bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting Soil Temperatures to Indicate Winter Wheat Mortality
Authors: Larsen J. K. , Brun L. J. , Enz J. W. , Cox D. J. 
Published: July 2010

AbstractTillage effects on soil temperature that affect winter wheat survival (Triticum aestivum L.) were investigated from 1981 to 1985 at Fargo, ND. Tillage systems used all 4 yr were reduced (disked) and no‐till tall stubble (seeding directly into 20‐cm standing stubble). Conventional tillage (plow, disk, and harrow) in 1981–82 and 1982–83, and no‐till short stubble (seeding directly into 5‐cm stubble) in 1983–84 and 1984–85 comprised the third tillage system used for comparisons. Survival of winter wheat in the no‐till tall stubble system was near 100% in each of the 4 yr, while in 2 of the 4 yr, survival was 50% or less in the other tillage systems. Differences in survival were attributed to warmer soil temperatures in the tall stubble system. Hourly soil and air temperature measurements and snow depth were used to develop a statistical model that predicts daily minimum crown depth (3 cm) soil temperatures (R2 = 0.92). An independent set of data was used to test the model; soil temperatures within the range considered critical for winter wheat were predicted to an accuracy of 1 °C. Predicted crown depth soil temperature may be used to indicate winter wheat mortality.
Aggregation and Aggregate Stability in Forest and Range Soils
Authors: Strickland T. C. , Kerle E. A. , Sollins P. , Schimel D. S. 
Published: July 2010

AbstractA simple method for measuring aggregation and aggregate stability across soils of widely varying structure and texture is presented. The method uses standard techniques of particle‐size analysis to measure yield of fine particles (<26‐µm estimated spherical diam.) after three types of dispersion treatments: shaking in water or in sodium oxalate (Ox), and sonication in sodium pyrophosphate (PPi). PPi sonication, which provided maximum dispersion, served as our benchmark; it was substantially more effective than the commonly used stirring in hexametaphosphate. Aggregation was then calculated as yield of fines after PPi sonication minus yield of fines after the water shake, the minimum dispersion treatment. Aggregate stability was measured by comparing yield of fines after the Ox shake, the mild dispersion treatment, with that after the water shake; aggregate instability was then calculated. The five soils studied varied markedly in both aggregation and aggregate stability, suggesting that mechanisms of aggregate stabilization differ markedly across soil types. Despite these differences, our method of quantifying mild dispersion by shaking with Ox, which should have negligible effect on subsequent microbiological studies, relative to complete dispersion by PPi sonication should be consistent and applicable over a reasonably wide range of soil types.
Lodgepole Pine Fertilization Screening Trials: Four‐year Growth Response Following Initial Predictions
Authors: Weetman G. F. , Fournier R. M. , Schnorbus E. 
Published: July 2010

AbstractThe use of fertilizer screening trials was examined to determine if the pattern of 4‐yr basal area (BA) increment response by treatment agreed with the predictions based on first season needle weight response. Screening trials can diagnose stand nutritional status and subsequent response. Nitrogen, P and K in various combinations were applied to 17 lodgepole pine (Pinus contorta var. latifolia Engelm.) stands in the interior of British Columbia, Canada. Of these, 14 had been precommercially thinned. Remeasurement of 15 stands after 4 yr showed that 50 to 150 kg N ha−1 produced significant growth responses in many stands. Nitrogen applied at rates of 50, 100, and 150 kg ha−1 increased BA growth of individual trees by an average of 27, 41, and 48% over the control, respectively. Adding P at 50 kg ha−1 significantly improved BA growth in only two stands, while the effect of K was not significant. Graphical diagnoses of shifts in unit fascicle weight and foliar concentrations and contents in the first growing season following fertilization generally corresponded with subsequent 4‐yr BA response in 11 of the 15 installations. Stands responsive to N fertilization were weakly responsive to thinning. Nonresponsive stands reacted to thinning, presumably because N was not limiting growth. The best fit of multiple regression analyses between basal area response and stand factors yielded an R2 of 0.57, with needle weight and foliar N and P levels as important variables.
Nitrogen Use Efficiency and Nitrogen‐15 Balances in Broadcast‐seeded Flooded and Transplanted Rice
Authors: De Datta S. K. , Samson M. I. , Kai‐Rong Wang , Buresh R. J. 
Published: July 2010

AbstractIncreased irrigated areas, availability of short‐duration modern rices (Oryza sativa L.) and cost‐efficient herbicides, and high labor cost have motivated Asian farmers to shift from transplanting to broadcast seeding in flooded rice. Information on fate of N in broad‐cast‐seeded flooded rice (BSFR), however, in Asia is limited. Thus, two field experiments were conducted on a Vertic Tropaquept to evaluate efficient N management practices in BSFR using 15N‐labeled fertilizers and to compare the performance of BSFR and transplanted rice (TPR) under similar N management practices. For urea, basal deep placement (DP) as supergranules and a three‐split application gave the lowest mean 15N losses (4 and 11%, respectively) and highest mean grain yields (6.9 and 7.1 Mg ha−1, respectively) for BSFR. Mean 15N losses from urea applied to BSFR were 20 and 18%, respectively, for the researchers' split (RS) (two‐thirds basally incorporated into mud plus one‐third at 5 to 7 d before panicle initiation) and the farmers' split (FS) (one‐half topdressed into water at 15 d and one‐half topdressed at 10 d after panicle initiation). The agronomic efficiency (kg grain per kg applied N) for 40 kg applied urea‐N was 57, 43, and 28 with DP, RS, and FS, respectively. Under the same urea management practices, the mean plant recovery of 15N was greater for BSFR (47%) than for TPR (37%). This resulted in lower 15N loss for BSFR (20%) than for TPR (32%). However, total plant N accumulation was similar for BSFR (96 kg ha−1) and TPR (95 kg ha−1), and mean grain yields over the two experiments were not different (P = 0.05) between BSFR and TPR. Transplanted rice produced 10 kg more grain per kilogram of applied N than did BSFR, in part because mean grain yield in the absence of applied N was 0.3 Mg ha−1 lower with TPR. Results suggest that considerable potential exists to increase N use efficiency and grain yield in BSFR by manipulating N fertilizer and water management practices.
Effect of Two Urease Inhibitors on Floodwater Ammonia Following Urea Application to Lowland Rice
Authors: Buresh R. J. , De Datta S. K. , Padilla J. L. , Samson M. I. 
Published: July 2010

AbstractOne proposed strategy for overcoming N loss by ammonia volatilization from urea applied to flooded rice (Oryza sativa L.) fields is to amend urea with a urease inhibitor. The inhibitor, in theory, would delay urea hydrolysis and thereby prevent the buildup of ammonia in the floodwater. Field studies were conducted at two locations in the Philippines to determine the effect of two urease inhibitors, phenyl phosphorodiamidate (PPD) and N‐(n‐butyl) thiophosphoric triamide (NBPT), on the vapor pressure of ammonia (pNH3) following application of urea to floodwater. Three rates of urea were applied two‐thirds dosage at 18 d after transplanting (DT) and one‐third dosage at 5 to 10 d after panicle initiation (DAPI). The amendment of urea with either PPD or NBPT retarded the disappearance of urea from floodwater and reduced the buildup of floodwater ammoniacal‐N. NBPT generally matched or exceeded PPD in ability to reduce pNH3 at each N rate and timing for both locations. Whereas PPD only delayed the buildup in pNH3, particularly at higher N rates, NBPT effectively prevented a buildup in pNH3. For the 10 d following the first N application, NBPT reduced the mean pNH3 at 1400 h by 95, 96, and 98% for 23, 47, and 93 kg N ha−1, respectively, at one location. The corresponding reductions with PPD were 82, 54, and 25%, respectively. At the other location, NBPT reduced the mean pNH3 following the first N application by 97, 77, and 79% for 23, 47, and 93 kg N ha−1, respectively. The corresponding reductions with PPD were 79, 77, and 28%, respectively. The results suggested that urease inhibitors can effectively reduce ammonia loss from urea broadcast into the floodwater of rice fields.
Effect of Fertilizer Phosphorus Particle Size on Phosphorus Fertilizer Efficiency
Authors: Sander D. H. , Eghball B. 
Published: July 2010

AbstractFive field experiments were conducted over 3 yr (1983–1985) to evaluate the effect of P fertilizer particle size on winter wheat (Triticum aestivum L.) yield and P uptake. In 1983, an introductory experiment indicated that the P fertilizer particle size could greatly affect fertilizer P effectiveness. Studies in 1984 and 1985 confirmed these observations. In these studies ammonium polyphosphate (11‐24‐0, N‐P‐K), at particle weights of 0.00019, 0.0009, 0.025, 0.93, and 22 mg were applied at P rates of 8.4, 16.8, and 25.2 kg P ha−1 on four different soils. Wheat grain yields were increased significantly by applied P on all four soils. Grain yields were affected by P fertilizer particle size only, however, on the Ascalon and Holdrege soils (Aridic and Typic Argiustoll, respectively) where yield increases from applied P were greatest. Maximum grain yield occurred at approximately the intermediate particle size studied (0.025 mg), although optimum particle size was dependent on P rate. As the P rate increased, particle size became less of a factor influencing fertilizer effectiveness. Wheat grain yield at the 8.4‐kg ha−1 P rate was 0.31 Mg ha −1 less for the 22‐mg particle compared to the 0.025 mg particle. Calculations indicated that the 22‐mg fertilizer particles had an average distance of 2.8 cm from one another in the band area, compared to 0.003 cm or a continuous band for the 0.025‐mg particles. Phosphorus uptake and other yield components generally paralleled the results with grain yield. Fertilizer P efficiency in terms of fertilizer P uptake, reached a maximum of 47% with a particle size of 0.15 mg and an application rate of 8.4 kg P ha−1 on the Holdrege soil. This was a 20% increase in efficiency over a normal farm fertilizer size of 20‐mg particle 1. While optimum fertilizer size probably ranges from 0.025 to 1 mg per particle, the optimum size in these experiments in terms of both yield and fertilizer efficiency was generally less than the 20‐mg particle size reported for farm fertilizers. Results indicate that greater root proliferation in continuous P bands may be responsible for an increase in fertilizer P uptake and efficiency compared to discontinuous P bands.
A Rapid Method of Soil Carbonate Analysis Using Gas Chromatography
Authors: Amundson Ronald G. , Trask Joanne , Pendall Elise 
Published: July 2010

AbstractA rapid and sensitive method of soil carbonate analysis, utilizing gas chromatography, is presented. The analysis of soil samples by gas chromatography and the Chittick methods produced comparable results (r = 0.96, slope = 1.11). However, the gas chromatograph method was much more rapid. There was also a linear relationship between the results of soils analyzed by both the gas chromatograph and Hg manometer methods (r = 0.99). The gas chromatograph underestimated CaCO3 contents at low concentrations, however, and overestimated it at high concentrations relative to the manometer method. The gas chromatograph method was the most sensitive and had the lowest possible detection limit (0.008 mg CaCO3) of the methods compared. The results of the study indicate that the gas chromatograph method is much more rapid than previously reported chromatography methods and has the potential to be used for the rapid analysis of samples low in CaCO3.
Temporal Persistence of Spatial Patterns of Soil Water Content in the Tilled Layer Under a Corn Crop
Authors: van Wesenbeeck I. J. , Kachanoski R. G. , Rolston D. E. 
Published: July 2010

AbstractThe temporal persistence of the spatial pattern of soil water storage (0∼0.2 m) under a corn (Zea mays L.) canopy during drying and recharge periods were examined using spatial coherency analysis and transfer function theory. The corn crop caused both drying and recharge to occur at very specific scales, equal to the crop row spacing. The calculated transfer function, or time varying spectrum showed the scale at which the change in the spatial pattern was occurring and quantified the increase or decrease in variance at that scale. The spatial pattern of the drying coefficients, a measure of the relative drying rate, also varied systematically with significantly higher drying rates in the row area developing as the growing season progressed. The increase in relative drying rate in the row area caused the spatial pattern of drying to change at a scale equal to the crop row spacing. The calculated transfer function of the drying coefficients over the growing season indicated a steady increase in variance at that same scale, while the variance at other scales did not change significantly. An equation is developed relating the transfer function of soil water content in space to the spectrum of the process causing the change in the spatial domain.
An Investigation of Iron(III)‐Fulvic Acid Complexes by Mössbauer Spectroscopy and Chemical Methods
Authors: Kodama H. , Schnitzer M. , Murad E. 
Published: July 2010

AbstractThree iron(III)‐fulvic acid (FA) “complexes” were prepared in the laboratory. One of these was doped 50% with 57Fe and contained 1.54% total Fe. The other two “complexes” contained 0.80 and 4.70% Fe, respectively. At room temperature, Mössbauer spectra of the Fe(57Fe)‐FA “complex” consisted of a paramagnetic doublet. The isomer shift (δ/Fe) was 0.30 mms−1 and the quadrupole splitting (ΔEQ) was 0.75 mms−1, typical of ferric iron. At 78 K the spectrum showed a magnetic component superimposed upon the quadrupole doublet. In the spectrum recorded at 4.2 K the magnetic contribution increased. An analysis of the Mössbauer data suggests that Fe(III) in laboratory‐prepared Fe(III)‐FA “complexes” occurs partly in the form of organic complexes and partly as inorganic species. Support for this view also comes from ESR data published in the literature. A study of the resistance of Fe in the “complexes” to base hydrolysis, showed that iron was associated with the FA by at least two, possibly three, different mechanisms and that the interaction products exhibited differing chemical stabilities.
Soil Microbial Biomass and Organic Component Alterations in a No‐Tillage Chronosequence
Authors: Staley T. E. , Edwards W. M. , Owens L. B. , Scott C. L. 
Published: July 2010

AbstractA no‐tillage (NT) chronosequence that had been continuously cropped to maize (Zea mays L.) for 0, 1, 2, 4, 7, 9, 15, or 20 yr on a Westmoreland silt loam (fine‐loamy, mixed, mesic Ultic Hapludalf) was examined for differences in microbial biomass, and soil organic C, N, P, and S. In the plowzone of the NT sites, biomass‐C, total C (TC), soluble organic C (SOC), total Kjeldahl N (TKN), organic P (OP), and organic S (OS) levels were generally greater in the soil surface (0 to 7.5 cm) layers than in the 7.5‐ to 15‐cm layers. In contrast, biomass‐C under conventional tillage (CT or 0‐yr NT site) in the soil surface layer was ∼50% of that in the 7.5‐ to 15‐cm layer, whereas levels of the organic components were nearly identical. Biomass‐C and organic component levels in the soil surface layers under NT were from 27 to 83% greater than those under CT. Opposite tillage method effects on these properties were usually found for deeper soil layers. Soil organic components, but not biomass‐C, were significantly (p ≤ 0.05) related to years under NT in the soil surface layer. Only biomass‐C was significantly (p ≤ 0.10) related to years under NT in deeper soil layers. When just “typical (i.e., nonmanured, moderate N‐rate)” sites were included in the regression models, only biomass‐C and SOC reservoir contents (total to 45 cm) varied significantly (p ≤ 0.10) with years under NT. Soil biomass‐C reached a maximum (786 kg·ha furrow‐slice−1) in the soil surface layer after only 1 yr under NT, approaching a level nearly equivalent to that under an improved pasture, then equilibrated in about 10 yr to a level approximately 30% greater than that under CT. These observations suggest that continual NT induces a predictable dynamic in soil biomass‐C, but not soil organic components, that is generally insensitive to a range of management differences. As a consequence, management practices designed to improve nutrient use‐efficiency, especially by controlling microbial mineralization/immobilization activity, should not only take into consideration tillage method but years under the tillage method as well.
Net Mineralization of Carbon and Nitrogen Under Aerobic and Anaerobic Conditions
Authors: Gale P. M. , Gilmour J. T. 
Published: July 2010

AbstractA study was conducted to compare the net C and net N mineralized during the decomposition of alfalfa (Medicago sativa L.) under aerobic and anaerobic conditions. Dried and ground alfalfa was mixed with soil at a rate of 5 g kg−1 and incubated either aerobically at optimum water in a CO2—free atmosphere or anaerobically (flooded) in an N2 atmosphere. The decomposition process was followed by measuring the CO2 and CH4 evolved, water soluble organic C, and inorganic N. Aerobic C mineralization was best described using CO2 evolution as a first‐order kinetic process. Three distinct phases of decomposition were observed (rapid, intermediate, and slow) with rate constants (k) of 0.123, 0.059, and 0.0095 d−1, respectively. Under anaerobic conditions, CO2 evolution remained fairly constant throughout the experiment. The decomposition rate constant for anaerobic CO2 evolution was 0.006 d−1. Carbon mineralization under anaerobic conditions was best described as the sum of CO2 and CH4 evolved plus the water soluble organic C produced. This treatment resulted in three distinct phases of anaerobic decomposition. The C mineralization rate constants for the rapid and intermediate phases were 0.118 and 0.024 d−1, respectively. No rate constant was determined for the slow phase. A computer simulation model was used to estimate the C and N mineralized under both aerobic and anaerobic conditions. The linear relationship between the predicted and observed mineralization was evaluated. For C mineralization the slope was 1.1 and that of N mineralization was 1.0, with R2 values of 0.961 and 0.946, respectively.
Comparison of Total Nitrogen by Four Procedures and Sequential Determination of Exchangeable Ammonium, Organic Nitrogen, and Fixed Ammonium in Soil
Authors: Antisari Livia Vittori , Sequi Paolo 
Published: July 2010

AbstractEight soils were analyzed for total N by: (i) steam distillation of NH3 yielded after conventional H2SO4 digestion, (ii) HF‐H2SO4 digestion, (iii) HF‐HCl treatment in a microwave system, or (iv) a CHN analyzer. Comparison of results showed that the customary Kjeldahl methods underestimate total N in soils. After determination of exchangeable NH4, soil organic matter was destroyed by treatment with a reagent composed of hydrogen peroxide plus pyrophosphate plus NaCl to prevent swelling of clays, buffered at pH 5 to avoid loss of NH3. Organic N was calculated as the sum of NH4 and NO3 determined in the resulting solution produced during organic matter oxidation. Soil residues were analyzed for fixed NH4 using the three above mentioned procedures. It was deduced that underestimation of total N given by the customary Kjeldahl method depends on inefficiencies of acid digestion in releasing NH4 trapped in clay lattices. Values for total N calculated from the sum of exchangeable NH4, organic N, and fixed NH4 are fairly consistent with those determined directly.
Evaluation of a Method to Predict Nitrogen Mineralized from Soil Organic Matter Under Field Conditions
Authors: Cabrera M. L. , Kissel D. E. 
Published: July 2010

AbstractMethods to estimate the amount of N mineralized from soil organic matter are needed for accurate fertilizer recommendations. We conducted laboratory and field studies to evaluate the method of Stanford and Smith for predicting N mineralized under field conditions. Soil samples were incubated to determine their N mineralization potentials and first‐order rate constants of mineralization. To predict N mineralized in the field, the rate constants of mineralization were adjusted by soil temperature, and the amount of N mineralized predicted with the N mineralization potentials and adjusted rate constants were further adjusted by soil water content. Nitrogen mineralized in the field was measured in sorghum [Sorghum bicolor (L.) Moench] plots established on Haynie (coarse‐silty, mixed, calcareous, mesic Mollic Udifluvent), Kahola (fine‐silty, mixed, mesic Cumulic Hapludoll), and Richfield (fine, montmorillonitic, mesic Aridic Argiustoll) soils in 1983 and 1984. Nitrogen mineralized was also measured in fallow plots on Haynie and Wymore (fine, montmorillonitic, mesic Aquic Argiudoll) soils in 1984. The method only accurately predicted the amount of N mineralized in 104 d in fallow plots on Haynie soil. In all other cases, the method significantly overpredicted by 67 to 343% the amounts of N mineralized in the field. Among possible causes for the overpredictions may be an improper soil water content factor and the drying and sieving of the samples before incubation.
Involvement of Bacterial Siderophores in the Remedy of Lime‐induced Chlorosis in Peanut
Authors: Jurkevitch E. , Chen Y. , Hadar Y. 
Published: July 2010

AbstractA Pseudomonas putida strain isolated from peanut (Arachis hypogaea L.) roots excreted yellow‐green fluorescent siderophores (pigments) when grown under Fe‐deficient conditions. The pigments were purified in their Fe complex form. Chromatography yielded eight peaks, the first two representing >90% of the total. Physico‐chemical characteristics of the materials exhibiting these two peaks were similar to those of the pseudobactin‐pyoverdine class of siderophores. In two growth chamber experiments peanut plants grown on a highly calcareous soil were able to use the Fe from unpurified Fe‐siderophore produced by P. putida cultures. When supplied with 11 mg Fe kg−1 soil as Fe‐siderophore the chlorophyll concentration in the leaves was 75% of that of FeEDDHA (ethylenediamine di‐o‐hydroxyphenylacetic acid)‐treated plants. Control plants that were not fertilized with Fe contained only 35% chlorophyll of that of FeEDDHA‐treated plants. Nonferrated siderophores were ineffective in correcting Fe deficiency. Relative chlorophyll concentration in the leaves of the treatment supplemented with Fe‐siderophore and bacterial cells was similar to that of applications that did not contain bacterial cells. In a second experiment, 100% remedy of the deficiency was achieved when 19 mg Fe kg−1 soil as Fe‐siderophores was applied in comparison to 1.2 mg Fe kg−1 soil as FeEDDHA. The degree of remedy of chlorosis was independent on the frequency of application (two or four times a month). In these treatments total bacterial and fluorescent pseudomonad counts [colony‐forming units (cfu) g−1 dry roots] were significantly higher than in the unfertilized and FeEDDHA treatments. The level of DTPA (diethylenetriam‐inepentaacetic acid) extractable Fe at the end of the growth period in both experiments was significantly higher in Fe‐siderophore amended soils than in FeEDDHA‐treated soils. In a third experiment, the siderophore Ferrioxamine B (FOB) was used as a source of Fe. Iron applications of 22.5 and 45 mg Fe kg−1 soil as FOB were required to reach 70 and 97%, of the chlorophyll concentration of the FeEDDHA‐treated plants, respectively. It was concluded that bacterial siderophores may serve as a remedy to lime‐induced chlorosis in plants grown in calcareous soils.