bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alkaline Oxidation Method for Determination of Total Sulfur in Plant Materials1
Authors: Tabatabai M. A. , Chae Y. M. 
Published: July 2010

AbstractCurrent wet digestion methods available for determination of total S in plant materials are unsafe and usually give inaccurate results.A rapid and precise method of determining total S in plant materials has been developed. The plant sample is heated with NaOBr solution to oxidize plant S compounds to sulfate, and the sulfate thus formed is reduced to H2S by a modified Johnson‐Nishita procedure and determined colorimetrically as methylene blue. Its results for total Sare generally higher than those obtained by the HCIO4‐digestion method, suggesting possible loss of S, as gases, or incomplete oxidation of S during digestion of plant samples with HCIO4. In addition to being safe, digestion of plant samples with NaOBr is more rapid than with HCIO4. By using a bank of 10 distillation units, a single operator can perform 60 analyses in a normal working day.
Water Potential Evaluation of Three Germination Substrates Utilizing Polyethylene Glycol 20,0001
Authors: Berkat Omar , Briske D. D. 
Published: July 2010

AbstractNumerous problems exist in controlling substrate water potentials for germination investigations. Therefore, an evaluation of three germination substrates was conducted at four water potentials maintained by various concentrations of polyethylene glycol 20,000 (PEG). The substrates were: 1) PEG saturated paper (paper), 2) paper on PEG saturated vermiculite (vermiculite), and 3) paper on foam floating on PEG solution (foam). A water vapor seal was placed on half of the trays prior to placement in a controlled environment. Germination substrate water potentials were measured with a thermocouple psychrometer every 2 days for a 2‐week period. Germination substrate water potentials never fully equilibrated with the solution water potentials. Germination substrate water potential in the nonvapor sealed trays decreased 0.8 MPa within a 2‐day period while vapor sealed trays showed no appreciable decrease. At the end of the 12‐day period substrate water potentials had decreased 0.15 and 1.85 MPa for the vapor sealed and nonsealed trays, respectively. When both vapor‐sealed and non‐vapor sealed trays were considered, vermiculite and foam substrates exhibited a significantly higher water potential than paper. When only the vapor‐sealed trays were considered, the influence of type of germination substrate was reduced, although vermiculite exhibited a higher water potential than the foam. The foam substrate was considered most desirable because of ease of preparation and tendency to avoid accumulation of free‐standing solution.
Weed Control in Corn Planted into Untilled Winter Wheat Stubble1
Authors: Burnside Orvin C. , Wicks Gail A. 
Published: July 2010

AbstractAs reduced tillage production systems expand in the Great Plains, a critical need will be non‐tillage methods for controlling established weeds prior to planting the crop. This research dealt with finding selective weed control methods for corn (Zea mays L.) in an ecofarming system consisting of a winter wheat (Triticum aestivum L.)‐corn‐fallow rotation on a Sharpsburg silty clay loam (Typic Argiudolls) at Lincoln and a Holdrege silt loam (Typic Argiustolls) at North Platte, Nebraska. Both established and subsequently emerging weed species must be selectively controlled without tillage in order to better conserve the soil, water, energy, and labor requirements in this marginal corn production area. This research has as an objective the moving of dryland corn production further west in the Great Plains region. Adequate control of annual grass weeds as a group was more difficult than control of broadleaf weeds. The more difficult to control weed species were velvetleaf (Abutilon theophrasti Medic.), fall panicum (Panicum dichotomiflorum Michx.), large crabgrass [Digitaria sanguinalis (L.) Scop.], and clammy groundcherry (Physalis heterophylla Nees). Weed yields were the lowest and corn yields were the highest on plots receiving atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] at 2.2 kg/ha, cyanazine (2‐[[4‐chloro‐6‐(ethylamino)‐s‐triazin‐2‐yl]amino]‐2‐methyl‐propionitrile) at 2.8 kg/ha, or a combination of the two at 0.9 + 1.9 kg/ha. Four foliar‐active herbicide treatments—2,4‐D [(2,4‐dichlorophenoxy)acetic acid] at 1.1 kg/ha, 2,4‐D at 1.1 kg/ha + 9.4 liters/ha Sunspray 11E oil, paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) at 0.3 kg/ha, and glyphosate [N‐(phosphonomethyl)glycine] at 0.6 kg/ha—were equally effective for controlling established weeds and maintaining high corn yields when combined with the s‐triazine herbicides. The no‐till farmer has a number of herbicides available which will selectively destroy established and subsequently germinating weed species in corn without tillage.
Field Evaluation of Reference Crops in the Study of Nitrogen Fixation by Legumes Using Isotope Techniques1
Authors: Wagner George H. , Zapata Felipe 
Published: July 2010

AbstractNitrogen fixed by a legume crop can be measured in a field fertilized with labeled 15N when a suitable non‐fixing reference crop is grown also. Legume and reference crop, respectively, are used with 15N fertilizer to determine available soil plus fixed N and available soil N. Nitrogen derived from fixation is computed from the difference between these two estimates of N availability. Suitability of a reference crop depends on its utilization of fertilizer and soil N in the same proportion as the legume crop. Because this cannot be evaluated directly, the acceptability of reference crop data was examined by determining whether the proportion of fertilizer and soil S taken up by legume and non‐fixing reference crops is the same. Various reference crops for determining N fixation by broadbean (Vicia faba L.) and by soybean (Glycine max L. Merr.) were examined by this approach in field experiments on a Typic Eutrocrept using 15N and 35S labeled ammonium sulfate to determine plant available amounts (A‐values) of N and S in the soil.Nitrogen A‐values for broadbean were clearly higher than for any of the non‐fixing crops at two harvest dates. At physiological maturity of the legume, N fixation estimated from A‐value comparisons was approximately 140 kg/ha. Sulfur A‐values were reasonably similar among all crops studied but somewhat lower for oil radish (Raphanus sativus L.) which proved to be an inappropriate reference because it took up much more S than the other crops.Nitrogen A‐values for inoculated soybeans at the R3 stage of maturity were similar to those for the several reference crops including non‐nodulating soybeans. At stage R6, N fixation was clearly evident from A‐value comparisons but no greater than 60 kg/ha. By creating a N deficient condition in the soil using sucrose to immobilize N in an experiment with soybeans, the percentage of N in the crop derived from fixation was increased from 30 to 80%.
Evaluation of a Dual‐Radioisotope Instrument for Measuring Leaf Conductance and Photosynthesis1
Authors: Ramos C. , Hoffman G. J. , Hall A. E. 
Published: July 2010

AbstractModifications in both the design and operation of the dual‐radioisotope instrument are described. The accuracy and reliability of the modified instrument were then evaluated in both laboratory and field tests. Leaf conductance and net CO2 exchange rates determined with this instrument and by gas exchange methods in the laboratory were similar for both corn (Zea mays L.) and wheat (Tritictim aestivum L.). A field test of the instrument on barley (Hordeum vulgare L.) subjected to two levels of salinity gave coefficients of variation which indicated that errors attributable to the instrument and/or the plant material were less than 35% for leaf conductance and 16% for photosynthesis. The instrument provides rapid, simultaneous measurements of leaf conductance and photosynthesis under field conditions.
Forage Quality for Sheep and Chemical Composition Associated with Sulfur Fertilization on a Sulfur Deficient Site1
Authors: Jones M. B. , Rendig V. V. , Torell D. T. , Inouye T. S. 
Published: July 2010

AbstractImprovements in forage quality and yield have resulted from application of S fertilizer. The purpose of this study was to relate forage composition changes associated with S fertilization to quality, as measured by lamb growth, efficiency of feed eaten by lambs, in vitro digestibility, and blood serum sulfate levels. Five rates of S were applied on a Sutherlin soil series (Ultic Haploxerolls) in each of 2 successive years to two sets of plots, one set seeded to subclover (Trifolium subterraneum L.) (designated “clover‐grass”), the other to ryegrass (Lolium multiflorum L.). The ryegrass plots were also fertilized with N, and all plots received applications of P and K. The forage was harvested as hay, ground, pelleted, and fed to lambs in two feeding trials with an average duration of 60 days.Sulfur concentrations ranged from 0.13 to 0.24% in the clover‐grass and from 0.09 to 0.22% in ryegrass. Protein ranged from 10.3 to 13.1% in the clover‐grass, and from 6.3 to 8.0% in the ryegrass. The N/S ratios ranged from 8 to 13 for the clover‐grass and from 6 to 13 for ryegrass.Application of S to the soil increased the average daily gains (ADG) of lambs for the two trials, from 141 to 186 g for the clover‐grass, and from 32 to 84 g for the ryegrass. Ninety percent of the maximum ADG (defined as a critical value) was obtained at 0.19% S in the clover. A critical value is not given for ryegrass since ADG increased with each increment of S added, including the highest level of S applied. This was likely due to N being more limiting than S in the diet of the lambs. Blood serum sulfate‐S in the lambs was more closely related to % S in clover‐grass forage (r2 = 0.76) than to % S in ryegrass (r2 = 0.50). A good relationship (r2 = 0.90) was found between serum sulfate‐S level and sulfate‐S intake for both forages. Blood sulfate was related to growth rate of lambs by a negative exponential function, with estimated critical values of 30 and 39 µg/ml, respectively, for the ryegrass and the clover‐grass hay pellets.An average of 11 kg feed/kg gain was required for sheep on clover‐grass with zero S applied. This dropped to nine where S was applied. On ryegrass this ratio was 48 on the zero S treatment, but it dropped to an average of 18 with S applied.
Field Comparison of the Nitrogen‐15 and Difference Methods of Measuring Nitrogen Fixation1
Authors: Talbott Helen‐Jean , Kenworthy W. J. , Legg J. O. 
Published: July 2010

AbstractFurther investigation of the methods of evaluating N2 fixation under field conditions is essential, since the accuracy and reproducibility of the method of measurement have profound effects on the results of an experiment; and, opinions differ concerning which method provides the best estimates. The amount of N2 fixed and the percentage of total plant N from biologically fixed N in field‐grown soybeans [Glycine max (L.) Merr.] measured by the difference method were compared with corresponding estimates from a 15N‐tracer technique in which 15N‐labeled soil organic matter is used as the tracer material. In 1977 and 1978, six N2‐fixing soybean genotypes were grown in rows alternating with rows of a nonnodulating genotype (Clark rj1 rj1) in replicated field plots on a Mattapex silt loam (fine‐silty, mixed, mesic Aquic Hapludult) where the 15N was incorporated into the soil organic fraction. The difference method compared total N contents of the N2‐fixing and adjacent nonnodulating plants. The 15N method determined the dilution in the N2‐fixing plants of soil‐derived 15N by symbiotically‐fixed N. Plants were sampled at 49, 70, and 91 days after planting and at full maturity in 1977, and at 62 and 112 days after planting in 1978. Sources of variation for the estimates were identified as the total N accumulation in the nonnodulating genotype for the difference method, and the 15N concentration in the nonnodulating genotype for the 15N method. Estimates from the difference and 15N methods for the amount of total N fixed were highly correlated (r = 0.89 for 1977, r = 0.92 for 1978). The percentage of total N fixed varied between the two methods (r = 0.32 for 1977, r = 0.69 for 1978) which was attributed to spatial variation of available soil N. The 15N method provided more accurate estimates for the percentage of total N fixed because the 15N concentration was less variable than the total N accumulation in the nonnodulating genotype.
Backhoe‐Mounted Soil‐Coring Machine
Authors: White R. J. G. 
Published: July 2010

AbstractA hydraulic soil‐coring machine has been designed and constructed to attach to the arm of a tractor‐mounted backhoe. The system reduces the passes through a plot with sampling equipment and also allows samples to be taken with the tractor outside the plot when soil and/or crop conditions do not allow access. It has been successfully used in summer row crop experiments for: (i) taking small diameter (to 5 cm) intact soil cores to a maximum depth of 2 m, (ii) inserting access tubes for soil‐water monitoring using a neutron probe, and (iii) placing large diameter tubes (up to 30 cm) to shallow depths (45 cm) for nutrient isotope studies.
Grain Protein Percentage, Kernel Hardness, and Grain Yield of Winter Wheat with Foliar Applied Ureal1
Authors: Altman D. W. , McCuistion W. L. , Kronstad W. E. 
Published: July 2010

AbstractIn the Pacific Northwest a major constraint to growing hard red winter wheat (Triticum aestivum L.) is the consistently low grain protein percentage observed. Foliar fertilization of winter wheat offers a potential for increasing grain protein percentage when applied around flowering. The main objective of this study was to determine the effect of foliar urea sprays on grain protein percentage, grain yield, and kernel hardness of 10 genotypes of winter wheat when grown in the field under four diverse environments. Also, immature spikes were analyzed after foliar treatments for percent protein, and optimal grain uptake of foliar applied N was measured under controlled conditions using 15N labelled urea. Foliar sprays of urea increased grain protein percentage by 16 and 10 % and yield by 8 and 3% over the control of no applied urea in two environments. Combinations of topdressing and foliar sprays produced yields equivalent to standard topdressed plots at all locations and increased grain protein percentage by 12 and 9% in two of the four environments tested. Foliar applications did not alter kernel hardness overall. Significant genotype X N treatment interactions were found for grain protein percentage, grain yield, and kernel bardness. Spike protein analysis at flowering showed N treatment effects 2 weeks after foliar applications in the field, and the ranking of treatments corresponded closely with that determined by grain analysis at harvest. Uptake of N from foliar sprays was also confirmed with a mean of 44.1 % of applied 15N recovered in grain samples. Genotypes differed for I5N recovery rates in the grain from 48.3% for ‘Stephens,’ a low protein soft white cultivar, to 39.9% for ‘Centurk,’ a higher protein hard red cultivar. Daylength after treatment also affected recovery rates with 41.4 and 46.9% of applied 15N being recovered for 12 and 18 hours respectively.
Sulfur Nutrition of Rice. III. A Comparison of Fertilizer Sources for Flooded Rice
Authors: Samosir Solo , Blair Graeme J. 
Published: July 2010

AbstractSulfur deficiency in rice (Oryza sativa L.) is becoming a more significant constraint to rice yields as the use of high analysis, low S‐containing fertilizers increases. There is a wide range of sulfatic fertilizers available and these have not been tested, to any degree, under flooded conditions. A pot experiment was conducted on a low fertility Paleudult soil to test the S‐supplying capacity of ammonium sulfate, gypsum, elemental S, and sulfur coated urea (SCU) applied at 30 kg S/ha to flooded rice. At 25 days after transplating (dat), fertilizer source had no significant effect on total top yield and S uptake was lower in the control, elemental S and SCU treatments. By 50 dat S deficiencies were evident in the control and SCU treatments where tiller number, yield, and % S levels were decreased. Sulfur uptake from SCU was not significantly different from the zero S control over the 113 day growing period. At maturity yields and S uptake were not significantly different between the gypsum, elemental S (100% <60 mesh), and ammonium sulfate sources. These results confirm the suitability of fine (100% <60 mesh) elemental S as a S source for rice, and show that S from SCU is not available to flooded rice at least in the first crop after application.
Influence of Mycorrhizal Fungi on the Mineral Nutrition and Yield of Onion in Saline Soil1
Authors: Ojala J. C. , Jarrell W. M. , Menge J. A. , Johnson E. L. V. 
Published: July 2010

AbstractIn a number of studies, salt‐affected plants have been found to contain lower P concentrations than non‐salinized control plants. This study was performed to evaluate the ability of two vesicular‐arbuscular mycorrhizal fungi (VAM) to improve the yield and salt tolerance of onion (Allium cepa L. var. Burpee hybrid 5276) by facilitating P uptake from a saline soil. Onion was grown in a Delhi loamy sand soil (mixed, thermic Typic Xeropsamment) in the glasshouse under ambient light conditions. Plants infected with Glomus fasciculatus and G. monosporus VAM had higher bulb and total onion dry weights than nonmycorrhizal plants in P deficient soil at low (−0.06 MPa bars) irrigation water solute potential (Ψ3), intermediate (−0.20 MPa Ψ3), and high (−0.41 MPa). Plants infected with G. fasciculatus yielded significantly more than G. monosporus plants at low (Ψ3 = −0.06 MPa) and high (Ψ3 = −0.41 MPa) salinity; at Ψ3 = −0.20 MPa bars, yields were not significantly different for mycorrhizal plants. Mycorrhizal infection with both fungi tended to decrease linearly with increasing salinity, although it remained high (58 to 46%) even at high salinity. As salinity increased, nonmycorrhizal plants developed lower concentrations of P, Mg, and K in shoot tissues, K in bulb tissues, with lower total uptake (mg plant−1) of Ca, Mg, K, Zn, and Mn. Mycorrhizal onion had greater concentrations of P and K in shoot tissues, P in bulb tissues, and greater P, Ca, Mg, Na, K, Zn, and Fe total uptake than nonmycorrhizal plants at intermediate soil salinity. Tissues of mycorrhizal plants contained only 70 % as much Mn as nonmycorrhizal plants; high Zn and Fe concentrations were reduced in plant tissues at high salinity compared with intermediate and low salinity. Improved nutritional status of onion plants due to mycorrhizal fungi is at least partially responsible for increased plant growth under saline conditions, although other mechanisms may be involved.
Changes in Composition of Alfalfa, Red Clover, and Birdsfoot Trefoil during Autumn1
Authors: Collins Michael 
Published: July 2010

AbstractConsiderable research has been conducted to evaluate the influence of harvest management of alfalfa (Medicago sativa L.) during late summer and autumn on persistence and subsequent forage yields. These studies generally have not included data on changes in forage quality during autumn. The objective of this experiment was to measure changes in forage yield and composition of alfalfa, red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus corniculatus L.) in response to delay of harvest during autumn. Small plots of each species were seeded on Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudoll) using chemical weed control. Regrowth was measured following a late August harvest each season. Separate plots of each species were harvested on the average dates of 7, 17, and 28 October and 8 and 19 November during 1979 and 1980. Dry matter yield of alfalfa increased by 16% between 7 and 17 October in 1979 and by 22% in 1980. Yield of all three species declined after the mid‐October harvest in both years. Nitrogen concentration in forage of all species declined between 7 October and 8 November in 1979, and between 7 and 28 October in 1980. In vitro dry matter disappearance (IVDMD) did not change between 7 and 28 October but generally declined by 19 November. Total nonstructural carbohydrate concentration increased between 7 and 28 October and declined thereafter. Neutral detergent fiber concentration in alfalfa did not increase between 7 and 28 October in 1979 but increased after that date. Red clover did not increase in neutral detergent fiber concentration during autumn in 1979. In 1980 forage of all species increased in neutral detergent fiber after 8 November. The concentrations of P, K, and S in the forage of all three species declined during autumn. Red clover was lower in S concentration (0.21 %) than alfalfa (0.32 %) or birdsfoot trefoil (0.29 %). Calcium concentration increased significantly during autumn. The concentration of Mg in all three species remained unchanged or increased during autumn. These results indicate that significant yields of high quality forage were produced following harvest in late August. The three legumes differed in yield but were generally similar in IVDMD and N concentration on a particular harvest date. Forage yield declined more rapidly between 7 October and 17 November than did forage IVDMD or N concentration.
Band Application of Sulfuric Acid or Elemental Sulfur for Control of Fe‐Deficiency Chlorosis of Soybeans1
Authors: Frank S. J. , Fehr W. R. 
Published: July 2010

AbstractIron‐deficiency chlorosis can reduce the productivity of susceptible soybean [Glycine max (L.) Merr.] cultivars when grown on certain calcareous soils. Two experiments were conducted to evaluate the use of S and sulfuric acid (H2SO4) for the control of Fe‐deficiency chlorosis of soybeans grown on calcareous Harps (fine‐loamy, mesic, Typic Calciaquoll) soils in the field. In Exp. 1, H2SO4 was applied at eight rates from 0 to 123.5 g/m of row at two depths under the seed, 2.5 and 5 cm. Two cultivars susceptible to Fe‐deficiency chlorosis, ‘Corsoy’ and Pride ‘B216’, were evaluated with each rate in five Iowa environments during 1978 and 1979. In Exp. 2, H2SO4 was applied 5 cm below the seed at the same rates as in Exp. 1, and S was applied at the same depth as a powder at rates equivalent to the amount of S applied in the H2SO4. Corsoy and B216 were evaluated with both chemicals on calcareous soils in four Iowa environments during 1979. Response in both experiments was evaluated by visual chlorosis ratings before flowering, and also by plant height at maturity in Exp. 1. Sulfuric acid significantly reduced chlorosis and increased plant height for both cultivars and depths of placement at the rates of 30.9, 61.8, and 123.5 g/m when averaged across environments. Only at the 123.5 g/m rate did placement of the H2SO4 5 cm below the seed cause a significantly greater reduction in chlorosis score and increase in height than at the 2.5‐cm depth. None of the H2SO4 treatments completely prevented chlorosis in either cultivar. Application of S did not cause significant reduction in chlorosis scores at any of the rates used.