bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Application of Two Organomineral Fertilizers on Nutrient Leaching Losses and Wheat Crop
Authors: Tejada M. , Benitez C. , Gonzalez J. L.
Published: May 2005

The topic of how to decrease environmentally adverse effects of agriculture without losing too much crop yield is an important issue. In this respect, nutrient leaching losses were studied from a soil (land fallowing is not practiced) treated with two types of organomineral fertilizers [organomineral fertilizer (OMF) and organic + inorganic fertilizer mixture (O+IF), respectively]. Inorganic N losses were greatest in the soil treated with the O+IF, followed by those treated with the OMF, the former of which resulted in more gradual losses than the latter. Losses of other elements supplied by the fertilizers, particularly P and K, were greatest for the O+IF, followed by OMF treatment. The high nutrient losses observed in the soil treated with the O+IF make it advisable to use an OMF in soils with an abundant water supply. The highest N/P ratios were produced by the OMF, which suggest a lower eutrophication risk in drainage waters from soils treated with this fertilizer. Wheat (Triticum aestivum L. cv. Cajeme) yield parameters obtained and the alveographic assays showed that the OMF has a great potential of being used, at least on the wheat variety tested and under the pedoclimatic conditions prevailing in the study area. In this respect, application of OMF gave a significant increase in grain gross protein content of 2.9%, an increase in number of grains per spike of 2.2%, a significant increase in number of spikes per square meter of 3.4%, an increase in 1000‐grain weight of 3.9%, and a significant yield increase of 2.5% with respect to the O+IF treatment.
Cotton Canopy Reflectance at Landscape Scale as Affected by Nitrogen Fertilization
Authors: Bronson Kevin F. , Booker J. D. , Keeling J. Wayne , Boman Randy K. , Wheeler Terry A. , Lascano Robert J. , Nichols Robert L.
Published: May 2005

Multispectral reflectance of crop canopies has potential as an in‐season indicator of N status in cotton (Gossypium hirsutum L.). The objectives of this study were to correlate leaf N with reflectance at 16 wavebands from 450 to 1700 nm and to assess the effect of N fertilization on vegetative ratio indices using two bands of reflectance. We also compared regressions of leaf N on ratio indices with partial least squares (PLS) regression using reflectance at 16 wavebands. Reflectance was measured at 50 cm above the canopy at 135 points in a 14‐ha field of irrigated cotton at early squaring in the Texas High Plains in 2002 and at an 80‐cm height in 2003 and 2004. Leaf N had weak, negative correlation with green reflectance in all 3 yr. Normalized difference vegetative indices (NDVIs) using red (670 nm) or green (550 nm) reflectance were significantly greater in N‐fertilized plots than zero‐N plots in 2 of 3 yr. However, the NDVIs related poorly or not at all with leaf N, biomass, and lint yield. Leaf N was estimated by PLS regression with three factors having R
2 of 0.64 in 2002 and 2004 when an N fertilizer response was observed. In 2003, there was no added N effect, and the R
2 for PLS regression of leaf N was 0.41. The poor correlation between NDVIs and leaf N was not expected, and these results suggest that use of NDVIs to determine need of in‐season N may be most successful using well‐fertilized areas and the sufficiency index approach.
Corn Response, Nitrogen Uptake, and Water Use in Strip‐Tillage Compared with No‐Tillage and Chisel Plow
Authors: Licht Mark A. , Al‐Kaisi Mahdi
Published: May 2005

Tillage systems are among the many factors that affect soil productivity. The challenges associated with different tillage systems have prompted the need to compare corn (Zea mays L.) production under strip‐tillage (ST), chisel plow (CP), and no‐tillage (NT) systems. The study was conducted on two Iowa State University Research and Demonstration Farms in 2001 and 2002. One site was at the Agronomy Research and Demonstration Farm near Ames, IA, where the soils were Nicollet loam (Aquic Hapludolls) and Webster silty clay loam (Typic Haplaquolls). The second site was at the Northeast Research and Demonstration Farm near Nashua, IA, where the soils were Kenyon loam (Typic Hapludolls) and Floyd loam (Aquic Hapludolls). Corn final emergence rate index was slightly higher in ST than either NT or CP. Grain yield, dry matter production, and N uptake were generally similar in the three tillage systems. Soil moisture storage in the 0‐ to 30‐ and 0‐ to 120‐cm soil depths and grain water use efficiency show no significant differences between tillage systems. It was apparent that after 2 yr of ST, there were limited advantages for ST when compared with either NT or CP.
Economic Analysis of Replacing Endophyte‐Infected with Endophyte‐Free Tall Fescue Pastures
Authors: Zhuang Jun , Marchant Mary A. , Schardl Christopher L. , Butler Courtney Murrell
Published: May 2005

Cattle (Bos taurus) consuming tall fescue pastures infected with the endophyte Neotyphodium coenophialum often suffer physiological disorders that reduce animal performance. One solution is to replace endophyte‐infected tall fescue pastures with an endophyte‐free mixture. A benefit‐cost analysis was conducted to determine the profitability of pasture restoration. The profitability of this action depends on the percentage of endophyte in existing pastures, the discount rate, stand life of the endophyte‐free tall fescue variety, pasture stocking rates, product price, baseline calving rates, and the initial investment of replacement. In our benefit‐cost analysis, assuming the stand life of endophyte‐free tall fescue is 12 yr and the stocking rate is 1.20 head ha−1, we determined a critical infestation level of 74%. Thus, under these conditions pasture replacement should be profitable if, in the existing pastures, >74% of the fescue plants are infected with toxic endophyte. In sensitivity analyses, realistic variations in the discount rate, pasture stand life, stocking rate, product price, baseline calving rate, and initial investment of replacement generated new net present values and critical infestation levels. The most influential variable was the stocking rate. The critical infestation level decreased dramatically to 25% at a stocking rate of 4.0 head ha−1 and increased dramatically to 93% at a stocking rate of 0.82 head ha−1. Since infestation levels are often >70%, these results imply that for many livestock producers pasture replacement might be profitable compared with retaining endophyte‐infected fescue stands.
Effect of Low Water Temperature on Rice Yield in California
Authors: Roel A. , Mutters R. G. , Eckert J. W. , Plant R. E.
Published: May 2005

Water temperature has increasingly become a matter of concern for California rice (Oryza sativa L.) growers due to a need for public water agencies to improve habitat for fish. Prudent management of water resources to balance the needs of environmental and agricultural interests requires the quantification of water temperature effects on rice productivity. Our objective was to evaluate two alternative thermal unit models for the effect of low water temperature on yield. One model was based on the total number of hours below a given threshold water temperature Tb (abbreviated TNHB Tb) and the other was based on the concept of inverse degree days (i.e., degree days below a given threshold water temperature) (abbreviated IDD). We tested these models at a range of values of Tb between 10 and 25°C on data from two commercial fields during 2 yr. Results showed that the effect of low water temperature may be much greater than would be apparent from the visual appearance of the rice plants. Values of IDD and TNHB Tb were very highly correlated for 4 of the 4‐yr field combinations. A logistic curve model based on TNHB 20°C provided the best fit to the aggregated data.
Illinois Bundleflower Forage Potential in the Upper Midwestern USA: I. Yield, Regrowth, and Persistence
Authors: Fischbach Jason A. , Peterson Paul R. , Sheaffer Craig C. , Ehlke Nancy J. , Byun Jaehyun , Wyse Donald L.
Published: May 2005

Illinois bundleflower [Desmanthus illinoensis (Michx.) MacMillan] is a warm‐season perennial legume native to the central plains of the USA with potential as both a forage and grain crop. The effects of management variables on Illinois bundleflower (IBF) forage production in the upper midwestern USA have not been evaluated. We evaluated the effects of maturity at harvest, cutting height, and N fertilization on forage yield, regrowth, and persistence of three northern ecotypes of IBF. Field experiments were established at four Minnesota locations in 2000. Total‐season forage yields in postestablishment years ranged from 2.5 to 5.3 Mg dry matter (DM) ha−1 across environments. First‐harvest forage yield increased (P < 0.05) from 2.8 Mg DM ha−1 at early flower in mid‐July to 4.2 Mg DM ha−1 at late pod in mid‐August. In mid‐September, within‐season regrowth averaged 1.7 Mg ha−1 from plants previously cut at early flower and 0.6 Mg ha−1 from plants cut at late pod. A 35‐cm cutting height resulted in 60% more regrowth yield (P < 0.05) than a 15‐cm cutting height, but only in plants harvested at early flower. Plants cut at late pod in 2001 did not persist into 2002. October root total nonstructural carbohydrate (TNC) concentration ranged (P < 0.05) from 244 g kg−1 in plants cut at late pod to 280 g kg−1 in plants left uncut. Complete winterkill of all treatments at all locations between 2002 and 2003, regardless of October TNC level, may have been caused by below‐average snow cover. Illinois bundleflower can provide summer forage in the upper midwestern USA, but persistence in monoculture is limited, especially in harsh winters.
Long‐Term Effects of Recycled Wastewater Irrigation on Soil Chemical Properties on Golf Course Fairways
Authors: Qian Y. L. , Mecham B.
Published: May 2005

The increasing water shortage in the arid and semiarid western USA requires use of recycled wastewater (RWW) when possible. Recycled wastewater has become a common water source for irrigating golf courses and urban landscapes, creating the need to study the effects of RWW irrigation on soil chemical properties. We compiled soil test data from fairways of 10 golf courses that were near metropolitan Denver and Fort Collins, CO. Among these courses, five had been irrigated exclusively with domestic RWW [electrical conductivity (EC) = 0.84 dS m−1] for 4, 13, 14, 19, and 33 yr, respectively. The other five with similar turf species, age ranges, and soil textures had used surface water (EC = 0.23 dS m−1) for irrigation. Our results indicated that soils (sampled to 11.4 cm) from fairways with RWW irrigation exhibited 0.3 units of higher pH and 200, 40, and 30% higher concentrations of extractable Na, B, and P, respectively. Compared with sites irrigated with surface water, sites irrigated with RWW exhibited 187% higher EC and 481% higher sodium adsorption ratio (SAR). Comparison of soil chemical properties before and 4 or 5 yr after RWW irrigation on two golf courses also revealed the following findings: (i) 89 to 95% increase in Na content; (ii) 28 to 50% increase in B content; and (iii) 89 to 117% increase in P content at the surface depth. Regular monitoring of site‐specific water and soil and appropriate management are needed to mitigate the negative impacts of sodium and salts accumulations.
Predicting Rice Yield Using Canopy Reflectance Measured at Booting Stage
Authors: Chang Kuo‐Wei , Shen Yuan , Lo Jeng‐Chung
Published: May 2005

Abilities to estimate rice (Oryza sativa L.) yields within fields from remote sensing images is not only fundamental to applications of precision agriculture, but can also be very useful to food provisions management. Major objectives of this study were to identify spectral characteristics associated with rice yield and to establish their quantitative relationships. Field experiments were conducted at Shi‐Ko experimental farm of TARI's Chiayi Station during 1999–2001. Rice cultivar Tainung 67, the major cultivar grown in Taiwan, was used in the study. Various levels of rice yield were obtained via N application treatments. Canopy reflectance spectra were measured during entire growth period, and dynamic changes of characteristic spectrum were analyzed. Relationships among rice yields and characteristic spectrum were studied to establish yield estimation models suitable for remote sensing purposes. Spectrum analysis indicated that the changes of canopy reflectance spectrum were least during booting stages. Therefore, the canopy reflectance spectra during this period were selected for model development. Two multiple regression models, constituting of band ratios (NIR/RED and NIR/GRN), were then constructed to estimate rice yields for first and second crops separately. Results of the validation experiments indicated that the derived regression equations successfully predicted rice yield using canopy reflectance measured at booting stage unless other severe stresses occurred afterward.
Development of a Leaf‐Level Canopy Assimilation Model for CERES‐Maize
Authors: Lizaso J. I. , Batchelor W. D. , Boote K. J. , Westgate M. E.
Published: May 2005

Calculating crop growth rate as the product of intercepted light and radiation use efficiency may yield inaccurate predictions under stress conditions. A more mechanistic simulation of photosynthesis and respiration may be required to improve model accuracy under stresses. We developed a leaf‐level photosynthesis and respiration model for maize (Zea mays L.) and linked it to CERES‐Maize. The new model has three components that simulate light absorption, instantaneous leaf gross assimilation, and canopy respiration. Daily solar radiation was fractioned into hourly direct and diffuse components, and transformed into hourly photosynthetically active radiation (PAR). Extinction coefficients for direct and diffuse PAR were calculated, and a hedgerow approach followed to restrict the calculation of leaf area index (LAI), light interception, and photosynthesis to the fraction of ground shaded by the canopy. Light absorption was calculated for sunlit and shaded fractions of LAI. Instantaneous gross assimilation per leaf considered the effects of light intensity, leaf age, and air temperature, and was integrated for daylight hours and green leaf area. Maintenance and growth components of respiration are computed separately. The new model was linked to CERES‐Maize and provided reasonable estimates of instantaneous leaf gross assimilation as well as daily trends of canopy gross assimilation and respiration. It also conforms to the standards of CERES‐Maize, thus requiring only a minimum set of daily weather inputs (solar radiation, maximum and minimum temperature, and rainfall). The model supports the simulation of leaf‐level processes such as hail damage, mechanical damage, herbivory, leaf pathologies, detasseling, and others.
Applying Thermal Time Scales to Sunflower Development
Authors: Aiken R. M.
Published: May 2005

Knowledge of sunflower (Helianthus annuus L.) development can support integrated pest management and cultural practices to achieve crop yield potential while reducing production costs. The objective of this research was to establish continuous, quantitative relationships among thermal time (two computation methods), photoperiod, and the progression of vegetative leaf appearance and reproductive development in sunflower. Empirical models were fit to phenostage observations for an oilseed hybrid during five planting periods; two analogous sets of coefficients corresponded to calculations of thermal time that assumed linear or optimized developmental responses to temperature. The resulting relationships were tested for predictive value by using similar observations for another oilseed and for a confection hybrid. Predictive accuracy ranged from 67 to 91% for leaf appearance and from 90 to 95% for reproductive phenostage. Field observations confirm earlier reports of long‐day photoperiod response for thermal time requirements to bud‐visible phenostage. Evidence for short‐day response for thermal time to maturity was also detected. The relationships are consistent with recent published reports of sunflower development and are suitable for forecasting sunflower phenostages, given knowledge of thermal time requirements to R1 and R9 phenostages and photoperiod sensitivity.
Improved Water Use Efficiency Associated with Cultivars and Agronomic Management in the North China Plain
Authors: Zhang Xiying , Chen Suying , Liu Mengyu , Pei Dong , Sun Hongyong
Published: May 2005

Both winter wheat (Triticum aestivum L.) and maize (Zea mays L.) are the two staple crops of the North China Plain (NCP) that are combined in a single‐year rotation. While annual evapotranspiration increased slightly, field studies conducted at Luancheng Station indicated that crop yield improved by 50% and resulted in significant water use efficiency (WUE) increases from 1982 to 2002. Water use efficiency has improved from 10 to 15 kg mm−1 ha−1 for winter wheat and from 14 to 20 kg mm−1 ha−1 for maize in the Piedmont of Mt. Taihang in the NCP. Yield increase was associated with the increase in kernel numbers per unit area without alteration of the weight of the kernels for both winter wheat and maize. Number of kernels per spike of winter wheat was increased from about 22 for cultivars used in 1980s to about 28 for cultivars used presently. Number of kernels per ear of maize was increased from about 300 for cultivars used in 1980s to about 450 presently. From the early 1990s, combine had been used to harvest winter wheat, allowing straw mulch to be applied to maize. Measurements of WUE from 1987 to 1992 and again from 1997 to 2002 showed that WUE of maize under mulch was significantly higher than that without mulch. Mulching reduced soil evaporation loss by 40 to 50 mm per annum measured by microlysimeters, and WUE was averagely improved 8 to 10% for the 12 seasons. An improvement in irrigation scheduling had also improved WUE. Irrigation applications to winter wheat were reduced from about eight times in 1980s to about four times presently. Field tests from 1999 to 2004 still showed that reducing the present number of seasonal wheat irrigations to either three, two, or one depending on seasonal rainfall would benefit both grain production and WUE of winter wheat.
Surface Application of Lime for Crop Grain Production Under a No‐Till System
Authors: Caires Eduardo F. , Alleoni Luís R. F. , Cambri Michel A. , Barth Gabriel
Published: May 2005

The effectiveness of surface application of lime to soils under a no‐till (NT) system, particularly with regard to subsoil acidity, is uncertain, and long‐term data is needed to determine optimum surface liming rates in this cropping system. A field experiment was performed in the period from 1993 through 2003 in Paraná State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox to evaluate the extent of the downward movement of surface‐applied lime in a NT system, and the effect on grain yields under crop rotation. The treatments consisted of dolomitic limestone at the rates of 0, 2, 4, and 6 t ha−1, calculated to raise the base saturation in the topsoil (0–20 cm) to 50, 70, and 90%. Surface‐applied lime under NT was effective in alleviating soil acidity below the point of placement, and increased the cumulative grain yield of the crops. The effects of surface liming on all three acidity‐related variables (pH, Al, and basic cations) were significant at 0‐ to 5‐ and 5‐ to 10‐cm depths from 1 yr onward, and also at the 10‐ to 20‐cm depth from 2.5 yr onward, remaining consistent for a period of up to 10 yr after liming. The maximum economic yield was obtained at 4 t ha−1 of limestone, showing that the lime rate estimated by the soil base saturation method at 70% in the 0‐ to 20‐cm depth was appropriate for surface liming recommendation in a NT system.
Emergence and Survival of Pasture Species Sown in Monocultures or Mixtures
Authors: Skinner R. Howard
Published: May 2005

Plant–plant interactions during seedling establishment can markedly affect the composition of pasture communities. This research examined the emergence, mortality, and early growth of four forage species commonly found in temperate northeastern U.S. pastures. Species were selected based on functional group (grass vs. legume) and relative drought tolerance. Drought‐tolerant species included ‘Penlate’ orchardgrass (Dactylis glomerata L.) and ‘Viking’ birdsfoot trefoil (Lotus corniculatus L.), while drought‐sensitive species included ‘Basion’ perennial ryegrass (Lolium perenne L.) and ‘Will’ white clover (Trifolium repens L.). Seeds were sown as monocultures, as grass–legume binary mixtures, and as a complex, four‐species mixture. Mixture complexity had only minor effects on seedling emergence. However, legume mortality was significantly reduced in the complex compared with other mixtures in a year when high temperature and drought stress limited seedling establishment. In most cases there was a negative effect of neighbors on survival as evidenced by reduced clustering of surviving compared with emerged seedlings and by a negative relationship between mortality rate and distance to the nearest neighbor. However, in a drought year, perennial ryegrass mortality decreased as distance to the nearest neighbor decreased, suggesting that survival was facilitated by the presence of neighbors. Although mixture complexity had significant effects on seedling emergence and mortality, species composition in the binary and complex mixtures could be predicted based on emergence and survival of monocultures. It appears that seedling emergence information gleaned from monocultures can be a useful tool for predicting initial species composition of more complex mixtures.
Yield‐Based Management Zones and Grid Sampling Strategies: Describing Soil Test and Nutrient Variability
Authors: Flowers Michael , Weisz Randall , White Jeffrey G.
Published: May 2005

Alternatives such as yield‐based management zones may solve problems associated with grid soil sampling while effectively describing soil test and nutrient variability. The main objective was to delineate yield‐based management zones using multiyear yield data and compare them with whole‐field average and grid soil‐sampling methods to determine the most effective strategy for describing soil test and nutrient variability. Research was conducted in four continuous no‐till fields that had varied cropping histories and yield monitor data for at least 3 yr from 1996 through 2000. Four yield‐based management zone methods, (i) mean normalized yield map (MNY), (ii) coefficient of variation map (CVM), (iii) MNY × CVM, and (iv) yield region map (YRM), were evaluated. Three grid soil‐sampling strategies, (i) grid cell, (ii) grid center, and (iii) grid center with kriging at two sampling distances (68 and 98 m), were also tested. Grid cell sampling consistently captured more soil test and nutrient variability than the grid center and grid center with kriging methods. Of the yield‐based management zone strategies, YRM was the most effective and in all four fields explained more soil test and nutrient variability compared with the whole‐field average approach. Yield region map also performed better than or similar to the 98‐m grid center and 98‐m grid center with kriging strategies. When the field had low soil test values, YRM was also nearly as effective in capturing nutrient recommendation variability as the 98‐m grid cell method. However, compared with all other strategies, the 68‐m grid cell method was the most effective way to describe soil test and nutrient variability.
Efficiency of Sulfuric Acid, Mined Gypsum, and Two Gypsum By‐Products in Soil Crusting Prevention and Sodic Soil Reclamation
Authors: Amezketa E. , Aragüés R. , Gazol R.
Published: May 2005

Sulfuric acid and gypsum‐like by‐products are potentially effective amendments in preventing soil crusting and reclaiming calcareous sodic soils. However, their relative efficiencies at chemically equivalent rates are not well documented. We evaluated the efficiency of four amendments (sulfuric acid, mined‐gypsum, and the by‐products coal‐gypsum and lacto‐gypsum) in crusting prevention of two calcareous nonsodic and sodic soils and in sodic soil reclamation. Treatments for crust prevention consisted of surface‐applied amendments at equivalent rates of 5 Mg pure‐gypsum ha−1. Treatments for sodic soil reclamation consisted of surface‐applied acid and soil‐incorporated gypsums at rates of 1 pure‐gypsum requirement. The efficiency of these amendments was evaluated by comparing the final infiltration rates (FIR) of the amended vs. the nonamended soils measured in disturbed‐soil columns pounded with low‐salinity irrigation water. Electrical conductivity (EC) and Na in the leachates of the sodic soil were measured. In the crusting prevention experiment, FIRs (mm h−1) of the nonsodic soil were 21 (nonamended), 33 to 35 (gypsum materials), and 53 (sulfuric acid), whereas those for the sodic soil were 0 (nonamended), 9 (lacto‐gypsum), 15 to 17 (coal‐ and mined‐gypsum), and 21 (sulfuric acid). In the sodic‐soil reclamation experiment, FIRs were 0 (nonamended), 8 to 9 (gypsum‐materials), and 17 (sulfuric acid) mm h−1. All amendments were effective in crusting prevention and soil reclamation, but sulfuric acid was the most efficient due to the fastest EC and Na reductions in the leachates. The three gypsum‐materials were equally effective in the reclamation process and in the nonsodic soil crusting‐prevention, whereas lacto‐gypsum was less efficient in the sodic‐soil crusting‐prevention.
Early‐Season Defoliation Effects on TopCross High‐Oil Corn Production
Authors: Mangen T. F. , Thomison P. R. , Strachan S. D.
Published: May 2005

High‐oil corn (Zea mays L.) produced with the TopCross grain production system is planted as a physical mixture (a TC Blend) containing 91% high‐yielding, male‐sterile hybrid (grain parent) seed and 9% pollinator seed. Field experiments were conducted at two locations in Ohio in 1999 and 2000 to determine if high‐oil corn (HOC) TC Blends are more sensitive to defoliation damage than their normal‐oil corn (NOC) hybrid counterparts consisting of 100% male‐fertile plants. Corn plants were 100% defoliated at V5 and 50 and 100% defoliated at V13. Defoliation similarly affected grain yield and oil concentration of HOC TC Blends and NOC hybrids. Complete defoliation at V13, averaged across years and hybrids, was the most damaging defoliation treatment, reducing grain yields 29%. Defoliation did not significantly alter grain oil concentration of HOC grain parents (74.5 g kg−1) or NOC (34.5 g kg−1). Defoliation caused similar responses in ear weights and oil concentrations in both components (the pollinator and the grain parent) of the HOC TC Blends. The lack of hybrid × defoliation interactions for ear yield components and various agronomic traits indicates that HOC TC Blends and their respective NOC counterparts responded similarly to early‐season defoliation over a range of environmental conditions. Guidelines for assessing early‐season leaf injury in conventional corn may be suitable for assessing leaf injury in HOC TC Blends.
Extractable Soil Phosphorus and Inorganic Nitrogen following Application of Raw and Anaerobically Digested Swine Manure
Authors: Loria Esteban R. , Sawyer John E.
Published: May 2005

Processing of swine (Sus scrofa domestica) manure in an anaerobic digester for biogas production is not a complete waste treatment process. Therefore, digested manure must be utilized in some manner, most likely as a source of plant nutrients. The objective of this study was to compare the effect of raw and digested liquid swine manure application on soil test P (STP) and inorganic N. A laboratory incubation study was conducted for 112 d, with a factorial combination of raw manure, digested manure, and inorganic fertilizer at five nutrient rates (0, 12.5, 25, 37.5, and 50 mg total P kg−1 and 0, 50, 100, 150, and 200 mg total N kg−1). Raw and digested swine manure produced the same NH4–N disappearance, NO3–N formation, net inorganic N, and increase in STP. Routine STP methods estimated similar P recovery with both manure sources, averaging 21% at the end of incubation. For the first 28 d of incubation, the STP levels were higher for fertilizer than manure; STP levels were similar for all P sources after 28 d. Nitrification of manure NH4 was rapid, reaching background concentrations by 14 d, with conversion rate similar to fertilizer NH4–N. By the end of incubation, maximum net extractable inorganic N, predominantly NO3–N, averaged 20% less than total applied N for both raw and digested manure. Anaerobic digestion did not substantially affect manure nutrient supply, and we conclude that anaerobically digested liquid swine manure can provide similar plant‐available N and P as expected from raw swine manure.
Coexistence of Native and Introduced Perennial Grasses following Simultaneous Seeding
Authors: Waldron Blair L. , Monaco Thomas A. , Jensen Kevin B. , Harrison R. Deane , Palazzo Antonio J. , Kulbeth James D.
Published: May 2005

Revegetation of disturbed semiarid lands requires rapid stabilization of ecological process and soil resources. Introduced species have been widely adopted because the slow establishment of native species frequently results in poor ecosystem recovery and further site degradation. Little research has documented the managerial possibilities and species interactions associated with simultaneously establishing native and introduced grasses on semiarid lands. We conducted a 3‐yr experiment at Fort Carson, CO, to evaluate if seven native perennial grasses would coexist with either Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], crested wheatgrass (Agropyron sp.), or Siberian wheatgrass [A. fragile (Roth) Candargy] after simultaneous seeding. Five grass mixes, each comprised of the seven natives and one introduced grass, and a standard military seed mix (mostly native grasses with a small introduced species component) were evaluated by comparing percentage ground cover of individual species. Predominance of crested and Siberian wheatgrass cover resulted in significantly lower native grass and weed abundance. In contrast, Russian wildrye and military treatments had lower introduced grass cover and high weed abundance, but much higher native grass cover. However, weed cover decreased to <5% in all treatments during the experiment. Western wheatgrass [Pascopyrum smithii (Rydb.) A. Löve] was responsible for >80% of the native species cover in the military treatment for all 3 yr, whereas the Russian wildrye treatments had a more balanced mix of several native species. These results provide insights into managerial considerations for revegetation and weed control for frequently disturbed rangelands and suggest that some introduced grasses may coexist with native grasses.
Effect of Row Spacing and Soybean Genotype on Mainstem and Branch Yield
Authors: Norsworthy Jason K. , Shipe Emerson R.
Published: May 2005

Partitioning of soybean [Glycine max (L.) Merr.] seed yield between mainstem and branch fractions across row widths and genotypes at recommended seeding rates is not well understood. A field experiment was conducted to evaluate the distribution of seed yield between mainstem and branch fractions of eight soybean genotypes grown in narrow (19 cm) and wide (97 cm) rows at recommended seeding rates. In contrast to adequate rainfall throughout the crop season in 2002, a lack of rainfall during reproductive development in 2003 caused differences in mainstem and branch yield components between years. Mainstem seed yields, averaged over years and genotypes, accounted for 45 and 69% of the total yield in wide and narrow rows, respectively. Mainstem seed yields, averaged over years and row widths, ranged from 62 to 142 g m−2 among genotypes. Ranking of mainstem and branch yields among genotypes was stable over environments. Similarly, row width did not influence mainstem yields among genotypes, but genotype branch yields in wide rows were different from those in narrow rows. Branch seed yields in narrow rows, averaged over years, ranged from 14 to 57% of total seed yield while 47 to 74% of total seed yield was produced on branches in wide rows. This research demonstrates considerable differences exist in mainstem and branch yields among genotypes and that genotypes having superior branch yield should be selected for wide rows while mainstem yield should be used as a selection criteria for narrow rows.
Spatial and Temporal Variation of Soil Nitrogen Parameters Related to Soil Texture and Corn Yield
Authors: Shahandeh H. , Wright A. L. , Hons F. M. , Lascano R. J.
Published: May 2005

The spatial variability of soil properties that affect the soil N budget and corn (Zea maysL.) grain yield were studied for 2 yr in south‐central Texas to better assess the potential for variable‐rate N fertilization. Residual soil NO3–N with depth and soil N mineralization (Nmin) potential and their relationships with soil total N, soil organic C, and clay content were characterized. Residual soil NO3–N to 60‐cm depth was more related to corn yield than NO3–N at shallower depths. Residual soil NO3–N showed temporal variation with spatial structure existing for NO3–N in the first year when NO3–N concentrations were high, but this variation was absent in the second year when NO3–N concentrations were low. The opposite trend was observed for soil Nmin. Soil total N exhibited temporal persistence. Soil Nmin showed significant correlations with soil clay content in both years. Temporal persistence of soil texture and variation in spatial structure for N parameters would likely result in different strategies for soil N management zones in 2002 vs. 2003. This experiment demonstrated the potential importance of soil texture for modifying fertilizer N recommendations. Texture generally is more easily determined than soil N parameters at the scale and intensity necessary for site‐specific N management.
Enhanced fluidization of nanoparticles in an oscillating magnetic field
Authors: Yu Qun , Dave Rajesh N. , Zhu Chao , Quevedo Jose A. , Pfeffer Robert
Published: May 2005

Some experimental observations on the fluidization characteristics of nanoparticles in the form of agglomerates with magnetic assistance are presented. The nanoagglomerates consist of Degussa Aerosil® R974 fumed silica, with a primary particle size of 12 nm. An oscillating AC magnetic field is used to excite large (mm size) permanent magnetic particles mixed in with the nanoparticle agglomerates, and the fluidization behavior of the nanoagglomerates, including the fluidization regime, the minimum fluidization velocity, the bed pressure drop, and the bed expansion are investigated. It is shown that, with the aid of an oscillating magnetic field at low frequencies, the bed of nanoparticle agglomerates can be smoothly fluidized, and the minimum fluidization velocity is significantly reduced. In addition, channeling or slugging of the bed disappears and the bed expands uniformly without bubbles, and with negligible elutriation. The bed expansion and the minimum fluidization velocity depend on the mass ratio of magnetic particles to nanoparticles, and the intensity and frequency of the oscillating magnetic field. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Epigenetik – ein Epizentrum der Genregulation: Histone und histonmodifizierende Enzyme
Authors: Biel Markus , Wascholowski Veit , Giannis Athanassios
Published: May 2005

Die Bekämpfung von Tumorerkrankungen durch die Entwicklung neuer Therapien ist eine der größten Herausforderungen unserer Zeit. Die Entschlüsselung des menschlichen Genoms hat zu Erkenntnissen hinsichtlich der molekularen Grundlagen körperlicher Fehlfunktionen geführt, sodass in vielen Fällen ein Zusammenhang zwischen fehlerhaften Genen und den resultierenden Krankheitsbildern hergestellt werden konnte. Die Modulation epigenetischer Mechanismen ermöglicht es, den Phänotyp einer Zelle zu beeinflussen, ohne ihren Genotyp zu ändern. So wichtig oder schädlich der Informationsgehalt eines einzelnen Genes auch ist – zur Entfaltung seiner Wirkung muss es aktiv abgelesen werden. Hierbei sind epigenetische Mechanismen maßgeblich eingebunden, und die Transkriptionsrate eines Gens ist direkt vom Modifikationsmuster der umgebenden Histonproteine sowie vom Methylierungsmuster der DNA abhängig. Diese Vorgänge beruhen auf Enzymen und sollten daher durch spezifische Modulatoren gezielt beeinflussbar sein. Sicherlich stehen alle Informationen schon in Form eines Vier‐Buchstaben‐Codes auf der DNA geschrieben – die Epigenetik beschreibt die Kunst, zwischen den Zeilen zu lesen.
Epigenetics—An Epicenter of Gene Regulation: Histones and Histone‐Modifying Enzymes
Authors: Biel Markus , Wascholowski Veit , Giannis Athanassios
Published: May 2005

The treatment of cancer through the development of new therapies is one of the most important challenges of our time. The decoding of the human genome has yielded important insights into the molecular basis of physical disorders, and in most cases a connection between failures in specific genes and the resulting clinical symptoms can be made. The modulation of epigenetic mechanisms enables, by definition, the alteration of cellular phenotype without altering the genotype. The information content of a single gene can be crucial or harmful, but the prerequisite for a cellular effect is active gene transcription. To this end, epigenetic mechanisms play a very important role, and the transcription of a given gene is directly influenced by the modification pattern of the surrounding histone proteins as well as the methylation pattern of the DNA. These processes are effected by different enzymes which can be directly influenced through the development of specific modulators. Of course, all genetic information is written as a four‐character code in DNA. However, epigenetics describes the art of reading between the lines.
Pharmacokinetics and tissue distribution of d‐alpha‐tocopheryl succinate formulations following intravenous administration in the rat
Authors: Teng Xiao Wei , Davies Neal M. , Fukuda Chie , Good Renee L. , Fariss Marc W.
Published: May 2005

Unlike d‐alpha tocopherol (T), d‐alpha tocopheryl succinate (TS) has the unique ability to selectively kill tumor cells while protecting normal tissue from toxic oxidative stress. The pharmacokinetics of TS and the serum and tissue disposition of TS were studied in male Sprague‐Dawley rats to delineate formulation dependent disposition between TS administered as the Tris salt (TS‐T) (a liposomal formulation) or as the free acid (TS‐FA) dissolved in polyethylene glycol (PEG) 400. The pharmacokinetics of TS was studied after single intravenous (i.v.) equimolar doses of 124 mg/kg TS‐T and 100 mg/kg of TS‐FA. Serial blood samples were collected via a catheter inserted into the right jugular vein and serum samples were analysed for TS and T levels using a reverse phase HPLC method. Terminal tissue samples were also collected at 24 and 48 h. After an acute i.v. dose of TS‐T, serum AUC, t1/2, Cl and Vd of TS were 2601.0±351.7 µg h/ml, 9.98±1.02 h, 0.049±0. 0073 l/h/kg and 0.7±0.14 l/kg (mean±SD), respectively. The acute i.v. administration of TS‐FA (PEG formulation) yielded results similar to those observed for TS‐T, with a serum AUC, t1/2, Cl and Vd of 2553.3±166.4 µg h/ml, 9.83±0.86 h, 0.039±0.0027 l/h/kg and 0.56±0.09 l/kg (mean±SD), respectively. Distribution into tissues and a low Cl was apparent, with the highest concentrations of TS in the liver and lung, regardless of formulation. As expected, baseline endogenous concentrations of T were present in both groups, with a net increase in T levels, occurring as TS was hydrolysed to T, which slowly peaked in serum between 7–8 h post‐dose. Intravenous TS administration, regardless of formulation, also resulted in significant T accumulation in all tissues examined, which was especially abundant in the liver and lung. Likewise, there was a lack of significant effect of formulation on the pharmacokinetics and tissue distribution of TS. The only significant formulation difference was a small but significant increase in serum T and liver T levels in the TS in PEG formulation group. These results indicate that TS may be especially useful for the targeted delivery of T and TS to the lung and liver for anti‐oxidant and anti‐cancer activity. Copyright © 2005 John Wiley & Sons, Ltd.
Stent‐based delivery of ABT‐578 via a phosphorylcholine surface coating reduces neointimal formation in the porcine coronary model
Authors: Collingwood Robin , Gibson Lori , Sedlik Souad , Virmani Renu , Carter Andrew J.
Published: May 2005

Stent‐based delivery of the antiproliferative and immunosuppressive macrocyclic lactone sirolimus reduces neointimal formation and restenosis by cytostatic inhibition of vascular smooth muscle cell proliferation. The objective of this study was to determine the feasibility and efficacy of stent‐based delivery of ABT‐578, a structurally unique macrocyclic lactone. Stainless steel balloon‐expandable stents were coated with thin layer of phosphorylcholine (PC) or PC with ABT‐578 (10 μg/mm). Fifteen juvenile domestic pigs underwent placement of oversized bare metal (n = 15), PC (n = 8), and PC with ABT‐578 (n = 9) stents in the coronary arteries. At 28 days, histology demonstrated similar mean injury scores for the control, PC‐, and ABT‐578‐coated stents. The mean neointimal area (mm2) was significantly reduced for ABT‐578 (1.70 ± 0.47) as compared with PC (2.82 ± 1.24) and control (2.89 ± 1.91) stents (P ≤ 0.05). The 40% reduction in neointimal area resulted in significantly less mean percent diameter stenosis for ABT‐578 (19.4% ± 4.0%) as compared with PC (30.3 ± 12.1 %) and control (29.4% ± 15.5%) stents (P ≤ 0.03). Twelve of the 45 bare metal stent cross‐sections (26.7%) exhibited a giant cell reaction, while none of the sections from the ABT‐578‐eluting stents had a giant cell reaction (P = 0.004). Stent‐based delivery of ABT‐578 via a PC surface coating inhibits neointimal formation at 28 days in the porcine coronary model. Further study is necessary to determine the dose‐response and long‐term effects ABT‐578‐eluting stents in the porcine coronary model.© 2005 Wiley‐Liss, Inc.
Effect of stress on viral–bacterial synergy in bovine respiratory disease: novel mechanisms to regulate inflammation
Authors: Hodgson P. D. , Aich P. , Manuja A. , Hokamp K. , Roche F. M. , Brinkman F. S. L. , Potter A. , Babiuk L. A. , Griebel P. J.
Published: May 2005

The severity of bovine respiratory infections has been linked to a variety of factors, including environmental and nutritional changes, transportation, and social reorganization of weaned calves. Fatal respiratory infections, however, usually occur when a primary viral infection compromises host defences and enhances the severity of a secondary bacterial infection. This viral–bacterial synergy can occur by a number of different mechanisms and disease challenge models have been developed to analyse host responses during these respiratory infections. A primary bovine herpesvirus‐1 (BHV‐1) respiratory infection followed by a secondary challenge with Mannheimia haemolytica results in fatal bovine respiratory disease (BRD) and host responses to these two pathogens have been studied extensively. We used this disease model to demonstrate that stress significantly altered the viral–bacterial synergy resulting in fatal BRD. Functional genomic analysis revealed that BHV‐1 infection enhanced toll‐like receptors (TLR) expression and increased pro‐inflammatory responses which contribute to the severity of a Mannheimia haemolytica infection. TLRs play a critical role in detecting bacterial infections and inducing pro‐inflammatory responses. It is difficult to understand, however, how stress‐induced corticosteroids could enhance this form of viral–bacterial synergy. Nuclear translocation of the glucocorticoid receptor activates cell signalling pathways which inhibit both TLR signalling and pro‐inflammatory responses. The apparent conundrum between stress‐induced corticosteroids and enhanced BRD susceptibility is discussed in terms of present data and previous investigations of stress and respiratory disease. Copyright © 2005 John Wiley & Sons, Ltd.
Xenogenomics: genomic bioprospecting in indigenous and exotic plants through EST discovery, cDNA microarray‐based expression profiling and functional genomics
Authors: John Ulrik P. , Spangenberg German C.
Published: May 2005

To date, the overwhelming majority of genomics programs in plants have been directed at model or crop plant species, meaning that very little of the naturally occurring sequence diversity found in plants is available for characterization and exploitation. In contrast, ‘xenogenomics’ refers to the discovery and functional analysis of novel genes and alleles from indigenous and exotic species, permitting bioprospecting of biodiversity using high‐throughput genomics experimental approaches. Such a program has been initiated to bioprospect for genetic determinants of abiotic stress tolerance in indigenous Australian flora and native Antarctic plants. Uniquely adapted Poaceae and Fabaceae species with enhanced tolerance to salt, drought, elevated soil aluminium concentration, and freezing stress have been identified, based primarily on their eco‐physiology, and have been subjected to structural and functional genomics analyses. For each species, EST collections have been derived from plants subjected to appropriate abiotic stresses. Transcript profiling with spotted unigene cDNA micro‐arrays has been used to identify genes that are transcriptionally modulated in response to abiotic stress. Candidate genes identified on the basis of sequence annotation or transcript profiling have been assayed in planta and other in vivo systems for their capacity to confer novel phenotypes. Comparative genomics analysis of novel genes and alleles identified in the xenogenomics target plant species has subsequently been undertaken with reference to key model and crop plants. Copyright © 2005 John Wiley & Sons, Ltd.
A phylogenomic study of the genus Alphavirus employing whole genome comparison
Authors: Luers Aimée J. , Adams Sandra D. , Smalley John V. , Campanella James J.
Published: May 2005

The phylogenetics of the genus Alphavirus have historically been characterized using partial gene, single gene or partial proteomic data. We have mined cDNA and amino acid sequences from GenBank for all fully sequenced and some partially sequenced alphaviruses and generated phylogenomic analyses of the genus Alphavirus genus, employing capsid encoding structural regions, non‐structural coding regions and complete viral genomes. Our studies support the presence of the previously reported recombination event that produced the Western Equine Encephalitis clade, and confirm many of the patterns of geographic radiation and divergence of the multiple species. Our data suggest that the Salmon Pancreatic Disease Virus and Sleeping Disease Virus are sufficiently divergent to form a separate clade from the other alphaviruses. Also, unlike previously reported studies employing limited sequence data for correlation of phylogeny, our results indicate that the Barmah Forest Virus and Middelburg Virus appear to be members of the Semliki Forest clade. Additionally, our analysis indicates that the Southern Elephant Seal Virus is part of the Semliki Forest clade, although still phylogenetically distant from all known members of the genus Alphavirus. Finally, we demonstrate that the whole Rubella viral genome provides an ideal outgroup for phylogenomic studies of the genus Alphavirus. Copyright © 2005 John Wiley & Sons, Ltd.