bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Tillage and Rainfall Simulation Date on Water and Soil Losses
Authors: Andraski B. J. , Mueller D. H. , Daniel T. C. 
Published: July 2010

AbstractTime of data collection relative to recent tillage may influence results of studies comparing water and soil losses among tillage systems. In this study a rainfall simulator was used at various times during the growing season over a 4‐yr period: (i) to compare water and soil losses from conventional (moldboard plow; CN) and three conservation tillage (CT) treatments: chisel plow (CH), till‐plant (TP), and no‐till (NT) and (ii) to observe major trends in runoff volumes as a function of rainfall simulation date. Above‐ground portions of corn (Zea mays L.) plants were removed prior to rainfall simulation. Trials were conducted in September 1980, June and July 1981, October 1982, and June and July 1983. Runoff volumes for CT treatments were consistently less than those observed for CN. For CT treatments, the volume of runoff (per unit rainfall) averaged 11, 20, and 52% lower than that observed for CN for the June 1983, July 1981 and 1983, and October 1982 sampling periods, respectively. Only the CH treatment significantly reduced runoff relative to CN soon after planting. Among CT treatments, CH was significantly more effective in reducing runoff in September 1980. For the remaining sampling periods, differences among CT treatments were not significant. An increase in residue cover consistently resulted in a decrease in sediment concentrations and, most often, a decrease in soil loss. Across all sampling periods, the NT treatment consistently decreased soil loss by 80 to 90% relative to CN, while soil losses for the CH and TP treatments varied, ranging from about 45 to 90% less than those for CN. Only in September 1980 did low runoff for CH result in soil loss which was less than that observed for NT.
The Selection Erosion of Plant Nutrients in Runoff
Authors: Sharpley A. N. 
Published: July 2010

AbstractThe enrichment of several P forms (Bray I, labile, inorganic, and organic), N, C, and K in runoff sediment was investigated for six soils of varying physical and chemical composition, using simulated rainfall (60 and 120 mm h−1). Differing enrichment ratios (ER) for C, N, and organic P (2.00, 1.61, and 1.47 avg for the six soils) indicate that erosion may reduce the C/N/organic P ratio of the remaining surface soil. Average ERs, for Bray I (2.45) and labile P (2.89) were significantly greater than for the other P forms (1.48). This was attributed to less aggregation of sediment compared to source soil for the major proportion (70%) of the runoff events studied. Phosphorus desorption‐sorption characteristics, buffer capacity (1.49), sorption index (1.56), equilibrium P concentration (1.80), and exchangeable K (2.46) were also enriched in runoff sediment compared to source soil. The logarithm of ER for each P form, N, C, and K was related to the logarithm of soil loss, which ranged from 10 to 800 kg ha−1. Statistically significant differences between regression equations for each nutrient indicate that more than one equation is needed to estimate different nutrient ERs. Nutrient ER was related to clay and specific surface area ER of the sediment. This is to be expected as the nutrients described are chemically associated with clay‐sized particles. The potential use of ERs in estimating the effect of erosion on soil fertility is discussed.
Recording Cone Penetrometer Developed in Reclamation Research
Authors: Hooks C. L. , Jansen I. J. 
Published: July 2010

AbstractA constant rate cone penetrometer has been developed for use in a strip mine reclamation project at the Univ. of Illinois. The device is capable of recording soil strength profiles to a depth of 112 cm. (44 in.). It utilizes a tractor‐mounted hydraulic coring machine as a source of movement. A chart recorder and data acquisition system are operated by 12 V DC electrical power. The penetrometer is effective in detecting soil layers where compaction is likely to inhibit root system development. It is useful in measuring soil strength in mine soils where the amount and depth of compaction may vary due to reclamation methods. Differences in soil strength may prove to be a clue to crop performance on reclaimed land.
Effect of Organic Acids on Aluminum Toxicity in Subsoils
Authors: Hue N. V. , Craddock G. R. , Adams Fred 
Published: July 2010

AbstractAluminum has long been recognized as a major limiting factor for root growth in acid subsoils, but little has been done to delineate toxic and nontoxic forms of soil‐solution Al. In an effort to determine if the presence of organic acids in soil solutions affected Al phytotoxicity, short‐term, split‐root experiments were conducted with cotton (Gossypium hirsutum L.) taproots as the growth indicator. Based on pure solution experiments, short‐chain, carboxylic acids can be divided into three groups as Al detoxifiers: (i) strong (citric, oxalic, tartaric), (ii) moderate (malic, malonic, salicylic), and (iii) weak (succinic, lactic, formic, acetic, phthalic). The Al detoxifying capacities of these acids were positively correlated with the relative position of OH/COOH groups on their main C chain, positions that favored the formation of stable 5‐ or 6‐bond ring structures with Al. In addition, analyses of soil solutions from several eluviated acid horizons (E, EB, BE) revealed the presence of several organic acids whose concentrations were generally higher in forested than in cultivated soils. Based on these concentrations, total solution Al (as measured by ICAP) was partitioned into monomeric Al (Al3+ + hydroxy‐Al species) and complexed Al (Al‐organic acid complexes). The latter accounted for 93 and 76% of the total solution Al concentrations of the two acid subsoils into which elongation rate of cotton taproot was studied. Root growth was significantly correlated with monomeric Al but not with total Al in soil solutions.
The Spatial Variability of Nitrogen‐15 and its Relation to the Variability of Other Soil Properties
Authors: Selles F. , Karamanos R. E. , Kachanoski R. G. 
Published: July 2010

AbstractThe spatial variability of natural 15N abundance of a cultivated Chernozemic soil and its native prairie counterpart were smaller than that of total N, organic C, and the C/N ratio. Further, the number of samples required to estimate the true mean of total N with a given precision at various probability levels were twofold those required to determine the mean 15N abundance in both soils. The variability of organic C was > 10 times that observed for total N. The results of this study indicate that the spatial variability of the natural 15N abundance of total soil N in the surface horizons may reflect the isotopic composition of the nitrogenous substances entering the soil system or changes in the isotopic composition of soil N due to humification processes, probably induced by variations in topographic and microrelief features of the soil.
Simultaneous Determination of Moisture, Organic Carbon, and Total Nitrogen by Near Infrared Reflectance Spectrophotometry
Authors: Dalal R. C. , Henry R. J. 
Published: July 2010

AbstractNear infrared diffuse reflectance spectrophotometry, within the wavelength range 1100 to 2500 nm, was investigated for use in the simultaneous prediction of the moisture, organic C, and total N contents of air‐dried soils. An infraAlyzer 500 C (Technicon Instruments Corp.) scanning spectrophotometer was used to obtain near infrared reflectance of soils at 2‐nm intervals. Calibration equations for each of the soil constituents studied were based upon selection of the best combination of three wavelengths in a multiple regression analysis. The wavelengths selected for moisture, organic C, and total N, respectively, were 1926, 1954, and 2150 nm, 1744, 1870 and 2052 nm, and 1702, 1870 and 2052 nm. The standard errors of prediction for finely ground samples (<0.25 mm) from the top layers (0‐0.1, 0.1‐0.2, 0.2‐0.3, 0.3‐0.6 m) were 0.58, 0.16, and 0.014% for moisture, organic C, and total N, respectively. The standard errors of prediction, however, were much larger for coarsely ground soils (<2 mm), soils containing low amounts of organic C (<0.3%) and total N (<0.03%), and for those with a wide range in colors. Within a narrow range in soil color and at moderate amounts of organic matter (0.3–2.5%C), the near infrared reflectance technique provides a rapid, nondestructive, and simultaneous measurement of moisture, organic C and total N in soils
Use of Boundary Lines in Establishing Diagnostic Norms
Authors: Walworth J. L. , Letzsch W. S. , Sumner M. E. 
Published: July 2010

AbstractWhether utilizing a critical value or a nutrient balance system such as the Diagnosis and Recommendation Integrated System (DRIS) for interpreting plant tissue composition, determination of accurate optima is of paramount importance. Two procedures for determining such optima, one using the mean of a high yielding population, the second establishing yield maxima at all nutrient values (henceforth termed the boundary line approach) were contrasted. Ear leaf nutrient composition and associated yield information were collected on over 8000 maize (Zea mays L.) samples from around the world. Values of N/DM, P/DM, K/DM (DM = dry matter), P/N, N/K, and K/P as well as the DRIS indices for N, P, and K were plotted against grain yields. Boundary lines confining the resultant scatters of points were then mathematically described. The boundary lines define yields that may occur under a given set of conditions and can be used to determine plant tissue optima, or as a yield specific alternative to the conventional critical value system. In addition, the maximum yield possible at any given compositional value may be predicted from boundary lines. A comparison of the optima determined via the boundary line approach and those estimated by the mean of the high yielding population revealed extremely small differences indicating that either method is acceptable for estimating these parameters.
Effect of Fertilizer Phosphorus Placement Depth on Winter Wheat Yield
Authors: McConnell S. G. , Sander D. H. , Peterson G. A. 
Published: July 2010

AbstractField studies were conducted with winter wheat (Triticum aestivum L. ‘Centurk 78’) at nine locations in southwestern, central, and eastern Nebraska in 1982 and 1983 to determine the effect of phosphorus (P) placement depth (0, 5, 10, and 15 cm). As a comparison to these depths, seed placed P, soil surface placed P, and no P treatments were used. A rate of 11 kg P ha−1 was applied. Soil great groups were either Argiustolls or Argiudolls with surface soil Bray and Kurtz no. 1 P levels ranging from 4 to 9 mg kg−1 and pH values ranging from 5.5 to 7.5. Grain yield was increased by added P in both years though magnitude of response varied at different locations. A linear and quadratic response to depth was evident in both years, though variation occurred between locations. Optium depths of P placement for maximum grain yield occurred at 11.9 cm in 1982 and 10.4 cm in 1983. No differences between either the best depth (10 cm) and seed treatments or the surface and seed treatments were found, indicating that, depending on management situations, these methods of P application could be used interchangeably. Total P uptake was increased by P applications in a manner similar to grain yield. Phosphorus uptake of the seed treatment and the best depth treatment at several growth stages (Feekes' stages 2.0, 6.0, 10.0, 10.5, and 11.4) was compared. An early advantage (stage 2.0) of the seed treatment was not evident at harvest, indicating that early P uptake is not necessary for maximum yield. The number of heads and seed weight were both increased due to applied P in both years and seed weight responded linearly to depth in 1982. No effect on the seed number per head was found.
Earthworms as a Factor in the Reduction of Soil Crusting
Authors: Kladivko Eileen J. , Mackay Alec D. , Bradford Joe M. 
Published: July 2010

AbstractSurface soil crusting after heavy rainfall is a problem on many cultivated soils. The objective of this study was to investigate the effect of earthworms (Lumbricus rubellus) on the aggregate stability and infiltration rate of a soil and then assess the susceptibility of this soil to surface crusting. The effect of 0, 15 (250 m−2), or 30 (500 m−2) earthworms pot−1 on a Raub silt loam (Aquic Argiudolls) to which no, soybean [Glycine max (L.) Merr.] or corn (Zea mays L.) residue had been added was studied in 16‐L pots over a 54‐d period in the greenhouse. Earthworms increased both mean weight diameters (MWD) and water‐stable aggregates > 2mm when determined on initially moist soil. In the absence of earthworms, steady‐state infiltration rates on the Raub soil were 22 µm s−1 (8 cm h−1). Addition of 15 and 30 earthworms pot−1 to soil containing crop residues, increased infiltration rates to 181 and 328 µm s−1 (65 and 118 cm h−1), respectively. The susceptibility of the undisturbed soil in the 16‐L pots and of sieved, repacked soil to surface crusting under simulated rainfall was evaluated by measuring corn seedling emergence. Ten days after planting and simulated rainfall (6.25 cm h−1), 85 to 100% of corn seedlings had emerged in the undisturbed soil in which earthworms were active, whereas in the absence of earthworms only 50 to 52% of seedlings had emerged. When the sieved soil that had received residues and earthworms was exposed to simulated rainfall, 40 to 73% of seedlings had emerged at 10 d, and by 16 d 80 to 88% had emerged. This compares with only 38% emergence in soil to which neither residue nor earthworms was added. Through their feeding, casting, and burrowing activity, earthworms are an important factor in the reduction of surface crusting.
Binding of Ionic and Neutral Herbicides by Soil Humic Acid
Authors: Madhun Yousef A. , Freed V. H. , Young J. L. 
Published: July 2010

AbstractThe gel filtration method of Hummel and Dreyer has been used for the study of binding of bromacil (5‐bromo‐3‐sec‐butyl‐6‐methy‐luracil), diuron [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea], chlortoluron [3‐(3‐chloro‐4‐methylphenyl)‐1,1‐dimethylurea], simazine (2‐ chloro‐4,6‐bis‐ethylamino‐s‐triazine), glyphosate [N‐(phosphonomethyl) glycine], and diquat (1,1‐ethylene‐2,2‐bipyridylium ion) by humic acid. The chromatographic method was found germane for the study of the ionic, as well as the nonionic herbicides. The results expressed as the number of moles of herbicide complexed per unit weight humic acid indicated the utility and reliability of the procedure for the quantitative evaluation of binding. Valid quantitative data on the interaction of herbicides with humic acid would be indispensable for the assessment of these chemicals mobility and transport in soil and water environments.
Analysis of Humic Acids by Solution and Solid‐state Carbon‐13 Nuclear Magnetic Resonance
Authors: Schnitzer M. , Preston C. M. 
Published: July 2010

AbstractEighteen humic acids (HA's) were characterized by chemical analyses, infrared (IR) and electron spin resonance spectra, and by solution and solid‐state cross polarization magic‐angle spinning (CPMAS) 13C nuclear magnetic resonance (NMR). The main objectives of this investigation were: (i) to compare the solution and solid‐state 13C NMR spectra of the HA's; (ii) to examine effects of different delay times (D1) on the solution spectra; and (iii) to find reasons for the failure of 13C NMR to detect the presence of significant concentrations of phenolic C in unmethylated HA's. Compared to solution spectra, CPMAS spectra consisted of relatively few, broad bands, indicative of considerable overlapping of individual signals, especially in the aliphatic regions. Proportions of aliphatic C determined by solution 13C NMR at D1 = 0.74 s were greater than those obtained at D1 = 1.90 s and by CPMAS 13C NMR (where D1 = relaxation delay). By contrast, proportions of aromatic C and aromaticities were greatest at D1 = 1.90 s. The highest values for CO2H groups were obtained by CPMAS 13C NMR and approached total acidities; values measured by solution 13C NMR at D1 = 1.90 s were intermediate, while those determined by solution 13C NMR with D1 = 0.74 s were the lowest and closest to CO2H concentrations determined chemically. Because the presence in HA's of significant concentrations of phenolic OH groups has been confirmed by several independent methods, it is possible that in 13C NMR spectra of HA's, signals arising from phenolic C are shifted downfield so that they overlap with resonances of C in CO2H groups. The net result is that CO2H groups are overestimated and phenolic OH groups underestimated.
Equations for Determination of Nitrogen‐15 Labeled Dinitrogen and Nitrous Oxide by Mass Spectrometry
Authors: Mulvaney R. L. , Boast C. W. 
Published: July 2010

AbstractIn mass spectrometric procedures recently developed for determination of 15N‐labeled dinitrogen (N2) and nitrous oxide (N2O) evolved from soils, calculations are performed to determine the mole fraction of 15N in the N pool from which this N2 or N2O was derived (15XN), and a fraction proportional to the amount evolved (d). The equations originally derived for these calculations are based on several approximations and are so simple that they can easily be performed using a handheld calculator. Modern ratio mass spectrometers are usually equipped with an on‐line programmable calculator or computer to process the digital output from the integrating ratiometer, which has made it practical to calculate 15XN and d using equations based on fewer approximations than the equations previously derived. Refined versions of the equations are derived in this paper. The refined equations are much more complicated than the original equations, but they are more accurate and permit the use of fertilizers containing <20 atom % 15N in studies of denitrification.
Effect of Soil Organic Matter Accumulation on Potassium and Ammonium Quantity‐intensity Relationships
Authors: Evangelou V. P. , Karathanasis A. D. , Blevins R. L. 
Published: July 2010

AbstractQuantity‐intensity (Q/I) relationships for potassium (K+) and ammonium (NH4+) in a Maury silt loam soil (fine‐silty, mixed, mesic, Typic Paleudalfs) under long‐term conventional and no‐tillage management were investigated to determine changes in solute‐soil interactions brought about by differential organic matter accumulation. To obtain differences in organic matter content, representative soil samples were collected from a field experiment that was established in the spring of 1970, involving treatments of conventional tillage with no nitrogen (N) fertilizer (CT‐control) and no‐tillage with 336 kg N ha−1 applied annually (NT‐high N). The results of the study reveal that K+ and NH4+ equilibrium concentration ratios (CRk*, CRNH*4) along with the linear potential buffering capacities (PBCK, PBCNH4) were greatly affected by soil organic matter accumulation resulting from no‐tillage and N addition. CRK* and CRNH*4 were higher in the NT‐high N than the CT‐control system (19.61 and 12.11 vs 6.61 and 2.15 [(mol L−1)1/2 × 103], respectively). Furthermore, the PBCk was slightly greater but not significantly different in the NT‐high N (28.4) than the CT‐control system (26.3) [cmol(+) kg−1)/(L mol−1)1/2]. Potential buffering capacity for NH4+ (PBCNH4) was significantly smaller in the NT‐high N (17.5) than the CT‐control system (26.0). The affinity of the NT‐high N soil exchange phase for both K+ and NH4+ was significantly lower than that of the CT‐control exchange phase. The affinity for K+ exhibited by NT‐high N system was significantly greater than that for NH4+ (1.71 vs. 1.23). In CT‐control systems only slight differences (statistically nonsignificant) were observed in affinities for NH4+ and K+ (2.62 vs. 2.47). Potential buffering capacity for NH4+ and K+ appeared to be a function of the affinity of the exchange phase for each cation and the magnitude of the cation exchange capacity (CEC). Despite higher CEC values in the NT‐high N system, a proportional increase in the PBC was not observed because the NT‐high N exchange phase exhibited a lower affinity for NH4+ and K+ ions than the CT‐control did.
Nature and Micromorphology of Carbonate Glaebules in Some Vertisols of India
Authors: Mermut A. R. , Dasog G. S. 
Published: July 2010

AbstractThe mineralogical and chemical nature, size, shape, distribution, and orientation of carbonate glaebules in two Chromusterts and two Pellusterts of India were studied. Micromorphology and 14C analysis of these features indicated their pedogenic origin. X‐ray diffraction and chemical analyses showed that calcite was the only carbonate mineral present and that there were inclusions of primary minerals and other soil constituents. Two morphological groups consisting of black and white glaebules were observed. Black carbonate glaebules had relatively older 14C dates (26 000 yr BP) and higher amounts of Fe and Mn, and were usually smaller (0.5‐cm diam) than the white ones (1.0‐cm diam, 4000–14 000 yr BP). Since the black carbonate glaebules were coated by Fe and Mn oxides, they therefore had a smoother surface morphology. The majority of the glaebules had cavities that were partly or entirely filled by carbonate neoformations. Intersecting sets of glaebules with an inclined, banded orientation pattern in the subsoil were interpreted as a sign of stress phenomena, and the quantitative distribution and orientation pattern of these features suggested a self‐mixing process. The study also indicated the possibility of using carbonate glaebules as a criterion in the classification of Indian Vertisols.
A Portable Constant‐rate Cone Penetrometer
Authors: Lowery Birl 
Published: July 2010

AbstractA portable, constant‐rate, recording cone penetrometer was designed and field tested to eliminate operator‐associated variability with hand‐pushed penentrometers and to overcome the limited portability of tractor‐mounted penetrometers. An average penetration rate of 8.3 mm s−1 was achieved with a small high‐torque DC motor connected to a rack‐pinion gear system. The motor and gear system was mounted on a tripod that allowed the unit to be leveled and provided for a maximum penetration depth of 0.61 m. Force of penetration, as a function of depth, was determined with four strain gages mounted on a proving ring and a rotary encoder. The encoder provided a remote signal to drive a x‐y plotter providing 0.61 mm of chart per millimeter of soil penetrated. The coefficient of variation for the rate of penetration was 3.4%. The rate of penetration remained approximately constant when tested over a range of soil densities from 0.9 to 1.9 Mg m−3.