bluuebunny/crossref_metadata_2025_split huggingface dataset:
Available Water and Nitrogen Effects on Yield Components and Grain Nitrogen of Zero‐Till Spring Wheat
Authors: Campbell C. A. , Selles F , Zentner R. P. , McConkey B. G. 
Published: July 2010

AbstractStraw yield is important in soil conservation and nutrient cycling. Grain N concentration is of economic importance, and variations in yield components can be used to improve our understanding of grain yield response to environmental stimuli. Therefore, quantifying these responses in relation to soil water and N fertility is of considerable importance. A 9‐yr study was conducted in southwestern Saskatchewan on a medium textured Aridic Haploboroll using zero‐tillage management. We examined the influence of snow trapping and fertilizer management (rate, placement, and time of N application) on hard red spring wheat (Triticum aestivum L.) grown annually. Multiple regression was used with backward elimination to relate straw yield, heads per plant, kernel weight, and grain N concentration to available water use (WU), fall soil NO3−N in 0‐0.6 m depth (SN), rate of urea fertilizer N (FN), years of consecutive cropping (Yr) and several interactions among these variables. Significant (P < 0.0001) meaningful relationships were obtained betwen straw yield (R2 = 0.78, P = 0.001), kernel wt (R2 = 0.81, P = 0.001), heads/plant (R2 = 0.36; P = 0.001) and grain N concentration (R2 = 0.56, P = 0.001) and the independent variables. In this semi‐arid region, WU was by far the most important factor influencing all characteristics. The effect of SN was often more important than that of FN. Further, the advantage of SN over FN increased with years of cropping, possibly reflecting a gradual increase in the N supplying power of this well‐managed soil. Straw yield was related to grain yield. The relationship expressed in kilograms per hectare, was SY = 285 + 0.77 GY + 0.00029 GY2, R2 = 0.85, P = 0.001, n = 1248). Grain N concentration was greater for spring than for fall‐applied N in 5 of 9 yr, and deep banding superior to broadcasting in 1 of 9 yr.
Water Deficit Effects on Osmotic Potential, Cell Wall Elasticity, and Proline in Five Forage Grasses
Authors: Barker D. J. , Sullivan C. Y. , Moser L. E. 
Published: July 2010

AbstractPhysiological responses of forage grasses to water deficit are not well documented, but may be important in determining drought resistance. The objective of this study was to determine the response of osmotic potential, leaf proline concentration, and cell wall elasticity to water deficit for the C4 (warm‐season) grasses ‘Nebraska 54’ indiangrass [Sorghastrum nutans (L.) Nash], ‘Pathfinder’ switchgrass (Panicum virgatum L.), and ‘Pawnee’ big bluestem (Andropogon gerardii Vitman), and the C3 (cool‐season) grasses, ‘loreed’ reed canarygrass (Phalaris arundinacea L.), and ‘Lincoln’ smooth bromegrass (Bromus inermis Leyss.). Other measurements included leaf water potential, soil water content, and osmotic adjustment. A field study at Mead, NE, and a complementary greenhouse study at the University of Nebraska, Lincoln, found osmotic adjustment occurred in response to water deficit for all species, and was greater for C4 than for C3 grasses. Despite less osmotic adjustment, C3 grasses had more elastic cell walls (low modulus of cell wall elasticity), which maintained turgor despite loss of water. Leaf proline concentration averaged 20 times greater in stressed compared to well‐watered plants grown in the greenhouse. Proline accumulation in greenhouse‐grown plants was much larger than observed under field conditions. The physiological role of proline accumulation was uncertain because even dramatic increases in leaf proline concentration were insufficient to influence osmotic potential.
Field Response of Soybean to Nodulation by a Rhizobitoxine‐Producing Strain of Bradyrhizobium
Authors: Vasilas Bruce L. , Furhmann Jeffrey J. 
Published: July 2010

AbstractNodulation by rhizobitoxine‐producing (RT+) strains of Bradyrhizobium japonicum has been shown to decrease shoot growth of green‐house‐grown soybeans. The potential impact of nodulation by a RT+ strain on the productivity of field‐grown soybeans has not been determined. Therefore, a field experiment was conducted for 2 yr on a Matapeake silt loam (fine‐silty, mixed, mesic Typic Hapludults) to determine the response of soybean cv. ‘Forrest’ to nodulation by one RT+ strain (USDA 94). Inoculation treatments were (i) USDA 94, (ii) a mixture of bradyrhizobia indigenous to the field site (Control), and (iii) a combination of Treatments 1 and 2 (USDA 94/Soil). Inoculation treatments were applied to the seed and the seedlings were grown for about 21 d under greenhouse conditions. Pre‐nodulated seedlings were transplanted to 1.8‐m2 field microplots. Inoculation with USDA 94 reduced plant N derived from fixation (as measured by isotope dilution) by 43% relative to the Control (2‐yr mean). Inoculation with USDA 94 decreased seed yield by 38%. Yield reductions were associated with reductions in pod number. The USDA 94 inoculation decreased vegetative growth, delayed the onset of full pod, beginning seed and full seed stages, and doubled the interval between beginning pod and full pod stages. For most of the parameters measured, USDA 94 and USDA 94/Soil treatments produced similar results. This research demonstrated that nodulation by USDA 94 can significantly alter shoot growth and reduce seed yield of field‐grown soybeans.
Logistic Response of Bermudagrass and Bunchgrass Cultivars to Applied Nitrogen
Authors: Overman A. R. , Sanderson M. A. , Jones R. M. 
Published: July 2010

AbstractModels provide a quantitative means to evaluate yield response of forage grasses to applied N and water availability. The objective of this analysis was to estimate model parameters (A, b, c) for bermudagrasses and bunchgrasses grown at the same location and during the same time period. The logistic equation was used to relate annual dry matter production to applied N for three bermudagrasses [Cynodon dactylon L., ‘Coastal’, ‘Alicia’, and ‘Coastcross‐1’] and four bunchgrasses [Eragrostis curvula (Schrad.) Nees, ‘Morpa’ and ‘Renner’ lovegrass; Panicum coloratum L., ‘Selection‐75’ kleingrass, and Cenchrus ciliaris L., ‘Strain 18‐35’ buffelgrass]. Data were from 4 yr of field experiments at Stephenville, TX. Analysis of variance was used to show that the N coefficients b and c were independent of year and climate for each grass, in agreement with recently published results. Applied N required to provide one‐half of maximum yield was approximately 150 kg ha−1 for bermudagrass and 50 kg ha−1 for lovegrass. Variation among years was accounted for in the linear coefficient A, which was then related to rainfall. Bunchgrasses typically had lower A and b, but similar c values compared with bermudagrasses. The logistic model allows estimates of yields in terms of applied N and rainfall, and quantifies the interaction between these two factors. Bermudagrass yielded approximately 45% more dry matter than lovegrass for the same rainfall. Correlation coefficients exceeded 0.95 throughout the analysis.
Soil Temperature, Soil Water, and No‐Till Corn Development Following In‐Row Residue Removal
Authors: Fortin M.‐C. 
Published: July 2010

AbstractIn northern areas where corn (Zea mays L.) is grown, no‐till plants develop more slowly and, consequently, could be more susceptible to soil water limitations than plants under conventional tillage. This study was conducted to determine if removing in‐row residues by pushing them into the interrow can solve problems related to no‐till corn development in droughty soils. Residues were removed to produce a 30‐cm band of bare soil along the corn row. This bare row no‐tillage (BRNT) treatment was compared with conventional tillage (C), regular no‐tillage (NT), and bare no‐tillage (BNT) for plant development, plant height, crop yield, soil water content in the upper soil layers, and seed zone temperature. The BRNT seed zone temperature was higher than that of NT and similar to that of C and BNT from emergence to the V6 stage. Accordingly, BRNT plants reached the V6 stage 1.3 and 3.7 d later than C while NT reached the V6 stage 5.0 and 7.2 d later than C in 1990 and 1991, respectively. In 1991, NT plants were further retarded by hot and dry conditions despite the fact that interrow soil water was higher in treatments with interrow residue cover. Height differences among treatments were related to developmental differences. Despite considerable changes in soil temperature, water, developmental rate, and height of plants among treatments during the vegetative stage, reproductive yield was not affected by tillage and residue treatments.
Post‐Anthesis Nitrogen Loss from Corn
Authors: Francis D. D. , Schepers J. S. , Vigil M. F. 
Published: July 2010

AbstractPublished research has shown relatively large amounts of NH3 being lost from aboveground vegetation during grain development for various grain crops For corn (Zea mays L.), maximum net N accumulation usually occurs during early reproductive development (R1‐R3) and a subsequent decline is often observed. Two recently completed N fertilizer recovery studies on irrigated corn utilizing isotopic techniques were re‐examined to quantify post‐anthesis N losses from aboveground biomass of irrigated corn under different N regimes. These studies were conducted at different sites, in different years, with fertilizer rates ranging from 50 to 300 kg N ha−1. Measured losses of labeled N from aboveground plant material ranged from 7 to 34 kg N ha−1. Isotopic dilution suggests that apparent real N losses from aboveground biomass ranged from 45 to 81 kg N ha−1, assuming there is no selectivity for N source (i.e., 15 N vs. 14N). Plant N losses accounted for 52 to 73% of the unaccounted‐for N in 15N balance calculations. Failure to include direct plant N losses when calculating an N budget leads to overestimation of losses from the soil by denitrification, leaching, and ammonia volatilization. Proper accounting for volatile plant N losses may improve management strategies that affect N fertilizer use efficiencies.
FLOWDATA: Software for Analysis of Infiltration Data from Automated Infiltrometers
Authors: Ankeny M. D. , Prieksat M. A. , Kaspar T. C. , Noh K. M. 
Published: July 2010

AbstractSoil hydraulic properties are quite variable, and characterization of field sites usually requires many measurements. One way to collect the data needed for field site characterization is to use multiple infiltrometers with automated data collection capabilities. Automated infiltrometers use pressure transducers connected to a datalogger to measure cumulative infiltration over time. The FLOWDATA software was developed to reformat, graphically display, and analyze the large well‐structured data sets collected with automated infiltrometers. Program features include interactive editing, graphing, statistical summaries for each infiltration data set, and pooling of estimates from multiple data sets. Inputs required are identification codes, times, transducer voltage readings, and transducer calibration files. Outputs are infiltration rates, and saturated and unsaturated hydraulic conductivities. Program performance is demonstrated with data from a typical field data file.
Sowing Depth and Soil Water Effects on Seedling Emergence and Root Morphology of Three Warm‐Season Grasses
Authors: Roundy Bruce A. , Winkel Von K. , Cox Jerry R. , Dobrenz Albert K. , Tewolde Haile 
Published: July 2010

AbstractGreater seed burial has been suggested as a way to increase the time of water availability to seeds and seedlings in revegetation of semiarid rangelands. The effects of sowing depth on seedling emergence and root development of ‘Vaughn’ side‐oats grama [Bouteloua curtipendula (Michx.) Torr.], ‘A‐130‘ blue panic (Panicum antidotale Retz.), and ‘Cochise’ atherstone Iovegrass (Eragrostis lehmanniana Nees × E. tricophora Coss. & Dur.) were measured in relation to water availability on a sandy loam soil in the greenhouse. Side‐oats grama and blue panic were sown at depths of 0, 10, 20, and 30 mm, while Cochise lovegrass was sown at 0, 5, 10, and 15 mm. Pots were subirrigated every 3 d, on Days 1 and 7 after sowing, or on Day 1 only. Soil water contents in the greenhouse were initially higher and decreased more rapidly than those of field seedbeds. Seedling emergence was generally highest from surface‐sown seeds and decreased with depth of sowing, possibly due to lack of aeration. All three warm‐season grasses elongated their subcoleoptile internodes to place the coleoptilar node and site of adventitious root initiation near the soil surface, regardless of sowing depth. Adventitious roots required 9 to 13 d of available water to initiate. Seminal root growth and depth were not increased with increased sowing depth. Seminal root elongation rates from 5.8 to 8.7 mm d−1 are not fast enough to stay ahead of a typical drying front of 15 to 20 mm d−1 during the summer rainy season on sandy loam soils in southern Arizona. Frequent rainfall is apparently necessary to permit adventitious root development and establishment of these species.
Using GIS Datasets to Classify Maize‐Growing Regions in Mexico and Central America
Authors: Pollak Linda M. , Corbett John D. 
Published: July 2010

AbstractThe environments in which maize (Zea mays L.) germplasm originated and in which it is evaluated can substantially affect results from germplasm evaluations, thus influencing where the germplasm will eventually be used. The adaptation classifications normally used (e.g., temperate, tropical, subtropical, and highland) are imprecise. Our objectives were to (i) apply multivariate statistical techniques to spatial GIS (geographic information system) datasets of agroclimatic data to group similar maize‐growing regions in Mexico and Central America and then (ii) use the groups to refine the mega‐environments developed by CIMMYT maize breeders to help manage their germplasm. Data for this region were extracted from a GIS‐compatible global spatial climate dataset. Variables analyzed (based on long‐term monthly averages) included mean maximum and minimum monthly air temperatures, absolute maximum and minimum air temperatures based on each year's monthly data, mean monthly temperatures and precipitation, total precipitation, and mode of the elevations in the grid. The best grouping of similar regions resulted when cluster analysis on 7 mo of growing season data (April through October) was used to obtain 25 groups. The 25 groups were then classified into 10 maize ecologies corresponding to CIMMYT's mega‐environments. The ecologies included three lowland, three highland, two subtropical, and two transitional from subtropical to highland. The technique will be an important aid in classifying and using northern Latin America's large quantity of diverse maize germplasm.
Nitrogen Fertilization Timing Effect on Wheat Production, Nitrogen Uptake Efficiency, and Residual Soil Nitrogen
Authors: Alcoz Mercedes M. , Hons Frank M. , Haby Vincent A. 
Published: July 2010

AbstractSplit fertilizer N application has been proposed for improving N uptake efficiency in wheat (Triticum aestivum L.) production systems, but results have been inconsistent. In this field study, 75 and 150 kg N ha−1 was applied either all preplant or in two, three, or four split applications based on wheat growth stage (GS) to determine N timing effect on wheat yield and apparent fertilizer N recovery. Vegetative samples were also collected at Feekes GS 4, 6, and 10 to determine treatment effects on tissue N concentration during the growing season. Soil samples were collected after harvest to evaluate residual N quantity and movement in soil relative to N rate and time of application. The soil used was a Fluventic Ustochrept‐Udic Chromustert intergrade. Nitrogen rate and application timing appeared to have less effect than year on yield and N parameters. Significant grain yield increases were achieved with split applications of N fertilizer when N was topdressed at GS 4 or 6 in 1989 as compared with all preplant or application at GS 10. Split N application at GS 10 produced greater grain yield than application at GS 4 or 6 in 1990. Nitrogen uptake efficiency was greatest with 75 kg N ha−1 and split application. Soil NO‐3–N concentration was significantly higher at 150 kg N ha−1 than at 75 kg N ha−1. Significantly lower residual NO‐3‐N with the preplant treatment was not accounted for by greater grain or straw N content.
Accounting for Spatial Yield Variability in Field Experiments Increases Statistical Power
Authors: Scharf Peter C. , Alley Marcus M. 
Published: July 2010

AbstractParametric statistical techniques evaluate treatment significance in field experiments by comparing variability attributed to treatments to variability attributed to random error. In many experiments, a considerable amount of the variability attributed to random error is actually due to large‐scale soil variability that cannot be accounted for by blocking. This variability can, in part, be accounted for by a technique called nearest neighbor analysis, thus reducing the amount of variability attributed to random error; variability attributed to treatments is then larger in comparison, and the statistical significance of treatment effects is increased. Our objective was to evaluate the utility of nearest neighbor analysis in the statistical analysis of a set of field experiments. Four experiments with fall N treatments on winter wheat (Triticum aestivum L.) were analyzed using analysis of variance (ANOVA). According to this analysis, treatment had no significant effect on yield in any of the four experiments. After nearest neighbor analysis was used to remove spatial yield variability from the random error term, ANOVA revealed statistically significant treatment effects in two of the four experiments. Accounting for spatial variability is a practical way to increase the power of ANOVA and accompanying means‐separation techniques when analyzing data from replicated field plot experiments.
Row Spacing and Nitrogen: Effect on Alfalfa‐Bermudagrass Yield and Botanical Composition
Authors: Stringer William C. , Khalilian Ahmad , Undersander Daniel J. , Stapleton Gregory S. , Bridges William C. 
Published: July 2010

AbstractInterseeding perennial legumes into bermudagrass [Cynodon dactylon (L.) Pers.] sods should increase forage quality. Preliminary research revealed that alfalfa (Medicago sativa L.) interseeded into bermudagrass (BG) rapidly reduced BG vigor, possibly because of shading by alfalfa. Grass—legume pastures should contain balanced mixtures for quality maintenance and bloat prevention. It may be possible to manipulate botanical composition with N and row spacing. The objective of this research was to examine effects of these factors on botanical composition and yield of alfalfa‐BG swards. We interseeded alfalfa into ‘Tifton 44’ BG in 20‐, 40‐, and 60‐cm row spacings, and included a non‐interseeded check treatment. Experiments were on Norfolk sandy loam (fine‐loamy, siliceous, thermic Typic Kandiudult) and Cecil sandy clay loam (clayey, kaolinitic, thermic Typic Kanhapludult) sites. Nitrogen was applied at 0, 112, 224, and 448 kg ha−1 yr−1. Yield of BG increased by a factor of 2.06 with 448 kg ha−1 of N, compared with 0 N. Alfalfa increased total yields over BG alone, at all but the highest rates of N. Nitrogen increased yields of interseeded plots an average of 11%. Yield increases from N did not result from increased grass percentage. Increasing row spacing decreased yields of interseeded mixtures, but increasing N rate sometimes compensated slightly for wide rows. Nitrogen had no effect or decreased grass percentage, whereas wide row spacing usually increased the grass component. It appears that alfalfa utilized a significant portion of applied N, and that N will not aid in retaining BG in mixtures. Increasing row spacing will aid in retaining grass in mixture, probably through reduced shading of grass.
Rotation and Nitrogen Fertilization Effects on Changes in Soil Carbon and Nitrogen
Authors: Varvel Gary E. 
Published: July 2010

AbstractLong‐term effects of cropping systems on soil properties, such as organic soil C and N levels, is necessary so more accurate projections can be made regarding the sequester and emission of CO2 by agricultural soils. This information can then be used to predict the effects of cropping systems on both soil degradation, maintenance, or improvement and global climate changes. My objective was to evaluate the effects of crop rotation and N fertilizer management on changes in total soil C and N concentrations that have occurred during an 8‐yr period in a long‐term study in the Western Corn Belt. Seven cropping systems (three monoculture, two 2‐yr, and two 4‐yr rotations) with three rates of N fertilizer were compared. Monocultures included continuous corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and grain sorghum [Sorghum bicolor (L.) Moench]. The 2‐yr rotations were corn‐soybean and grain sorghum‐soybean, and the two 4‐yr rotations were corn‐oat (Avena sativa L.) + clover (80% Melilotus officinalis Lam. and 20% Trifolium pratense). grain sorghum‐soybean and corn‐soybean‐grain sorghum‐oat+clover. Soil samples were taken in the spring both in 1984 and 1992 to a depth of 30 cm in 0‐ to 7.5‐cm, 7.5‐ to 15‐cm, and 15‐to 30‐cm increments. No differences were obtained in 1984, but both rotation and N rate significantly affected total soil C and N concentrations in 1992. The results indicate that C could be sequestered at 10 to 20 g m−2 yr−1 in some cropping systems with sufficient levels of N fertilizer. Greater storage of C in soils suggests CO2 emissions from agricultural soils could be decreased with improved management practices and may in the long term have a significant effect on CO2 in the atmosphere under current climate conditions.
CropSyst: A Collection of Object‐Oriented Simulation Models of Agricultural Systems
Authors: Van Evert F. K. , Campbell G. S. 
Published: July 2010

AbstractSimulation of whole agricultural systems is now widely used in agronomy. Construction and maintenance of the large simulation models required for agricultural systems may benefit from the application of modern programming methods. In particular, object‐oriented programming (OOP) methods claim several advantages over conventional procedural methods. We sought a programming approach that would allow (i) interchanging of component models within and between whole‐system models, (ii) incremental model building without rewriting existing code, (iii) maintenance of more than one model of a component, and (iv) construction of a user‐friendly interface from which all parameters can be assigned and component models run. Here we report results of an experiment in which we used OOP to construct a cropping system model called CropSyst. An OOP analysis of cropping systems led to the abstraction of component systems (objects) with minimal and well‐defined interfaces. Examples of components, or objects, used in CropSyst are Time, Weather, Crop, Soil, Crop residue, Tillage, Erosion, Aphid population, Aphid immigration, Pesticide application, Planting, Crop rotation, and Output. Different versions of CropSyst were implemented and used to simulate production and erosion for cropping systems in eastern Washington, and to simulate yield loss and pesticide dynamics associated with Russian Wheat Aphid infestation. These were constructed from existing objects. Different versions of the Crop object simulated the different crops in a rotation cycle. Parameters were assigned and models were run from a commercially supplied user interface, which was also programmed using OOP. We were able to meet our objectives using OOP, and found it useful for construction and maintenance of agricultural systems models.