bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Management and Nitrification Inhibitor Effects on Nitrogen‐15 Urea: I. Yield and Fertilizer Use Efficiency
Authors: Walters D. T. , Malzer G. L. 
Published: July 2010

AbstractNitrification inhibitors (NI) are sometimes recommended for use with ammoniacal fertilizers in corn (Zea mays L.) production to improve fertilizer N use efficiency (FUE). The objectives of this experiment were to evaluate the effects of the NI nitrapyrin [2‐chloro‐6‐(trichloromethyl) pyridine] application on yield and FUE of irrigated corn, and to monitor the fate of a single application of 15N‐enriched urea during a multiyear period in both soil and plant. Treatments included a factorial combination of two N rates (90 or 180 kg urea‐N ha−1 yr−1) applied during a 3‐yr period, with or without a NI and with or without incorporation, plus a zero‐N control. Twenty‐seven nonweighing lysimeters were used to quantify leaching load. Treatment effects on yield and FUE differed each year due to interactions of climate and N‐management variables. Nonincorporated urea + NI reduced grain yield when leaching load was low and increased yield at the 90 kg ha−1 N rate when leaching load was high. Maximum FUE occurred at the 90 kg ha−1 N rate when leaching load was low. The NI increased FUE only at the 90 kg ha−1 N rate when leaching load was high. Incorporation of urea + NI reduced plant recovery of fertilizer‐derived N (FDN) in the year of application, but resulted in increased uptake of residual FDN in subsequent years. Incorporation of NI with moderate N rates coupled with conservative irrigation management should reduce the risk of yield loss and minimize NO3 movement to groundwater.
Pedogenic Iron Oxide Trends in a Marine Terrace Chronosequence
Authors: Aniku Jacob R. F. , Singer Michael J. 
Published: July 2010

AbstractDepth to maximum concentration and maximum horizon concentration of whole‐soil dithionite‐extractable Fe (Fed) and Al (Ald) increased from the youngest (105 000 yr) to oldest (600 000 yr) terrace in a California marine chronosequence. The ratio Fed/Fet (total Fe) for clays extracted from horizons of maximum pedogenic expression also increased with terrace age, while the clay Feo (oxalate extractable)/Fed decreased. These data suggest that there is a progressive transformation of ferrihydrite to crystalline Fe oxides with time. Relative concentrations of goethite in the clay samples were estimated from the integrated intensity of the d110 line. The intensity of the goethite d110 line increased with terrace age. Degree of Al substitution in goethite was calculated from d111 and d110 peak positions. Aluminum substitution in the geothites increased with terrace age. The relative concentrations increased from the youngest to next‐to‐oldest terrace, then decreased, but the degree of crystallinity increased from youngest to oldest terrace. Goethite was the dominant pedogenic Fe oxide in these four soils. Mean annual temperature of 14 °C, moderate precipitation (716 mm yr−1), and frequent fog appear to favor the transformation of ferrihydrite to goethite.
Soil‐Atmosphere Access Chamber and Analytical Assembly to Monitor Soil Aeration
Authors: Mukhtar S. , Baker J. L. , Kanwar R. S. 
Published: July 2010

AbstractA reliable method for soil‐aeration monitoring is needed. This study was conducted to develop and test a sampling and analysis technique to be used in rapid and nondisruptive monitoring of soil atmospheres. A specially constructed soil‐atmosphere access chamber and a dual‐action syringe sampling assembly were used to obtain atmosphere samples at various depths within the soil profile in laboratory columns and field plots. The O2 contents of these samples were measured by using a portable O2 meter, a probe, and a custom‐made sample analysis reservoir. For comparison, an existing method was used to obtain simultaneous O2‐concentration measurements. Laboratory testing proved the new sampling technique to be fast and free of outside contamination. Use of the dual‐action syringe sampling assembly helped obtain representative samples at a given depth both in the field and in the laboratory. Identical O2 concentrations measured using the new technique and the previously available method suggested that this new soil‐atmosphere sampling and analysis technique is reliable. Very small standard deviations among repeated measurements of O2 concentrations at various sampling depths in both laboratory columns and field plots suggest small variations in the soil atmosphere samples obtained by using this access chamber and the analytical assembly.
Conifer Seedling Growth Response to Soil Type and Selected Nitrogen Availability Indices
Authors: Kraske Charles R. , Fernandez Ivan J. 
Published: July 2010

AbstractAlthough N is typically a growth‐limiting factor in northeastern forest soils, few studies have demonstrated the best analytical approach for determining available N in this heavily forested region. To address this information need, seedlings of balsam fir [Abies balsamea (L.) Miller], red spruce (Picea rubens Sarg.), and white pine (Pinus strobus L.) were grown for 26 wk in the greenhouse using soil materials representative of commercial forest sites in Maine. Soils included two O horizons and two B horizons from Spodosols derived in till, and an Ap and B horizon from an Inceptisol derived in marine sediments. Six different indices of available N were evaluated for each horizon, and results were compared with seedling‐growth parameters. Three available‐N indices were chemical and three were biological. Seedlings grew markedly better in O horizons than in mineral soils. Of the species examined, white pine had the greatest dry‐weight yields, and was the only species to exhibit visible evidence of root mycorrhizal infection. Although N‐availability indices were correlated with seedling‐growth parameters, the 1‐ and 2‐wk anaerobic incubations generally exhibited the highest correlation coefficients. Of the chemical indices, the simple KCl extraction appeared best correlated with seedling growth. Of the seedling characteristics examined, foliar N concentration was not highly correlated with soil N availability due to dilution effects. In contrast, foliar N uptake was highly correlated with N availability.
Estimating Forest Soil Quality from Terrain Measurements of Apparent Electrical Conductivity
Authors: McBride R. A. , Shrive S. C. , Gordon A. M. 
Published: July 2010

AbstractA portable, noncontacting electromagnetic induction meter was employed to measure the apparent electrical conductivity (ECa) of nonsaline, medium‐ and coarse‐textured forest soils on Manitoulin Island, Ontario. In simple linear regressions, bulk soil ECa was strongly correlated with ECe (saturated‐extract electrical conductivity), as well as exchangeable Ca, exchangeable Mg, and cation exchange capacity. Within the limited study area, these soil characteristics were thought to be major determinants of forest soil quality for red oak (Quercus rubra L.) production. Multiple stepwise regression showed that variations in exchangeable Ca and total Kjeldahl N concentrations accounted for a large proportion of the variation in ECa meter response (R2 = 0.871). The potential of this geophysical terrain measurement method as an integrator of edaphic properties important to forest site productivity is discussed.
Solar‐Radiation Transmittance of Flail‐Chopped Corn Residue Layers
Authors: Tanner C. B. , Shen Y. 
Published: July 2010

AbstractThe transmittance of solar (global) radiation through crop residues is required to model the influence of residue on the energy balance and temperature of the underlying soil in conservation tillage systems, but we could find no measurements of the transmittance of residue layers. The objective of this study was to devise ways to measure the transmittance of flail‐chopped corn (Zea mays L.) residue layers, to measure the reflectance and transmittance of the residue elements, to measure the transmittance of residue layers of different areal densities, and to see if global radiation models developed for crop canopies would be suited to predicting transmittance of residue layers. The solar reflectance of dry flail‐chopped corn stalk pieces was about 0.25 in the 400‐ to 700‐nm wave band and about 0.6 in the 700‐ to 2600‐nm band. The transmittance of residue pieces in these two bands was 0.005 and 0.02, respectively. The transmittance of layers of flail‐chopped residue was almost independent of the solar zenith angle because the bulk of the residue was comprised of stalk wall fragments that were essentially flat strips lying parallel to the surface with randomly oriented axes. The extinction coefficient of the residue for global radiation was about 1.70. This is 1.7‐fold greater than expected for randomly distributed flat, black elements. The extinction coefficient for solar radiation was not significantly different from that of thermal radiation (1.6), despite a large difference in element reflectance. We believe the large extinction coefficients resulted because residue elements were distributed uniformly rather than randomly. The similarity of extinction coefficients of solar and thermal radiation indicates forward scattering of solar radiation is negligible, probably because of the opacity and close packing of residue elements, which reduces interelement reflections. For crop radiation models to be applied to residue, they must be revised to account for both nonrandom element distribution and the close packing of residue elements on each other and on the soil.
Binary and Ternary Exchange Behavior of Potassium and Ammonium on Kentucky Subsoils
Authors: Lumbanraja J. , Evangelou V. P. 
Published: July 2010

AbstractPotassium‐Ca and NH4‐Ca exchange reactions in soils are often investigated in laboratory‐type studies. In these studies, it is assumed that the results from the binary exchange systems can be extrapolated to ternary (three ion) exchange systems using appropriate models. This, however, is rarely evaluated. This study deals with K‐Ca exchange in the presence and absence of added NH4 and NH4‐Ca exchange in the presence and absence of added K on the subsoil of three Kentucky soils, Eden clay loam (fine, mixed mesic Typic Hapludalf), Lowell clay loam (fine, mixed, mesic Typic Hapludalf), and Nicholson silt loam (fine‐silty, mixed, mesic Typic Fragiudalf). The experimental approach is based on the quantity/intensity concept in order to make the findings relevant to field conditions. The added NH4 decreased the linear potential buffering capacity for the K (PBCk) more than expected and increased the equilibrium activity ratio of K (ARoK) more than expected. The addition of K stimulated the adsorption of NH4 on high‐affinity sites. Added NH4 induced expansion, rather than collapse, of the vermiculitic interlayer. This suggests that the NH4 was not occluded or trapped, but rather specifically adsorbed in the vermiculitic interlayer. In essence, the added NH4 permits a greater fraction of the total surface charge to be available for exchanging cations due to the interlayer expansion. The soil that demonstrated the greatest potential for specific adsorption of NH4 was the Eden, followed by the Lowell and the Nicholson. The same order exists with respect to intensity of interlayer expansion. The above suggest that the simultaneous addition of K and NH4 in soil systems may influence the fate of NH4, such as, for example, the quantities leached as NH4, volatilized as NH3, and oxidized to NO3.
Characterization of Chemically Fixed Liquid Anhydrous Ammonia in an Illinois Drummer Soil
Authors: He X. T. , Mulvaney R. L. , Stevenson F. J. , Vanden Heuvel R. M. 
Published: July 2010

AbstractAnhydrous NH3 applied to soil is subject to chemical fixation by organic matter. A laboratory study was conducted to (i) determine the amount of N retained through chemical fixation of NH3 compared with the amount of NH4 fixed by clay, (ii) characterize the organic‐matter‐fixed NH3, and (iii) assess the biological availability of the fixed NH3. Nitrogen‐15 labeled liquid anhydrous NH3 was injected into a Drummer silty clay loam soil (2.07 g NH3‐N kg−1 soil), and the fixed 15NH3‐N was characterized by sequential extraction with Na4P2O7, KOH, NaOH, and dimethyl sulfoxide (DMSO). About 16% of the 15NH3‐N injected was fixed by the soil. Of the N fixed, 48% was accounted for by chemical fixation into the soil organic fraction, most of which was removed by sequential extraction, and 52% was accounted for as clay‐fixed NH4. Of the organic‐matter‐fixed 15NH3‐N, 55% was recovered in the fulvic acid (FA) fraction obtained by sequential extraction with Na4P2O7 and KOH; about equal amounts (17%) were recovered in the humic acid (HA) and humin fractions. The remainder (11%) was recovered in the NaOH and DMSO extracts. Most of the fixed 15NH3‐N in the FA fraction was recovered as either low‐molecular‐weight (LMW) fraction or nonhumic substances. The availability of the fixed 15NH3‐N (occurring as either organic‐matter‐fixed NH3 or clay‐fixed NH4) to soil microorganisms was estimated to be 13% after incubation with glucose for 7 d; from 20 to 22% was found to be potentially available to plants as estimated by distillation with MgO. Results indicate that NH3‐N newly fixed by organic matter occurs in forms that are less stabilized and more biologically available than the native soil N.
Statistical Comparison of SPOT Spectral Maps with Field Soil Maps
Authors: Agbu Patrick A. , Fehrenbacher Donald J. , Jansen Ivan J. 
Published: July 2010

AbstractThe field soil map is not the only appropriate standard for evaluating spectral maps. This study was undertaken to evaluate both the field soil map and the spectral map independently, according to the degree to which they minimize within, and maximize among, unit variability of pertinent soil properties. Two 3108‐ha areas in Ford County, east central Illinois were systematically sampled and soil properties were measured. Field and satellite‐derived maps were compared, using several approaches. The results showed that, generally, most of the variability was within map units. Of all the spectral maps, the Systeme Probatoire d'Observation de la Terre (SPOT) texture map was best, and the parameters used indicate that it was close to the field soil map. The mapping units used in the SPOT texture map were both more numerous and of a fundamentally different kind than the units on the field soil map. Units on the field soil map are defined in terms of soil properties that affect use and management, whereas units on the SPOT spectral maps are based directly on spectral properties only. Characterization of SPOT mapping units in terms of significant soil properties would be a necessary next step after generation of spectral maps, before they could be used for land management or land‐use planning. The data indicate that computer classification of SPOT digital data is a potentially useful approach to soil investigations.
Long‐Term Wheel Traffic Effects on Soil Physical Properties under Different Tillage Systems
Authors: Hill R. L. , Meza‐Montalvo M. 
Published: July 2010

AbstractThis study determined the effects of long‐term vehicular wheel traffic on soil physical properties for a Mattapex silt loam (fine‐loamy, mixed, mesic Aquic Hapludult) under different tillage systems. The site utilized a randomized complete‐block design with four replications of continuous‐corn (Zea mays L.) plots under no‐till and conventional till, both of which had controlled wheel traffic for 14 yr. Wheel‐traffic loads during the 14‐yr period had been confined to axle loads of <4.5 Mg. Wheel traffic generally increased bulk density and soil strength. Wheel traffic resulted in over a 50% increase in soil strength when compared with non‐wheel‐tracked areas. The relative soil strength increase from wheel traffic was less for no‐tilled soil than conventionally tilled soil, although the mean increase (∼40 kPa) was the same for both tillage systems. Wheel‐traffic effects on bulk density and soil strength decreased with depth and were largely dissipated by the 30‐cm depth. The presence of wheel traffic in the conventionally tilled interrows significantly reduced the pore volume of pores >15 µm in the upper 17.8‐cm portion of the soil, but did not cause similar reductions in the no‐tilled interrows. Conventionally tilled soil exhibited more pore space in the 15‐ to 0.1‐µm radius range that should retain plant‐available water. Wheel traffic did not exhibit statistically significant effects for the 15‐ to 0.1‐µm range. Neither tillage system nor wheel traffic adversely changed soil physical properties so much that detrimental conditions for plant growth would be encountered. Reasonable doubt exists regarding the necessity to subsoil this soil on a regular basis to alleviate the effects of wheel traffic or continuous no‐tillage management as long as small‐scale farm equipment has been used.
Nitrification Potential of Secondary‐Succession Upland Oak Forests: I. Mineralization and Nitrification during Laboratory Incubations
Authors: Donaldson Jennifer M. , Henderson Gray S. 
Published: July 2010

AbstractExperiments were carried out to examine factors regulating N mineralization and nitrification in upland oak (Quercus spp.) forests of the Missouri Ozarks. Soils were collected from three sites representing secondary oak succession. Sampling dates represented different stages in the phenological development of the vegetation during a 1‐yr period. Soils were incubated in the laboratory, and changes in soil NO3‐ and NH4‐N were measured, along with changes in populations of autotrophic NH4‐oxidizing bacteria. The NO3‐production curves during laboratory incubation were used to calculate three variables that describe potential nitrification. These variables were lag prior to NO3 accumulation, and initial rate and maximum rate of NO3 production. This nitrification potential is greater in more mature oak stands. Multiple regression analyses of these data show that nitrification in these sites is indirectly regulated by soil NH4‐N availability and pH. However, the strong sampling‐date effect on soil NH4‐N levels, lags in nitrification, and populations of NH4‐oxidizing bacteria suggest interactions between soil nitrification potential and possible inhibition by vegetation.
Effective Design for Small Flood‐Irrigated Field Plots
Authors: Ghodrati Masoud , Ernst Frederick F. , Jury William A. 
Published: July 2010

AbstractMany studies dealing with water flow in soil require water application through ponding. A method is described for the preparation of a large number of adjacent ponded field plots for experimental purposes. Individual plots are enclosed by corrosion‐resistant, metal strips extending 20 cm into the soil. A single border area around each group of plots functions as a buffer zone, similar to the outer zone of a double‐ring infiltrometer. Simultaneous uniform ponding of individual plots and the border area is achieved by a network of bubbler sprinkler units, with each plot having a separate water flow meter and valve unit to control the rate and amount of each irrigation episode. Such a system enabled study of the influence of macropore structure on the transport of various pesticides and dyes under continuous and intermittent flood irrigation.
Wheat Straw Decomposition and Changes in Decomposability during Field Exposure
Authors: Collins H. P. , Elliott L. F. , Papendick R. I. 
Published: July 2010

AbstractDescribing crop residue decomposition is important for assessing management practices that protect soil against wind and water erosion. Predicting wheat (Triticum aestivum L. em Thell) residue decomposition in conservation tillage systems requires information on C mineralization and changes in residue decomposability. The principal component of wheat residue is the stem. Wheat straw decomposition at the soil surface was followed during field and laboratory inclubation studies. Straw samples were collected on nine dates during 377 d of field exposure and analyzed for weight loss. Total C, soluble C, carbohydrate, N content, and C mineralization were measured periodically during the exposure period. Straw weight loss was 12% after 33 d and averaged 0.05% d−1 for the remaining exposure period. Cumulative weight loss was 33%. Total N, soluble C, and carbohydrate concentrations decreased 17, 73, and 66%, respectively, during field exposure. Total C concentration increased 6.2% after 94 d, then returned to the C concentration of the original straw. In the laboratory, C mineralization of straw taken from the field after ≥94 d was significantly (P < 0.001) lower than C mineralization of fresh residue. Cumulative CO2 evolution among samples that had been in the field for 94 to 377 d was not significantly different (P = 0.03). Amount and quality of soluble C was found to be important only during initial stages of fresh straw decomposition and was inconsequential for field exposed straw. Additions of cellobiose and N had no influence on C mineralization during laboratory incubation.
Indigenous Soil Factors Influencing Iron Chlorosis of Soybean in Calcareous Soils
Authors: Morris D. R. , Loeppert R. H. , Moore T. J. 
Published: July 2010

AbstractIron deficiency is the most prevalent and difficult to control of the plant‐nutrient deficiencies encountered on calcareous soils and may be especially severe for soybean [Glycine max (L.) Merr.]. This study was conducted to determine the predominant indigenous soil properties, i.e., those soil properties which are largely unaffected by environmental and management conditions, that influence Fe availability to soybean on calcareous soils. Three varieties of soybean were grown in a growth room in sand/soil mixtures of 23 calcareous soils that were selected to give wide ranges of clay, Fe oxide, CaCO3, and organic matter contents and exchange ion composition. Iron‐deficiency stress was quantified using visual chlorosis ratings in addition to chlorophyll and Fe concentrations of the plant tissue. The concentration of amorphous Fe oxide in the soil was an important factor influencing the uptake of Fe by soybean. Chlorophyll concentration of the plant tissue was negatively correlated with soil‐solution ionic strength and reactivity of the soil carbonate phase. The carbonate effect was likely due to the influence of the highly‐reactive carbonate phase on rhizosphere pH and its subsequent influence on effectiveness of the Fe‐stress response mechanism of soybean. These results differ from results of a previous study with sorghum, in which concentration and reactivity of the carbonate phase of calcareous soils had no influence on the incidence of Fe chlorosis. The different behavior of soybean and sorghum with respect to carbonate reactivity may be attributed to the different predominant Fe‐stress response mechanisms of these crops.
Portable Laser Scanner for Measuring Soil Surface Roughness
Authors: Huang Chi‐hua , Bradford Joe M. 
Published: July 2010

AbstractSoil surface elevations are commonly measured along a profile at relatively large grid spacings between 5 and 50 mm. This limitation in measurement technique allows the description of surface roughness due to tillage marks and large clods only on the order of ≥20 mm. A portable scanner was designed to measure soil topography at variable grid spacings down to submillimeter scales. The scanner consisted of an optical transducer for measuring soil surface elevation, a motor‐driven X‐Y traversing frame, a set of processing and control electronics, and a personal computer. The optical transducer was mounted on the carriage of the X‐Y traversing frame and was programmed to scan a maximum area of 1 by 1 m. The personal computer controlled the scanning and recorded elevation data. The system had no static noise and the combined frame vibration and spot size produced a positional and elevational resolution on the order 0.1 to 0.3 mm. This scanner can be used to digitize surfaces at fine grid spacings and the detailed surface topography can then be used to study surface boundary processes such as soil erosion.