bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting Soil Moisture in the Southern Appalachians
Authors: Helvey J. D. , Hewlett J. D. , Douglass J. E. 
Published: July 2010

AbstractSoil moisture was measured for 3.5 years on forested slopes in the mountains of western North Carolina to develop equations for predicting soil moisture content of watersheds. Predictors used were precipitation and easily measured topographic, seasonal, and soil physical factors; among these, sand content and moisture retention at 1‐bar suction were the best predictors of moisture content. Position on slope (height or distance from the stream channel) appeared to be an important factor only in the lower 25% of the slope. The annual cycle of soil moisture in the top 213 cm approximated a sine wave with a maximum during mid‐April and a minimum during mid‐October. As expected, moisture changes in surface layers were correlated best with rainfall weighted toward days immediately preceding observation; changes in deeper layers were better correlated with rainfall during previous weeks. Seasonal changes in soil moisture content at all depths were greatest upslope and least in the lower slope. Equations developed account for about 88% of the variation in soil moisture (standard error approximately 2–3% by volume) and can be used to predict antecedent moisture distribution for hydrologic and other purposes. Results support the “variable source area” concept of streamflow, but even with the neutron method slope gradients in field moisture were not easy to detect.
Manganese and Iron Solubility Changes as a Factor in Tile Drain Clogging: I. Observations During Flooding and Drying
Authors: Grass L. B. , MacKenzie A. J. , Meek B. D. , Spencer W. F. 
Published: July 2010

AbstractA field study of waterlogging and subsequent drying of the soil profile has shown that under irrigation culture in Imperial Valley reducing conditions became prevalent. Reducing conditions, as indicated by declining Eh values, became most favorable for dissolution of Mn and Fe near the soil surface. However, the concentrations of Mn2+ and Fe2+ were lowest near the surface, probably because of their leaching from this zone, and the shorter time of contact between soil solution and soil particles. The concentration of Fe2+ and Mn2+ were higher in the deeper horizons of the soil profile.In the plow layer, the reducing intensity increased, beginning 9 m away from the tile and reaching a maximum 18‐ to 23‐m from the tile drain. The Eh levels in the soil profile declined immediately after irrigation began and rose immediately after irrigation stopped indicating the importance of atmospheric oxygen to the oxidation‐reduction status and, therefore, to the solubility of iron and manganese compounds. Soluble organic carbon apparently was not related to the concentration of Mn2+ or Fe2+ in the soil solution even though the decomposition of soil organic matter is important in oxidation‐reduction reactions in the soil profile.
Manganese and Iron Solubility Changes as a Factor in Tile Drain Clogging: II. Observations During the Growth of Cotton
Authors: Grass L. B. , MacKenzie A. J. , Meek B. D. , Spencer W. F. 
Published: July 2010

AbstractVarious levels of oxidation‐reduction develop in the soil profile during the irrigation and growing season of the cotton (Gossypium hirsutum L.) crop. Reducing intensity increased with depth during the growing season and reached maximum intensity at the 6.10‐m depth. Reducing conditions favorable to increased solubility of Fe and Mn were observed in the surface horizons of the profile during most of the season.Changes in the solubility of manganese and iron occurred with changes in the oxidation‐reduction status in the soil profile. Manganese began to dissolve at 400 mV and became significant at less than 300 mV. Increased concentration of nitrate retarded reduction of oxidized Fe and Mn compounds. The salinity of the soil solution affected the concentration of soluble manganese and iron. The presence of NO3‐ ‐N in the soil solution in amounts >0.2 ppm retarded the dissolution of Mn compounds.The solubility of manganese and iron can probably be controlled by controlling or regulating the oxidation‐reduction status of the soil profile by reducing the waterlogging period after irrigation to a minimum.
The Dissolution of Complex Ferric Phosphates Under Controlled Eh and pH Conditions
Authors: Williams B. G. , Patrick W. H. 
Published: July 2010

AbstractThe dissolution of complex ferric phosphates, CaFe2H4(PO4)4 · 8H2O and KFe3H14(PO4)8 · 4H2O, was studied in a reduced chemical system. Both salts dissolved incongruently to release calcium and phosphorus in a molar ratio of 1:2 and solid FePO4. Below an Eh of — 200 mV further P was released due to FePO4 dissolution. Potassium ferric phosphate crystals dissolved rapidly with complete release of K, whereas dissolution of calcium ferric phosphate was retarded probably due to interference by precipitated FePO4. The solubility of precipitated FePO4 differed slightly from that observed with crystalline strengite and at pH 6 and 7, ferric hydroxides apparently entered into the reaction.
Selective Distribution and Labile Pools of Micronutrient Elements as Factors Affecting Plant Uptake
Authors: Graham E. R. 
Published: July 2010

AbstractA study of the selective distribution of the nutrient elements Mn, Fe, Zn, Co, and Cu and plant response for soils from Colorado, Nebraska, Missouri, and Florida showed that selective distribution was related to plant response.The labile pool expressed in ppm for the elements Mn, Fe, Zn, Co, and Cu may be plotted against the selective distribution resulting in the best relationship between soil characteristics and plant uptake. It appears that the selective distribution labile pool plot will have universal application as a diagnostic method for assessing the fertility level of Mn, Fe, Zn, Co, and Cu.
Scanning Electron Microscopy of Hydrous Metal Oxide Crusts Intercalated in Naturally Weathered Micaceous Vermiculite
Authors: Jackson M. L. , Lee S. Y. , Brown J. L. , Sachs I. B. , Syers J. K. 
Published: July 2010

AbstractScanning electron microscopy (SEM) of the weathering products of trioctahedral mica, chemically weathered in nature to micaceous vermiculite (14 and 10Å spacings by X‐ray diffraction), revealed occasional deposition of hydrous metal oxide crusts on intermittent cleavages interspersed at intervals among chemically clean (001) surfaces. Examination by SEM of layers through pores or holes, and along (hkO) fractures through the (001) planes, revealed that the intercalated crusts were 1–15µm thick with sequences of hundreds of clean 14Å crystallographic layers between each crust layer. The pores may represent weathering out of 238U fission tracks resulting from impurities in the original micas.Treatment of a micaceous vermiculite flake with citratebicarbonate‐dithionite (CBD) produced a large number of smooth, thin phyllosilicate flakes which had planar areas at least one‐half that of the original untreated flake; hundreds of smaller flakes were released by this treatment. Natural weathering apparently formed cracks in the large flakes both in the (001) and (hkO) crystallographic directions. The metal oxides removed by CBD cemented the mica pseudomorphs in the untreated sample. The holes and fractures along (hkO) planes apparently permitted a diffusion of Fe3+ and Al3+ from the octahedral positions into the crusts during the geochemical conversions of biotite to micaceous vermiculite and may relate to the associated lowering of layer charge.
Effect of Two Nonionic Surfactants on Adsorption and Mobility of Selected Pesticides in a Soil‐System
Authors: Huggenberger F. , Letey J. , Farmer W. J. 
Published: July 2010

AbstractThe effect of two nonionic surfactants on the adsorption and mobility of lindane, diuron, and atrazine in soil columns was studied. A wide range of surfactant concentrations was used in this study. Adsorption of the pesticides by soil from a surfactant solution was inversely related to the leaching of the pesticides through the soil in presence of the surfactants. Low concentrations of both surfactants did not influence adsorption and mobility of the pesticides. A marked increase in the adsorption and reduction in the mobility of the pesticides was observed with 500 ppm Aqua Gro and 2,000 ppm Soil Penetrant. At concentrations of 5,000 ppm and 10,000 ppm, both surfactants decreased the adsorption and increased the mobility of lindane and diuron, but did not influence the adsorption and mobility of atrazine. An attempt was made to explain the mechanisms by which the two surfactants influence adsorption and mobility of the pesticides using the concept of micelle formation and critical micelle concentration.
Carbohydrases in Soil as Affected by Successional Stages of Revegetation
Authors: Pancholy Sunil K. , Rice Elroy L. 
Published: July 2010

AbstractAddition of plant materials from the first successional stage of old‐field succession caused a continuous increase in the microbial population and in activities of amylase, invertase, and cellulase for 45 days, the duration of the experiment. On the other hand, addition of plant materials from an intermediate successional stage or the climax stage resulted in an initial increase in the microbial population and in the activities of the three carbohydrases with a leveling off or decrease after 30 days. Type of organic matter added appeared to be responsible for the higher activities of the carbohydrases during the early stages of old‐field succession.
Loess Distribution as Revealed by Mineral Variations
Authors: Kleiss H. J. , Fehrenbacher J. B. 
Published: July 2010

AbstractThe apparent physical uniformity of various loess deposits has often led in the past to conclusions of uniform composition and constant rate of deposition for loess formations. These assumptions have been used in many evaluations of soil development and in explaining the distribution of various soils. The existence of identifiable increments of characteristic composition within Peoria Loess not only indicates compositional variations but permits evaluation of the regional distribution of individual loess increments. Unique mineralogy (particularly clay‐mineralogy) of the loess increments is attributed to major changes in the origin of valley loess source sediments.The consistent identification and pattern of four distinct zones within Peoria Loess in Illinois east of the Illinois River Valley reveal that the rate of loess deposition has not been constant. Rather, the upper younger loess increments are most dominant and more widely distributed and therefore most important as soil forming material. This implies that the soils of the maturity or development sequence in Illinois have all formed in the same relatively young increment of Peoria Loess. The characteristies of these soils which vary from weakly‐ to moderately‐developed Udolls to very strongly‐developed Albaqualfs cannot be attributed to their age differences.
Quantitative Calcium Carbonate Equivalent Determination in the Field
Authors: Holmgren George G. S. 
Published: July 2010

AbstractA simple volume calcimeter can be constructed from a 50‐cc and a 20‐cc plastic syringe. To operate, a weighted quantity of soil is placed in the large syringe and 5 cc of 10% HCl is drawn into the small syringe. The tips are then joined together through a connecting sleeve and the acid is injected into the soil. The volume of CO2 produced is measured in either or both syringes, depending on the amount.An array of sample weights to yield 1 cc CO2 for 1% CaCO3 equivalent at various temperatures and elevations is provided. This array is approximated by the relation W = (118‐13h)/T where W = weight of sample in grams, h = elevation in kilometers, and T = temperature, oK. Soluble CO2, ranging from 7.3 cc at 5C to 3 cc at 35C, must be added to the observed volume to obtain the true volume of CO2 released.An alternate procedure using a constant sample weight of 0.33 grams is also described. Directions are given for constructing a simple hand balance to weight this amount in the field, and a nomograph is provided to facilitate calculations.With these procedures, CaCO3 equivalent can be determined within 1–2% absolute over the range 0–50%. These errors may be reduced at lower CaCO3 equivalent values by increasing the sample size.
Simultaneous Transport of Chloride and Water During Infiltration
Authors: Kirda C. , Nielsen D. R. , Biggar J. W. 
Published: July 2010

AbstractDisplacement of chloride during infiltration was studied using soil columns for two cases: chloride initially spread on the soil surface; and chloride initially mixed with the soil. Chloride was applied as CaCl2 labeled with 36Cl. Its activity in counts per minute was scanned with a GM counter along a 2.5‐cm wide window slit in the columns. In conjunction with the chloride activity measurement, gamma‐ray attenuation measurement was used for monitoring the water content distribution during the simultaneous flow of chloride and water. Treatments included different levels of initial soil water content and different levels of water saturation at the soil surface during infiltration. With a numerical method the equations describing vertical water flow and miscible displacement of chloride were solved simultaneously. Experimental and calculated chloride distributions were in agreement. Chloride apparent diffusion coefficients estimated for pore water velocities less than 0.01 cm min‐1 were nearly equal to that for moleculer diffusion only. Initial soil water content did not influence the depth of chloride displacement for a given quantity of water infiltrated; whereas, keeping the water content at the soil surface below saturation resulted in a deeper and more complete displacement of chloride.
Chemical Properties of Acid‐Sulfate Soils Recently Reclaimed from Florida Marshland
Authors: Calvert D. V. , Ford H. W. 
Published: July 2010

AbstractAcid soil layers, with pH as low as 3.0, were found in the subsurface horizons of soils derived from marine sediments and have been recently developed into citrus groves. Soil layers with acidity varying from pH 3.0 to 7.7 and sulfate content from 0.5 to 39.0 meq/100 g of soil were compared for their capability of producing acid‐sulfates. Lime requirements of selected acid layers were found to be as high as 4.5 meq of CaCO3 equivalent per 100 g of soil. The acid‐sulfate potential (oxidation of reduced sulfur to H2SO4) accounts for the reduction of pH of the reclaimed soils. The sulfate content of soil layers was often in excess of 2,000 ppm when the soil pH after oxidation with H2O2 was below 3.0 and was dependent on oxidizable sulfur content of the sample and buffering capacity of the soil. Oxidized soil layers with pH values below 3.5 released soluble Al and Fe up to 275 ppm and 100 ppm, respectively.
Evaluation of Various Extractants for Available Soil Sulfur
Authors: Hoeft R. G. , Walsh L. M. , Keeney D. R. 
Published: July 2010

AbstractThe S status of 49 Wisconsin soils was evaluated in field studies using alfalfa (Medicago sativa) as the test crop. The effectiveness of six soil S extractants for predicting yield and S uptake response to applied S were evaluated by means of correlation analyses. The best extractant, considering all dependent variables and the S range, mean and standard deviation for each procedure, was 2N HOAc containing 500 ppm P as Ca(H2PO4)2 · H2O [Ca(H2PO4)2‐HOAc]. The correlation between extractable S and response to applied S was not improved by inclusion of percent organic matter, percent sand, or subsoil SO4‐S in the regression equation. However, inclusion of soil pH with extractable S did significantly improve the prediction of S response.The best equation for prediction of yield response to applied S in the field was: Yield response (metric tons/ha) = 50.81 − 7.22 pH − 8.19 S + 1.171 (pH × S) + 0.167 (S)2 − 0.00341 (pH × S)2 where S is the ppm of S extracted with Ca‐(H2PO4)2‐HOAc. Significant response to applied S would be expected on soils having a calculated yield response of 0.40 metric tons/ha or greater when extractable S is between 6 and 10 ppm S. Soils testing less than 6 ppm would be expected to respond and those testing greater than 10 ppm S would not be expected to respond to application of S, regardless of the calculated response value. Use of the regression equation and the limits of 6 and 10 ppm S resulted in correct prediction of S response at 77.6% of the field sites.
A Precision Dispenser for Dry Fertilizer Materials
Authors: Onken Arthur B. , Sunderman Herbert D. , Brashears Alan D. 
Published: July 2010

AbstractEquipment for the rapid and accurate dispensing of dry fertilizer materials is described. The dispensers consist of acrylic plastic cylinders containing a cylindrical cavity and are powered by a combination of hydraulic cylinders and solenoid valves. Hydraulic and electrical power are supplied by the transporting tractor. Three dispensing cylinders of different sizes are assembled to form a unit. One such unit is used for each row. The cylinders are designed with adjustable volume and may be used in various combinations, thus giving a high degree of flexibility. The amount of material dispensed with this equipment, though less precise than obtained by weighing, is more precise than obtained by using hand‐manipulated containers. The use of this equipment has sharply reduced the time and labor required to apply treatments.With the system described, either three rates of the same material or three different materials may be dispensed for application to each of four rows. Because of the modular design of the system, adaptations for specific needs can be constructed.
Flood and Seepage Water Sampling Techniques in Rice Fields Under Different Water Management Practices
Authors: Tanji K. K. , Biggar J. W. , Mehran M. , Henderson D. W. 
Published: July 2010

AbstractSampling equipment reported herein enables collection of flood and seepage waters to determine persistence and transport of chemicals applied in flooded rice culture (Oryza sativa L.). This system gives a capability of evaluating the effects of different chemical application methods (water‐applied, soil‐incorporated) and water management systems (static, flow‐through, and recycled).
Persistence and Competition Aspects of Rhizobium japonicum Observed in Soil by Immunofluorescence Microscopy
Authors: Bohlool B. B. , Schmidt E. L. 
Published: July 2010

AbstractFluorescent antibody was used to study persistence and competition of Rhizobium japonicum in soils. Strain 110 (USDA) attached to microscope slides was studied by FA‐staining after recovery of the slides from soil at various intervals. In the Clarion soil, reactive cells dropped from 32/microscope field, with 100% of the fields being positive, to 0.15/field, with only 10% positive fields in 120 days. In the Ulen soil, the drop was from 53/field (100% positive fields) to 2.5/field (40% positive fields) over the same period.The question of competition was approached first by varying the numbers of strain 110 added to constant but low numbers of the resident rhizobia flora of Clarion soil. Each treatment was used to inoculate plants and each nodule was tested separately with the homologous FA. Relatively high inoculant/resident ratios were needed to overwhelm the resident population. When the log of the numbers of introduced 110 was plotted against the percentages of 110 nodules, a sigmoidal curve emerged which may reflect a region of resistance characteristic for the resident R. japonicum population of that soil. A second approach involved the competitive ability of a known number of the introduced strain in the soil over a period of time. An initial population of 2.2 × 103 R. japonicum 110/g of Clarion soil, capable of initiating 85% of the nodules, formed only 55% and 45% of the nodules after 10 and 30 days, respectively, of incubation in the soil. This probably was a reflection of the inability of the initial added population to persist and maintain its numbers in the soil.
The Dynamic Character of a Chloritized Vermiculitic Soil Clay
Authors: Lietzke D. A. , Mortland M. M. 
Published: July 2010

AbstractInterlayer removal experiments using a chloritized vermiculitic soil clay showed its dynamic character by rapid alteration to vermiculite. The Ca/Mg cation exchange capacity of one sample dispersed ultrasonically and treated with dilute NaOH at pH 10 increased from 33 to 169 meq/100 g while the K/NH4 CEC remained in a range of 25 to 35. This particular sample contained all of the organic matter and the natural surface oxides. On standing for 12 days at lower pH, interlayer material was redeposited as indicated by Ca/Mg CEC reduction. Another sample of the same soil clay was pretreated in a conventional manner. The Ca/Mg CEC also increased from 24 to 113 and the K/NH4 CEC increased from 20 to 31 meq/100 g when treated with NaOH in the same manner. A standard prochlorite showed small but equal upward increases of both kinds of CEC. Deuteration experiments using a chloritized vermiculitic soil clay, a vermiculitic soil clay, and a standard prochlorite showed the easy accessibility of interlayer OH groups to deuteration at moderate temperatures. The interlayer OH groups of chloritized vermiculite showed deuteration at 68C, while the OH groups in the 2:1 structure of the vermiculitic soil clay started deuteration at 150C and those of the prochlorite at 200C.
Response of Corn in the Greenhouse to Soil Applied Zinc and a Comparison of Three Chemical Extractions for Determining Available Zinc
Authors: Coffman C. B. , Miller J. R. 
Published: July 2010

AbstractThe response of corn (Zea mays L.) to applied Zn on 12 Maryland soils was investigated in the greenhouse. Zinc was thoroughly mixed with soils at the rate of 0, 1.25, 2.5, 5, 10, 20, and 40 ppm Zn as zinc sulfate. Corn was grown for 30 days after emergence and dry matter yields were determined. The plant tissue was analyzed for Zn, Ca, Mg, K, and P.The application of Zn increased the dry matter yield of corn on only one of the 12 soils. As the Zn rate was increased, the Zn content of the corn usually increased. The level of Zn in the corn tissue above which no further significant increase in yield was obtained was about 12 ppm.Three chemical soil extractants were compared for determining available soil Zn. The Zn extracted by each of the three chemical extractants was correlated with the Zn content of the above ground portions of the corn plants. The correlation coefficient for the 0.05N HCl plus 0.025N H2SO4 extractant was 0.834, the 0.1N HCl extractant 0.854, and the 0.01M EDTA plus 1.0M (NH4)2CO3 extractant 0.787, respectively. The r values for all three extractants were statistically significant at the 1% level.The level of extractable Zn in an Othello soil which gave a significant dry weight increase in corn following the application of Zn was 0.3 ppm for the HCl plus H2SO4 extractant, 0.2 ppm for the HCl extractant, and 0.1 ppm for the EDTA plus (NH4)2CO3 extractant, respectively.