bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Winter and Summer Windbreaks on Soil Water Gain and Spring Wheat Yield
Authors: Frank A. B. , Willis W. O. 
Published: July 2010

AbstractField windbreaks have been planted primarily for soil erosion control, but they also affect the growth and yield of nearby crops by modifying the crop's microclimate (summer effects) or by trapping snow for soil water gain (winter effects). The purpose of this study was to partition and determine the summer and winter effects of noncompetitive windbreaks using ‘Waldron’ spring wheat (Triticum aestivum L.) as a test crop.We erected 2.3‐m high by 32‐m long slat‐fence barriers in an eastwest direction during winter (W+S‐), summer (W‐S+), both winter and summer (W+S+), or not at all (W‐S‐). The top and bottom halves of each barrier were 42 and 21% dense, respectively. Three years of the 6‐year study were classified as wet years and three were dry years based on total available water (available soil water at seeding plus seeding‐to‐harvest precipitation) for the crop. Snow depth, soil water gain over winter, crop water use, wheat yield, and plant height were measured at 2H (H = barrier height) units to 6H north and 10H south of the barriers. Snow trapped by the barriers ranged from 1.2 m deep 5H south of the barrier in 1975 to no measurable snow in 1973. Soil‐water gain from snowmelt was greatest 5H south of the barrier and averaged 1.9 cm more over the test area for W+S+ and W+S‐ as compared with W‐S+ and W‐S‐ treatments. Average wheat yields for the 3 wet years were the same for all treatments, but for the 3 dry years the W+S+ and W+S‐ treatments increased yields by 3.2 and 2.1 quintal/ha, respectively, as compared with the W‐S‐ treatment. The summer‐only barrier (W‐S+) had no measurable effect on wheat yields. Wheat yields during the dry years were maximum at 5H south of the barrier, which coincided with maximum snow depths and overwinter soil water gains.Results of this study showed that grain yield increases obtained adjacent to noncompetitive barriers were mostly due to increased overwinter soil water accretion resulting from snow catch (winter effects) and not microclimate modification (summer effects).
Influence of Row Spacing of Grain Sorghum on Ground Cover, Runoff, and Erosion
Authors: Adams J. E. , Richardson C. W. , Burnett E. 
Published: July 2010

AbstractA study was begun at Temple, Texas, in 1972 to assess the effect of narrow (50‐cm) and conventional (100‐cm) row spacing of grain sorghum [Sorghum bicolor (L.) Moench] on runoff and erosion from field‐sized areas. Sorghum in narrow rows established a more complete plant canopy earlier than sorghum with conventional row spacing and provided more ground cover for much of the growing season. In 1973, runoff was 45% less and soil loss was 39% less from narrow‐row grain sorghum than from sorghum with conventional row spacing. Narrow‐row spacing of sorghum increased ground cover significantly (5% level) 35 days after emergence in 1974. Canopy cover was at maximum by 63 days after seedling emergence and provided a ground cover of 46 and 81% for sorghum with 100‐ and 50‐cm row spacing, respectively.
Nutrient Flux in Litter and Surface Soil after Nitrogen and Phosphorus Fertilization
Authors: Kelly J. M. , Henderson G. S. 
Published: July 2010

AbstractThe effect of urea and concentrated superphosphate additions on the movement of N, P, K, and Ca from the litter and top 10 cm of the mineral soil via the soil solution was evaluated in an upland oak forest using tension lysimeters. The range in total flux values for each element over the study period were: N 24.8 to 1145.3; P 2.0 to 633.3; Ca 70.6 to 553.1; and K 49.5 to 94.0 kg/ha in response to various combinations of N and P fertilizer addition at levels of 0, 550, and 1100 kg/ha N and 0, 275, and 550 kg/ha P. Nitrogen fertilizer addition significantly increased the flux of N and K while reducing the flux of P and Ca. Phosphorus fertilizer addition significantly increased N, P Ca, and K fluxes. Solubilization of organic matter and the formation of insoluble calcium ammonium phosphate were important processes regulating the flux of N, P, Ca and K.
Evaluation of Conceptual Models for Describing Nonequilibrium Adsorption‐Desorption of Pesticides During Steady‐flow in Soils
Authors: Rao P. S. C. , Davidson J. M. , Jessup R. E. , Selim H. M. 
Published: July 2010

AbstractBreakthrough curves (BTC) from miscible displacement of two pesticides through three soils were measured for two input concentrations of each pesticide. These BTC data were used to evaluate two conceptual models for describing the nonequilibrium adsorption‐desorption of pesticides in soils under steady‐state water flow conditions. In both models, adsorption on one group of sites was assumed to be instantaneous, while the rate of adsorption on the second group of sites followed either nonlinear reversible kinetics (Model I) or was a diffusion‐controlled process (Model II). Parameters in both models were estimated by curve‐fitting model predictions to one set of measured BTC data using a nonlinear least‐squares optimization procedure. These parameter values were then used to verify the conceptual models by comparing simulated and measured BTC for a different input concentration. A different set of model parameters were required to describe the BTC data for each input concentration for the same soil‐pesticide combination. The measured 3H2O BTC for all three soils were symmetrical in shape with no apparent tailing. Evaluation of Model I and II using these BTC suggested that the mobile‐immobile water concept may not be applicable to the three soils used in this study.
Reactions of Ammonium Ortho‐ and Polyphosphate Fertilizers in Soil: II. Hydrolysis and Reactions with Soil
Authors: Khasawneh F. E. , Hashimoto I. , Sample E. C. 
Published: July 2010

AbstractReactions of P from triammonium pyrophosphate (TPP), ammonium polyphosphate (APP), and diammonium phosphate (DAP) were investigated in replicated columns of Hartsells fsl soil (a Typic Hapludult) at a moisture content of 19% that were incubated for 1, 2, or 4 weeks at 25°C. The diffusive movement of P was accompanied by two major reactions: (i) hydrolysis of pyro‐ and polyphosphates to the orthophosphate form; and (ii) precipitation reaction of all phosphatic anions with soil. Hydrolysis of the water‐soluble fraction of the condensed forms of P was rapid, with a half life that ranged from 9 to 16 days. Hydrolysis of the water‐insoluble fractions was severely retarded by their insolubility and could not be measured in 4 weeks. Because the rate of hydrolysis was faster than that of diffusion, mobility of the pyro‐ and polphosphates occurred largely in the orthophophate form and accounted for the similarity of P movement among the three sources. The precipitation reactions of pyro‐ and polyphosphate were virtually complete in the 1st week, were irreversible and localized within well‐defined zones, and accounted for nearly one‐fourth of the added P. Precipitation of orthophosphates increased considerably with time and higher concentrations of water‐soluble orthophosphate, and decreased by pyro‐ and polyphosphate competing for the same precipitating agents. Furthermore, orthosphate precipitation was dispersed rather than localized and showed signs of reversibility. The total water‐insoluble fractions after 4 weeks accounted for 58, 63, and 45% of added P from TPP, APP, and DAP, respectively.
Use of Inductively‐coupled Plasma Spectrometry for the Simultaneous Determination of Macro‐ and Micronutrients in NH4HCO3‐DTPA Extracts of Soils
Authors: Soltanpour P. N. , Workman S. M. , Schwab A. P. 
Published: July 2010

AbstractTwenty‐six soils were extracted with 1M NH4HCO3‐. 0.005M DTPA solution (Soltanpour and Schwab, 1977). Inductively‐coupled plasma optical emission spectrometry (ICP‐OES) was used to simultaneously determine P, K, Zn, Fe, Cu, and Mn in the extracts. These analytical results were compared with those obtained with a colorimetric method for P and flame atomic absorption spectrometry (AAS) for the cations. It was necessary to change the carbonate‐bicarbonate matrix (1M) to a more soluble matrix in order to prevent formation of crystals and clogging at the capillary tip. This was achieved by a 1:5 dilution with 0.5N HNO3 followed by shaking for 10 min. Results from the ICP‐OES and the flame AAS methods were comparable. Analysis of P by ICP‐OES gave larger values than analysis by a colorimetric method due to presence of organic P in the extracts.
Chamber Systems for Measuring Nitrous Oxide Emission from Soils in the Field
Authors: Denmead O. T. 
Published: July 2010

AbstractRecent concern over N2O losses from soils has highlighted the need for new techniques for measuring N2O exchange in the field. Two systems are described, in which nondispersive infrared gas analysis is used to measure the change in N2O concentration of air passing through a cylindrical chamber driven 0.1 m into the ground. When interfering gases are removed from the air stream, the infrared analyzer has a resolution of ± 12 ppb N2O.In one system, air circulates in a closed loop between the chamber air space and the gas analyzer; in the other, open system, outside air is drawn continuously through the chamber space and its N2O enrichment or depletion measured.Two operational problems (common to many emission chambers) were encountered: the development of a low pressure in the chamber when air is withdrawn, which induces a mass flow of N2O from the soil in addition to the diffusive flow; and a readjustment of the N2O concentration in the soil air whenever the N2O concentration in the chamber air changes from ambient. These can lead to incorrect estimates of the flux. The former problem was overcome by chamber design. The latter appeared to be insurmountable in the closed system, but could be reduced to acceptable proportions in the open system by choice of air flow rate.The open system permits relatively rapid equilibration, automatic and continuous operation, a discrimination less than 2 ng N m−2 sec−1, and the maintenance of environmental conditions within the chamber close to those in the field.
The Release of Sulfate from Soil‐Applied Basaluminite and Alunite
Authors: Wolt J. D. , Adams Fred 
Published: July 2010

AbstractRelease of SO4 from synthetic basaluminite and alunite was measured by plant uptake after mixing various rates of these compounds with Marvyn loamy sand at pH 6.5. The fraction of SO4 released from basaluminite was about one‐half that from gypsum, according to S uptake by cotton plants. Alunite released very little SO4. Release of SO4 by basaluminite in soil supports the thesis that SO4 retention and desorption in acid soils can be explained in part by solubility of Al‐hydroxysulfates.
Salinity Profiles and Leaching Fractions for Slowly Permeable Irrigated Field Soils
Authors: Lonkerd W. E. , Ehlig C. F. , Donovan T. J. 
Published: July 2010

AbstractThe salinity status of four slowly permeable irrigated soils was measured under commercial field conditions to determine the magnitude and variability of actual leaching fractions. Soil cores were taken in 30‐cm increments to a 150‐cm depth. Assuming a desirable leaching fraction of 15 to 20% for lettuce (Lactuca sativa L.), and 5 to 10% for alfalfa (Medicago sativa L.), cotton (Gossypium hirsutum L.), sugarbeet (Beta vulgaris L.), and wheat (Triticum aestivum L. em Thell.), for nearly all soil‐crop combinations, leaching fractions ranged from insufficient to excessive. Median leaching fractions were excessive in Holtville and Indio soils planted to lettuce, sugarbeet, and wheat and insufficient or marginal in Imperial and Meloland soils planted to all crops.
Ammonia Volatilization from Surface Applications of Urea in the Field and Laboratory
Authors: Hargrove W. L. , Kissel D. E. 
Published: July 2010

AbstractFew attempts have been made to directly measure ammonia losses from surface applications of urea under field conditions. The objective of this research was to measure NH3 volatilized from urea in the field and to compare these losses to (i) losses measured in the laboratory, and (ii) losses estimated by crop response in the field. Direct field measurements were made using an automated apparatus designed to collect NH3 lost without significantly altering environmental conditions on the treated area. Laboratory measurements were made using an apparatus similar to systems described previously by other workers. Ammonia losses were estimated from crop response in the field by measuring N uptake by Coastal bermudagrass (Cynodon dactylon L.).Losses of NH3 in the field measured directly were small (0 to 9% of the applied N) compared to those obtained in the laboratory (13 to 31% of the applied N) and those estimated in the first year of the N uptake study (0 to 39% of the applied N). However, in the second year of the field plot study, N uptake by forage from several urea fertilizer treatments was greater than from Ca(NO3)2. When the results were combined for both years, N uptake by forage was similar from Ca(NO3)2 and urea treatments. Considering the small ammonia losses measured directly in the field, differences in crop response between urea and Ca(NO3)2 may have been due to some factor other than NH3 volatilization.Results indicate that losses of N by NH3 volatilization under field conditions may not be as severe as previously thought, at least under the soil and environmental conditions of this study. Results also demonstrate the importance of directly measuring NH3 losses in the field.
Irrigation System Effects on Applied Fertilizer Nitrogen Movement in Soil
Authors: Onken Arthur B. , Wendt C. W. , Wilke O. C. , Hargrove R. S. , Bausch Walter , Barnes Larry 
Published: July 2010

AbstractMovement of unused fertilizer nitrate‐nitrogen (NO3‐‐N into shallow underground water strata by way of irrigation return flows has become a concern as irrigation has increased. Previous research has been largely conducted with furrow and sprinkler irrigation systems in areas of low rainfall and in many cases in the absence of a growing crop. We studied, directly in the field, the effects of furrow, sprinkler, and subirrigation on the movement of fertilizer NO3‐‐N in a supplementally irrigated area in the presence of sweet corn (Zea mays L.).Sodium nitrate enriched with 15N was band applied below the surface at rates of 124 and 105 kg of N/ha in 1973 and 1974, respectively. Soil samples were periodically taken in 30‐cm vertical increments through each fertilizer band, the center of the bed and beneath each furrow. Under sprinkler irrigation the fertilizer bands tended to move down with somewhat less lateral movement close to the soil surface than with the other systems. Also, movement out of the surface 30 cm was faster than for the other irrigation systems. Under furrow irrigation the fertilizer tended to move toward the center of the bed and then moved downward. With subirrigation the fertilizer moved upward and outward toward the furrows and then moved downward. The fertilizer remained in the upper 30 cm of soil longest with subirrigation.
Salt Effects on the Hydraulic Conductivity of a Sandy Soil
Authors: Pupisky H. , Shainberg I. 
Published: July 2010

AbstractThe changes in the hydraulic conductivity of a Red Brown sandy soil as a function of the concentration and SAR of the percolating solutions were measured. Also, the changes in the hydraulic heads along the soil column and analysis of the salt and clay concentrations in the effluent solutions were recorded. The data show that at high ESP's and at salt concentration above 0.01N, swelling of the clay is the main mechanism responsible for hydraulic conductivity decrease. At low ESP and very dilute soil solutions, dispersion and clay migration into the conducting pores are the main mechanisms responsible for plugging the soil pores. Dispersion of the clay particles is possible only when the concentration of the soil solution drops below a threshold concentration at which the clay platelets flocculate. Dispersion of the clay may lead also to an increase in hydraulic conductivity when a sandy soil is leached with distilled water.
Adsorption of Phosphate by Hydroxy‐Aluminum Species on a Cation Exchange Resin
Authors: Robarge W. P. , Corey R. B. 
Published: July 2010

AbstractA study was conducted to provide a possible explanation for the reported decrease in the concentration of P in soil solutions with increasing pH and/or ionic strength. The assumption was made that P in solution decreases because of the formation of a new P‐adsorbing surface, the source of which would be exchangeable Al3+. An Al‐saturated resin was used as a model of an acid soil to study the effects of pH, charge and/or concentration of associated cation on the concentration of P in solution when the P‐adsorbing complex is affixed to a negatively charged surface. The hydroxy‐Al species formed by adding base was found to be the primary P‐adsorbing surface. The OH/Al molar ratio of the hydroxy‐Al species formed remained nearly constant with addition of base (2.0 to 2.1:1 in the presence of Ca(ClO4)2; 2.4:1 in the presence of NaClO4; µ = 0.003) until all the Al3+ present had been converted to the hydroxy‐Al form. The pH of formation of the hydroxy‐Al species was a function of µ and neutral salt cation.Phosphate was added at Al/P molar ratios of 12:1 or 6:1 in the presence of Ca(ClO4)2 or NaClO4 of equal ionic strengths (µ = 0.0003 or 0.003). The hydroxy‐Al species demonstrated a marked capacity to adsorb P. At an Al/P molar ratio of 2.0:1 (Ca(ClO4)2; µ = 0.003) the equilibrium concentration of P was < 0.2 mg/l. As % neutralization of exchangeable Al3+ increased, at constant total P concentrations, P in solution initially decreased, passed through a minimum, and then increased. The pH of minimum P in solution corresponds to the point where increased adsorption due to increasing adsorbing surface is balanced by increasing competition from hydroxyl ions for adsorption sites. Exchangeable Al3+ did not react with added P until the Al/P ratio of the hydroxy‐Al species equalled or became less than 2.0:1.The effects of µ and pH on P adsorption in the Al‐resin system are similar to many results reported in the literature for soil systems. Our studies suggest that the often observed correlation between exchangeable Al3+ and P fixation by soils is due to the relationship between Al3+ and the formation of the hydroxy‐Al species, unless the P addition rate is high enough to favor the precipitation of an aluminum‐phosphate compound. Hydroxy‐Al species formed by liming acid soils to above the pH at which all exchangeable Al3+ is converted to nonexchangeable forms appear to be stable enough to affect the concentration of P in solution over the short‐term, but may be unstable with respect to gibbsite or other Al minerals over long periods of time.
Nodulation of Trifolium subterraneum L. by Introduced Rhizobia in Southwest Oregon Soils
Authors: Hagedorn Charles 
Published: July 2010

AbstractThe establishment of Trifolium subterraneum L. in response to inoculation and fertilization treatments was determined at five field sites in southwest Oregon. Both strains of Rhizobium trifolii (TA1 and C6) were capable of successful nolulation of subclover (c. v. Mt. Barker) at all sites although differences in performance of the strains occurred at three locations. Fertilization (P, S, and Mo) significantly increased the overall nodulation of the plants as well as the proportion of nodules occupied by the inoculum strains. Both plant dry weights and total N levels reflected an additive effect of inoculation and fertilization. Results indicated that subclover appeared to be a suitable crop for hill pastures in western Oregon and, with adequate fertilization and a suitable inoculum, the subclover and the amended rhizobia can become established and productive during the first growing season.
Mottling and Iron Distribution in a Glossoboralf‐Haplaquoll Hydrosequence on a Glacial Moraine in Northwestern Wisconsin
Authors: Richardson J. L. , Hole F. D. 
Published: July 2010

AbstractDistribution of iron oxide and forms of mottling and cutans under various moisture regimes were studied in a Woodfordian glacial moraine landscape. Hydrosequence members were observed and sampled along two transects in adjacent first‐order drainage basins. Considerable iron had been translocated out of the A horizon and either into the B horizon or out of the solum, in all pedons studied. Mottle development followed an expected systematic sequence from none at well‐drained (WD) sites, where unsaturated movement of water predominates; to considerable at somewhat poorly drained (SPD) sites, where saturated flow occurs frequently and where the dry‐wet cycle is characteristic; to few at very poorly drained (VPD) sites where gleying has been favored by stagnant water conditions in wet seasons. At WD sites mottles were either absent or of low chroma both in the interiors and on the faces of peds. At SPD sites mottles were of low chroma on ped faces and of high chroma inside peds, and Fe‐Me concretions were relatively abundant. At VPD sites neutral gray hues predominated both inside peds and on surfaces of macrospores, and there were only a few iron concretions or, at wettest sites, “pipestems.” Changes in distribution of iron extractable by aqua regia, dithionite and oxalate characterized the degree of crystallinity of iron compounds in the sequence. Iron oxides were most crystalline at WD sites where they tended to concentrate in the clay fraction. Iron oxides were concentrated in sand‐size concretions at SPD sites.
Carolina Bays on the Eastern Shore of Virginia
Authors: Bliley D. J. , Pettry D. E. 
Published: July 2010

AbstractCarolina bays were analyzed on the Eastern Shore of Virginia utilizing infrared imagery and pedologic techniques. Over 160 bays were delineated thus indicating they are major landforms in the area. Bays differed from those reported in other regions by being less elliptical, more westerly oriented, and lacking well‐developed rims in any specific quadrant. Bay location and size are apparently controlled by landscape and sandy parent materials as evidenced by association with less distinct natural depressions with similar orientation as the related geomorphic urface. Soils on bays of recent surfaces have weaker profile development compared to Pleistocene upland bays. More than one period of bay formation is suggested by differential pedogenic development and geomorphic positions. Data indicate Carolina bays were formed by the alteration of poorly drained areas on undissected Coastal Plain interfluves. Wind and waves are suggested as factors in bay formation based on well‐sorted sands of elevated rims, “dune‐like” character, and silt content of possible aeolian origin.