‐term study plots at Bushland, Texas, straw build‐up was significantly greater with continuous wheat than with wheatfallow. Adding nitrogen fertilizer even at high rates did not influence the amount of straw found in soil at Sidney, Montana or North Platte, Nebraska.
Land Response Units — An Aid to Forest Land Management
Authors: Leven A. A. , Meurisse R. T. , Carleton J. O. , Williams J. A.
Published: July 2010

Land Response Units offer a means of grouping broad areas of land that have similar capabilities to produce biomass, and have similar sensitivities to man's uses. The capability of the land to produce flora and fauna is estimated by evaluating the soil ecofactors that sustain the environment, i.e., moisture, temperature, and nutrients. Moisture and temperature factors can be evaluated by classifying the soils using the Soil Taxonomy of the National Cooperative Soil Survey. Soil moisture regimes indicate plant available moisture, and soil temperature regimes indicate temperature conditions for plant growth. Nutrient regimes can be estimated by evaluating soil depth, color, texture, and pH. Sensitivity to man's uses is estimated by evaluating the erosion hazard, runoff potential, and slope gradient of the land. These three factors are used to estimate the ability of the land to accept man's activities without serious loss of productivity or stability.

The Land Response Unit concept is adaptable for use on intensively managed agricultural lands as well as less intensively managed lands.
Anion Exclusion and Coupling Effects in Nonsteady Transport Through Unsaturated Soils: II. Laboratory and Numerical Experiments
Authors: Bresler E. , Laufer A.
Published: July 2010

A numerical model for the simultaneous transport of anions and water as developed in Part I of this work was compared with measured chloride and water flow data. Laboratory soil‐column experiments were conducted under conditions of infiltration, redistribution, and evaporation of water in the upper part of the soil profile. The effects of convection, ionic diffusion, mechanical dispersion, anion exclusion, and water flow in response to salt concentration gradients on the comparison between numerical and measured data were considered jointly. The agreement between theory and experiment, as expressed by flow into and out of the soil column and by water content and salt distribution profiles, was generally good. The results were relatively insensitive to anion exclusion and osmotic effects. Estimates of dispersivity as obtained from miscible displacement experiments were found to be sufficient for prediction purposes. The numerical as well as the laboratory data indicate that for the conditions studied, osmotic gradients and anion exclusion effects are of minor importance.
Packing‐Induced Radial Particle‐Size Segregation: Influence on Hydrodynamic Dispersion and Water Transfer Measurements
Authors: Ripple C. D. , James R. V. , Rubin Jacob
Published: July 2010

Previous laboratory studies have shown that radial particlesize segregation occurs when soil columns are prepared with the aid of vibratory compaction. This segregation is characterized by a greater proportion of coarser particles near the periphery than in the central region of the column. A specially devised, alternative repacking technique, utilizing a vibration‐free impacting apparatus, reduced such segregation in soil columns to an acceptably low level. Soil columns prepared by the above two packing procedures (i.e., with or without induced radial segregation) exhibited significant differences in their water flow and salt transport properties. Miscible displacement tests exhibited effluent‐concentration histories that agree with currently accepted one‐dimensional dispersion theory in the case of nonsegregated soil columns. On the other hand the results from segregated soil columns could not be reconciled with this theory. Horizontal infiltration into either segregated or nonsegregated soil columns produced significantly different moisture content profiles. However, it yielded rather similar relations between infiltration volume and the square root of time.
Phosphorus Retention in Coastal Plain Forest Soils: I. Relationship to Soil Properties
Authors: Ballard R. , Fiskell J. G. A.
Published: July 2010

Phosphorus‐retention capacities in the surface horizons of 42 forest soils of the US Southeastern Coastal Plain were determined from the adsorption maximum of the Langmuir isotherm and by saturation with 2,500 µg P/g soil. Both indices were closely correlated (r = 0.986) although on the average the saturation method gave retention capacities two to three times greater than those derived from the Langmuir equation. Range in retention capacities were from 0 to 1,288 µg P/g soil from the concentrated solution. Spodosols generally had the lowest retention capacities although there was considerable overlap between soil orders.

Several soil properties (% clay, % silt, pH, loss on ignition) were significantly correlated with P retention but partial correlation analysis showed that, except for pH and to a lesser extent clay, the relationship was indirect through association with extractable Al. Extractable Al and Fe provided the best indices of P retention. The most successful of the extractants of Al for predicting P retention (r = 0.934) was 1N NH4OAc (pH 4.8), while 0.3M (NH4)2C2O4 (pH 3.2) was the most successful of the extractants of Fe (r = 0.903) for predicting P retention.

Multiple regression analysis of P retention on exchangeable, amorphous, and crystalline forms of Al and Fe showed that on a per unit weight basis, the order of activity in P retention was exchangeable > amorphous > crystalline with apparently little distinction between Al and Fe within these categories. The greater contribution of Al than Fe to P retention in these soils was primarily a function of the greater amount of Al than Fe in the active forms.
Biodegradation of Nitrilotriacetate (NTA) in Soils
Authors: Tiedje J. M. , Mason B. B.
Published: July 2010

Nitrilotriacetate (NTA) was biodegraded in a variety of soils as measured by total CO2 and 14CO2 production from 14C‐carboxyl‐NTA. Production of CO2 and 14CO2 followed similar patterns and suggested complete degradation of NTA; 14CO2 production was used routinely to assay NTA dissimilation. At 40 ppm of NTA in soils receiving sewage effluent and in muck soils, maximum rates of degradation were 8 to 10 ppm/day while in mineral surface soils, they ranged from 0.5 to 6 ppm/day; the rates in subsoils were always less than for the surface soils from the same site. Degradation rates did not correlate with pH, drainage, texture, or plant cover. Rates of degradation increased from 2 to 64 ppm/day as NTA concentration was increased from 10 to 600 ppm. 14CO2 production from NTA did not occur anaerobically and was severely limited under microaerophilic conditions. NTA was degraded at 24 and 12.5C; it was also degraded at 2C if previously acclimatized at 12.5C. Iminodiacetate was a possible intermediate in NTA degradation while N‐methyliminodiacetate was not.
Differential Response of Two Maize Inbreds to Molybdenum Stress
Authors: Brown J. C. , Clark R. B.
Published: July 2010

This study was done to determine why Pa36 maize failed to grow and WH maize grew well on acid Bladen soil. The soil is known to be relatively high in Al which often interferes with P uptake and utilization by plants. We were surprised that Pa36 grew so poorly because Pa36 utilized P more efficiently than WH when the two inbreds were subjected to P stress associated with Al toxicity in nutrient solutions.

The slight chlorosis and twisting of Pa36 leaves looked very much like cooper deficiency symptoms in barley and wheat, but adding copper to the soil did not correct the symptoms.

Spectographic analysis of the plant material showed that Mo concentrations in Pa36 leaves were lower than in those of WH. Adding Mo to the soil corrected the deficiency. The Modeficient Pa36 contained higher concentrations of nitrate than WH, but the nitrate contents of Mo‐sufficient Pa36 and WH were approximately equal.

The Mo in the seed could not account for the difference in growth and Mo content of the two inbreds. We conclude that WH has the ability to take up more Mo than Pa36 from the acid Bladen soil.
Effects of Calcium Carbonate on the Availability of Nutrients in an Acid Soil
Authors: Helyar K. R. , Anderson A. J.
Published: July 2010

The four pasture species alfalfa (Medicago sativa L.), subterranean clover (Trifolium subterraneum L.), Harding grass (Phalaris tuberosa L.), and perennial ryegrass (Lolium perenne L.) were grown in pots on an acid sandy loam soil treated with CaCO3 and H2SO4 to give a pH (0.01M CaCl2) range from 4.0 to 5.0.

Calcium carbonate application increased exchangeable calcium and decreased exchangeable aluminum and manganese but had little effect on the exchangeable levels of other cations. All soil solution cations except calcium decreased in concentration with CaCO3 application. These trends are explained in terms of effects of CaCO3 on the exchange equilibria through effects on the exchangeable levels of calcium and aluminum and on the cation exchange capacity. Soil solution sulfate levels were increased by liming while phosphate and nitrate levels were decreased.

Effects of H2SO4 and CaCO3 on plant growth were explained as effects of aluminum toxicity at low pH and phosphorus deficiency at higher pH values. Nutrient concentrations in the plants generally followed the trends in the soil solutions. Some inconsistencies were interpreted as effects of aluminum toxicity.
Sulfur and Manganese Release from Soils Treated with Prilled Sulfur and Sulfur‐Bentonite
Authors: Lindell D. L. , Sornsen R. C.
Published: July 2010

Seven Nebraska soils were used to compare prilled sulfur and a sulfur‐bentonite formulation in regard to the amount of sulfate‐sulfur, manganese, and hydrogen released to a leaching solution after successive incubations. Also the effects of sulfur fertilizer granule concentrations in the soil were studied. Generally, the amount of sulfate‐sulfur and manganese and the pH values in leachates from the columns containing sulfur‐bentonite were not different from those from columns containing prilled sulfur. Differences among soils could not be explained on the basis of measured soil properties. The relationships between the amounts of sulfate‐sulfur or manganese released and percentage sulfur or sulfur‐bentonite in the soil were generally quadratic with the maximum release occurring in the range 30 to 60% sulfur. The greatest amount of sulfur released per gram sulfur added occurred at the lowest sulfur to soil ratio studied. (0.1).
On the Interaction of Water and Heat Transport in Frozen and Unfrozen Soils: I. Basic Theory; The Vapor Phase
Authors: Kay B. D. , Groenevelt P. H.
Published: July 2010

A theory is presented for the transport in porous media of water in response to a temperature gradient and the transport of heat in response to a water pressure gradient. These processes are formulated by exploiting the appropriate equation of energy dissipation and the Clapeyron equation. Several general forms of the Clapeyron equation are developed in order to readily find expressions for the transport coefficients of concern. The cause of the coupled flow processes is related to the heat of vaporization, the heat of fusion, and the partial specific heat of wetting of the soil water. The present paper applies the basic theory to the transport processes via the vapor phase. A second paper is concerned with the liquid phase.
Relation Between Nitrate Absorption and Water Transpiration by Corn
Authors: Liao C. F.‐H. , Bartholomew W. V.
Published: July 2010

The relationship between the absorption of NO3‐N by young corn plants (Zea mays L.) and the quantity of water transpired was studied in solution and soil culture. Tracer N (15N) was employed to measure NO3 absorption. Gravimetric methods were used to monitor evapotranspiration. From solution culture, NO3 was absorbed at rates relatively greater than water. From soil culture, NO3 was absorbed at a relative rate close to that of water when the soil was not pretreated. However, when the soil material was wetted and leached of soluble N before planting corn, NO3 was absorbed at a relative rate 1.5 to 2.0 times that of water. In soil situations where water was not being absorbed by plants, NO3‐N likewise was not absorbed. Mass flow and diffusion both were involved in NO3 transport to roots. Prior cultural conditions had a marked influence on active uptake of NO3 presumably through an influence on specific rates of N absorption.
Investigations in an Oxisol‐Ultisol Toposequence in S.Paulo State, Brazil
Authors: Lepsch I. F. , Buol S. W.
Published: July 2010

Four soil profiles were sampled along a 550‐m toposequence traverse in São Paulo State, Brazil and were characterized with physical, chemical, mineralogical, and micromorphological analyses. The soils were classified and hypotheses were developed concerning their genesis based on soil differences observed.

The soil on the upper part of the traverse has an ochric epipedon over an oxic horizon and is classified as clayey, oxidic, isothermic Typic Haplorthox. Slightly downslope organic matter content increases to form a Typic Umbriorthox of the same family. The soil below these two has an argillic horizon over an oxic horizon and is classified as clayey, oxidic, isothermic Orthoxic Palehumult. The soil in the lowest part has an argillic horizon over decomposed shale and is classified as clayey, Kaolinitic, isothermic Typic Paleudult. The main characteristics distinguishing the soils in the lower part of the toposequence from those in the upper part were the increase in depth and eventual loss of the oxic horizon, decrease in gibbsite content, decrease in chlorite/vermiculite intergradient clay minerals, increase in 2:1 clay minerals, decrease in fine clay to coarse clay ratio, increase in fine silt to clay ratios, increase in illuviated clay, and increase in bulk density.

The genesis of these soils appears to be controlled mostly by the age of the geomorphic surfaces and by the nature of the parent material.
A Similarity During Early Stages of Rain Infiltration
Authors: Ahuja L. R. , Romkens M. J. M.
Published: July 2010

A similarity is shown to exist during early stages of rain infiltration into a relatively dry soil in which the diffusivity varies exponentially with the water content. The similarity leads to simple expressions for describing the wet‐front progress and the water‐content change at the soil surface. The wet‐front equation adequately describes the experimental data for four different soils. The approach can be extended to some cases of rainfall when the intensity is time‐dependent, and to infiltration with transient surface sealing.
Time‐Dependent Linearized Infiltration: II. Line Sources
Authors: Lomen D. O. , Warrick A. W.
Published: July 2010

Water flow from line sources is analyzed using a linearized form of the moisture flow equation. Both single and parallel line sources are considered. Results are particularly relevant for high‐frequency irrigation, such as by trickle sources, for which the soil moisture at any particular point varies over a relatively small range. Numerical calculations include lines of constant matric flux potential (or equal moisture content) as a function of time and the time‐dependent response to a cyclic input. Although the results are developed for surface sources, the analysis may easily be extended to buried sources.
Assessing Soil Salinity and Identifying Potential Saline‐Seep Areas with Field Soil Resistance Measurements
Authors: Halvorson A. D. , Rhoades J. D.
Published: July 2010

The recent widespread increase in the occurrence of seep areas high in salinity in the northern Great Plains has increased the need for soil salinity research. The objective of the study was to examine the use of soil conductivity values calculated from resistance measurements obtained with the four‐probe‐Wenner electrode configuration to identify potential saline‐seep areas and estimate soil salinity in the field.

Plots of apparent soil conductivity (ECa) vs inner‐electrode spacing (a) yielded different types of curves for saline‐seep areas, recharge areas, and intermediate areas. Plots of ECa vs a or ECa values alone can be used to identify potential saline‐seep areas. Significant correlations were obtained in May (r = 0.98) and August (r = 0.96) between apparent soil conductivity (ECa) and electrical conductivity of saturation extracts (ECse) showing that four‐probe soil resistance measurements can also be used to estimate soil salinity (ECse) in the field.