bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance and Stability of Brachytic and Normal‐Stemmed Isolines of Soybean
Authors: Lee Suk Ha , Boerma Roger H. , Raymer Paul L. , Ashley Doyle A. 
Published: July 2010

AbstractPlant lodging is a problem in soybean [Glycine max (L.) Merr.] production, particularly in high‐yield environments. The brachytic stem trait (sb1 sb2) reduces plant stature while maintaining the number of nodes for fruiting and may be desirable in the development of lodging‐resistant cultivars. To determine the effects of brachytic stem on seed yield, plant height, and other agronomic traits across a range of environments, this trait was backcrossed into ‘Wright’ and ‘GaSoy 17’, and the near‐isogenic lines (isolines) were evaluated in 57 (Wright) and 36 (GaSoy 17) environments. Averaged across environments, the height of brachytic Wright (B‐Wright) was 56% of its normal‐stemmed isoline and that of brachytic GaSoy 17 (B‐GaSoy 17) was 66% of its isoline. In a combined analysis over environments, brachytic genotypes averaged 37% shorter internode length, 5% fewer nodes, and 7% smaller seed weight than normal‐stemmed isolines. Brachytic and normal‐stemmed isolines did not differ in yield, seed protein concentration, or seed oil concentration. There was a genotype x environment interaction (P < 0.01) for yield for both isoline pairs. Regression analysis of yield stability indicated that the GaSoy 17 isolines were equally stable across environments (similar coefficients and R2 values). For B‐Wright, however, a smaller regression coefficient (b = 0.82 ± 0.07) than Wright (b = 1.07 ± 0.05) and a lower R2 value (70 vs. 89%) suggest that Wright yielded higher in favorable environments and was more stable in yield performance. Plant height of brachytic lines was much less stable than for normal‐stemmed lines. Genotypes with the brachytic stem trait produced yields similar to normal‐stemmed genotypes in environments not highly conducive to lodging. The reduced stability of yield and plant height for brachytic‐stemmed genotypes must be considered (along with the expected increase in yield in lodging‐prone environments) prior to commercial acceptance.
Modified No‐Till Systems for Corn Following Wheat on Clay Soils
Authors: Opoku George , Vyn Tony J. , Swanton Clarence J. 
Published: July 2010

AbstractConcerns about corn (Zea mays L.) grain yield reduction with notill following winter wheat (Triticum aestivum L.) in rotation on clay soils has been a major factor in slowing the rate of adoption of no‐till systems in Ontario. Our objective was to determine conservation tillage and wheat residue management systems that provide favorable seedbed conditions for emergence, growth, and yield of corn following winter wheat on clay soils. Seven tillage and residue management systems (fall moldboard plow, chisel plow, tandem disk, and zonetill, and no‐till bare and with straw baled and not baled) were evaluated in 1994 and 1995 at two locations in Ontario. Fall zone‐till reduced the amount of wheat residues on the soil surface. Wheat residues remaining in late fall with zone‐till, no‐till (baled), and no‐till (not baled) treatments were 3.1, 4.0, and 7.1 Mg ha−1. Volumetric soil moisture levels in the top 15 cm early in the season did not differ among fall tillage treatments, but were all lower than for no‐till with wheat residue. Modifying the no‐till system by adopting fall zonetill or fall tandem disk produced grain yields no different from fall moldboard plow or fall chisel plow treatments, and greater by 5 to 10% than for no‐till with wheat residue. No‐till yield potential was affected by the level of wheat residue present. Completely removing all wheat residue increased no‐till corn grain yields by 0.5 and 0.9 Mg ha−1 compared with baling and not baling straw, respectively. The baled and not‐baled no‐till treatments had the lowest proportion of finer soil aggregates in the seedbed, greatest penetrometer resistance up to the 20‐cm soil depth, slowest corn growth, and lowest grain yield. We recommend zone‐till or tandem disk in the fall for corn production on clay soils following wheat.
Effectiveness of Soil‐Applied Herbicides with Mechanical Weed Control for Conservation Tillage Systems in Soybean
Authors: Hooker David C. , Vyn Tony J. , Swanton Clarence J. 
Published: July 2010

AbstractProducers who adopt conservation tillage systems need information on effective weed control strategies. In 1991 and 1992, various weed control strategies were evaluated in soybean [Glycine max (L.) Merr.] grown with three tillage systems at two locations in southern Ontario. Primary tillage treatments were fall moldboard plowing (MB), fall chisel plowing (CP), and first‐year no‐till (NT). Combinations of mechanical weeding, residual herbicides broadcast at two rates, and a band application of metolachlor (2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl)acetamide) plus linuron (N'‐(3,4‐dichlorophenyl)‐N‐methoxy‐N‐methylurea) were investigated as treatments within each tillage system. Timely rotary hoeing reduced weed numbers in MB and CP treatments, but was not effective in NT. In general, weeds were controlled by residual herbicide plus mechanical treatments (one pass with rotary hoe and two interrow cultivations) regardless of tillage system, or whether herbicides were applied in a band, or broadcast at either reduced or full rates. Herbicides broadcast at reduced rates with no subsequent mechanical weeding controlled weeds in NT; the degree of weed control was inconsistent with location with this weed treatment in MB and CP systems. In general, tillage did not appear to influence the relative proportion of one annual broadleaf weed species over another. However, overall weed populations were lower in first‐year NT than MB or CP tillage systems. Annual broadleaf weeds were effectively managed with reduced herbicide inputs in newly established conservation tillage systems.
Determination of Pasture Biomass Using Four Indirect Methods
Authors: Harmoney Keith R. , Moore Kenneth J. , George J. Ronald , Brummer E. Charles , Russell James R. 
Published: July 2010

AbstractThe most accurate method for determining canopy biomass of pastures for forage availability is by cutting and weighing forage from known areas. Faster methods that require less time and labor would help producers to monitor forage availability in pastures on a daily or weekly basis. Indirect methods rely on calibrations performed on pure or evenly distributed plant compositions to determine forage biomass. However, microclimates developed by varying landscape positions and soil morphological characteristics of pastures may cause uneven plant and species distributions. This study was performed to compare the ability of a modified Robel pole, rising plate meter, canopy height stick, and Li‐Cor LAI 2000 leaf canopy analyzer to determine forage availability in pastures with varying species composition from four areas. Swards consisted of pure warm‐season grass stands, cool‐season grass stands, legume stands, and grass‐legume mixtures. Instrument readings were compared with forage availability determined by clipping and were measured for accuracy, or closeness to clipped weight. For all observations, coefficients of determination (r2), were 0.63, 0.59, 0.55, and 0.32 for the modified Robel pole, rising plate meter, canopy height stick, and leaf canopy analyzer, respectively. For modified Robel pole readings, r2 was highest for observations in red clover (Trifolium pratense L.) (r2 = 0.83), smooth bromegrass (Bromus inermis Leyss.) (r2 = 0.82), and alfalfa (Medicago sativa L. (r2 = 0.76) swards, whereas the rising plate meter r2 values were highest for observations in tall fescue (Festuca arundinacea Schreb.) (r2 = 0.85), alfalfa (r2 = 0.84), and red clover (r2 = 0.73) swards. Grass observations also had their highest r2 values with the modified Robel pole and rising plate meter at 0.63 and 0.59, respectively. The modified Robel pole proved to be the most accurate method used over a variety of species.
Digital Image Correlation Procedure to Characterize Soil Surface Layer Cracking
Authors: Caárdenas‐García Jaime F. , Yao Haigen , Zheng Siding , Zartman Richard E 
Published: July 2010

AbstractThis study was conducted to characterize surface layer cracking in Vertisols by determining surface displacement trends. A disturbed sample from the Ap horizon of a Randall clay (fine, smectitic, thermic Ustic Epiaquerts) was evaluated. Digital image correlation (DIC) used to track the movement of points on the surface as the soil dried and to assess the development of soil surface cracking. Displacement fields among a group of images were obtained by using a cross‐correlation algorithm. The displacement vectors resulting from the analysis of the displaced fields can be used to show cracking patterns on a ground‐up soil sample from a Vertisol before they become visually apparent. Digital image correlation may be used to calculate the deformation of the surface layer with relatively high precision.
Estimating Root Mass in Maize Using a Portable Capacitance Meter
Authors: van Beem Janny , Smith Margaret E. , Zobel Rich W. 
Published: July 2010

AbstractTime and expense are major constraints limiting the detection of genotypic differences in the length, structure, and growth rate of root systems in the soil. Recent development of a hand‐held capacitance meter could enable the routine quantification of root mass. The objective of this study was to determine the accuracy with which a BK Precision 810A capacitance meter can estimate root fresh mass in maize (Zea mays L.) using a technique that allows a rapid and noninvasive capacitance reading. The capacitance meter measured root capacitance of maize grown under greenhouse (8 genotypes) and field (6 genotypes) conditions. After the capacitance readings, 14 plants per genotype were uprooted, roots were washed thoroughly, and root fresh mass was obtained. The statistical relationship between capacitance and root fresh mass in greenhouse experiments was significant early in the growth season for all genotypes (r2 = 0.73, P < 0.001), and significant only late in the growth season for inbreds (r2 = 0.56, P < 0.001). Field studies showed that capacitance and root fresh mass were statistically correlated for all genotypes at flowering (r2 = 0.69, P < 0.001). In conclusion, capacitance meters equipped with a clamp for rapid attachment to the plant may facilitate the nondestructive identification of genotypes with root characteristics that confer adaptation to various environments. Conditions for accurate capacitance measurements included a moist medium around the plant's root system and a consistent placement of the electrode at 6 cm above the crown.
Establishment of Switchgrass and Big Bluestem in Corn with Atrazine
Authors: Hintz Roger L. , Harmoney Keith R. , Moore Kenneth J. , George J. Ronald , Brummer Edward C. 
Published: July 2010

AbstractSwitchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) provide abundant forage for livestock and wildlife during hot summer months when cool‐season grass species may decline in production. Little biomass production for grazing may result during warm‐season grass establishment because of weed competition. Chemical methods of weed control are now limited, because application of atrazine [6‐chloro‐N‐ethyI‐N'‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] to switchgrass and big bluestem is no longer allowed according to the label. Using corn (Zea mays L.) as a companion crop could provide potential for high biomass production during warm‐season grass establishment, and allow the use of atrazine for weed control. This study investigated the ability of switchgrass and big bluestem to establish in a corn companion crop. The effects of corn hybrid (short‐ vs. long‐season), population density, row spacing, and harvest date on switchgrass and big bluestem stands and on corn production were quantified. Establishment of switchgrass and big bluestem in corn was successful. Switchgrass mean stands were 26.3 plants m−2 in 1995 and 46.4 plants m−2 in 1996. Big bluestem stands were similar to switchgrass in 1995 (31.7 plants m−2), but were much lower in 1996 (5.2 plants m−2). Long‐season corn hybrids and higherdensity corn populations increased corn silage and grain yield without reducing warm‐season grass stands. Within a season, no difference existed between corn grain yields when grown with either switchgrass (6.7 Mg ha−1 in 1995, 5.3 Mg ha−1 in 1996) or big bluestem (6.9 Mg ha−1 in 1995, 5.7 Mg ha−1 in 1996). Silage dry matter yield was not different between corn grown with switchgrass (12.6 Mg ha−1 in 1995, 16.1 Mg ha−1 in 1996) and corn grown with big bluestem (13.1 ha−1 in 1995, and 16.6 Mg ha−1 in 1996) for a given year. Switchgrass and big bluestem grown in corn with atrazine reduced land production losses during the establishment year, yet allowed adequate establishment of these grasses for future forage production.
Apparatus for Dissecting Stalks to Evaluate Stem Borer Insect Resistance in Maize
Authors: Kreps Ralph C. , Klein Dietrich , Melchinger Albrecht E. 
Published: July 2010

AbstractMeasuring tunnel length in stalks is a common method for evaluating resistance against European corn borer (Ostrinia nubilalis Hübner) in maize (Zea mays L.). Infested plants are dissected and tunnel length, attributed to feeding of corn borer larvae, is measured. This is laborious and time‐consuming, thus restricting the number of genotypes that can be evaluated for resistance in breeding programs. An apparatus built mostly of polyvinylchloride (PVC) and spring steel was constructed for dissecting maize stalks. Stalks are pushed by hand through the apparatus and are thus split apart. This apparatus dissects the stalk into two equal parts for measuring stem borer resistance in maize and reduces the time spent for splitting a stalk by =50% compared with conventional methods. The cutter ensures no escapes in investigating tunnel lengths.
Response of Spring Wheat to Nitrogen Fertilizers of Different Nitrification Rates
Authors: Goos R. Jay , Schimelfenig Julie A. , Bock Bert R. , Johnson Brian E. 
Published: July 2010

AbstractHydroponic and greenhouse studies have shown that grain yields of wheat (Triticum aestivum L.) are maximized when the N supply contains a mixture of NH4 and NO3. Tillers per plant is the yield component most commonly increased by mixed N nutrition in greenhouse studies. The objective of this study was to evaluate, under field conditions, the response of ‘Butte 86’ spring wheat to N sources differing greatly in nitrification rate. Nitrogen was applied at 0 or 112 kg N ha‐1; the N sources were calcium nitrate (CN), urea, ureadicyandiamide (DCD), 0.1‐g urea granules, and 0.1‐g urea–DCD granules. Six field trials were performed. Topsoil (0–15 cm) analysis of fertilized plots during tillering indicated a wide range of mineral N contents (19–101 mg N kg‐1) and of NH4:NO3 mole ratios (0.04–2.06). Correlation analyses suggested that tillering was sensitive to the total mineral N supply, but quite insensitive to the NH4:NO3 ratio in the topsoil. Vegetative growth and N uptake were generally lower for CN than for the other N sources. At some locations, more heads per square meter at harvest were observed with the slower‐nitrifying N sources. Grain yields were increased by N fertilization, but significant differences between N sources were not generally observed. For both years of the study, the 0.1‐g urea‐DCD granules gave the highest N uptake efficiency. However, the dramatic responses in growth, tillering, or grain yield routinely observed with mixed N nutrition in hydroponic or greenhouse studies could not be duplicated in the field.
Fertility Gradients in Naturally Formed Terraces on Honduran Hillside Farms
Authors: Walle Robert J. , Sims Brian G. 
Published: July 2010

AbstractDeposition of eroded sediment within soil conservation barriers may create a gradient of soil properties. Our objective was to determine the presence of soil fertility gradients in the naturally formed terraces of two representative conservation practices; contour grass barriers and stone walls. Soil samples were taken at five slope positions to depth of 20 cm, divided into 5‐cm sections, with three replicates (60 samples per location). Samples were analyzed for texture, total Kjeldahl N, organic matter, and extractable P, K, Ca, and Mg. For both sites, the upper slope positions were lower in soil organic matter, nutrients, and silt than the lower positions. Within stone barriers, the silt fraction and extractable P contents showed gradients, with three of five positions different. Within grass barriers, a gradient was present for clay, with three of five positions different. Organic matter and Ca showed distinct gradients, with all positions different, increasing downslope. A position × depth interaction for organic matter was detected, showing surface removal and deposition along the lower slope positions. Identification of fertility gradients may lead to improved cropping systems and fertilizer management and to refinement of agronomic research on hillside farms.
Management Effects on Herbage Yield and Botanical Composition of Rhizoma Peanut–Mixed Grass Associations
Authors: Valencia E. , Sollenberger L.E. , Kunkle W.E. , Williams M. J. , Chase C. C. , Hammond A. C. , Kalmbacher R.S. 
Published: July 2010

AbstractBroadleaf weeds invade rhizoma peanut (Arachis glabrata Benth.) (RP) stands as they age, possibly because of decline in associated grasses, particularly bahiagrass (Paspalum notatum Flügge). Our objective was to assess the effect of spring N fertilization and summer stocking rate (1.5 vs. 2.5 animals ha−1; Exp. 1) or spring N fertilization and presence or absence (no grazing until July) of spring grazing (Exp. 2) on the herbage yield and botanical composition of mixed RP‐grass swards. In both experiments, pastures were fertilized with either no N (N‐0) or 35 kg ha−1 of N (N‐35) in March or early April for 3 yr. Sward herbage mass (Mg ha−1) and botanical composition were assessed in spring (April), summer (July), and fall (October) of 1995 and 1996 and spring of 1997. In Exp. 1, stocking rate did not affect herbage mass or botanical composition, but N fertilization did. By spring 1997, there was an eight percentage unit increase in grass contribution (0.30 Mg ha−1 increase in dry matter) and a trend for greater decline in RP (five percentage units, but no change in RP dry matter) for N‐35 vs. N‐0. Other forbs, Mexican tea (Chenopodium ambrosoides L.), and cogongrass [Imperata cylindrica (L.) Räusch.] were not affected by N rate. Similar changes in herbage mass and RP percentage were noted for Exp. 2, but there was a stocking rate × N fertilization interaction for grasses because the percentage increase in grass was greatest when N was applied and grazing deferred in the spring. Forb content of the sward was not affected by N fertilization or spring grazing. Our results show that grass yield and content of RP‐grass swards can be manipulated by N fertilization and deferral of spring grazing, but for the limited time period studied (3 yr), increased grass presence was not sufficient to inhibit encroachment of weedy forbs.
Productivity, Botanical Composition, and Nutritive Value of Swards Including Forage Chicory
Authors: Belesky David P. , Fedders James M. , Turner Kenneth E. , Ruckle Joyce M. 
Published: July 2010

AbstractPure stands of ‘Grasslands Puna’ chicory (Cichorium intybus L.) are productive and responsive to N fertilization in the eastern USA. We conducted a field experiment for 3 yr to investigate productivity and nutritive value of swards including chicory, orchardgrass (Dactylis glomerata L.), and birdsfoot trefoil (Lotus corniculatus L.) as a function of clipping frequency (3‐ and 6‐wk intervals). Each treatment was replicated three times on an upland site of Dekalb series soil (loamy‐skeletal, mixed, subactive, mesic Typic Dystrochrept). Modest rates of N, P, and K were applied annually. Herbage mass, botanical composition, in vitro organic matter disappearance (IVOMD), and crude protein (CP) were determined. Cumulative herbage yield was not influenced by initial sward composition with chicory, chicory‐orchardgrass, and chicory–orchardgrass–trefoil averaging 6.8 Mg ha−1 during a growing season. Clipping frequency influenced yield with canopies clipped at 6‐wk intervals producing 26% more herbage than those clipped at 3‐wk intervals. Growth rates of canopies clipped at 6‐wk intervals averaged 51 kg ha−1 d−1 early in the growing season, suggesting that swards including chicory would be responsive to nutrient inputs and where rapid herbage regrowth and nutrient use by the growing crop are needed. Chicory declined in swards with time, regardless of initial sward composition or clipping frequency. Fluctuations in IVOMD and CP were related to changes in sward composition arising from the interaction of time and clipping frequency. Including orchardgrass and trefoil retarded invasion of less desirable species and so provided a means to control overall sward productivity and herbage composition.
A Comparison of Several Methods for Evaluating the Potassium Status of Some Mississippi Soils
Authors: Nelson L. E. 
Published: July 2010

AbstractPotassium was extracted from soils by growing five sunflower plants (Helianthus annuus L. Var. Mammoth Russian) in 500 g. of soil in the greenhouse for 10 weeks. Adequate fertility was provided by adding periodically in small aliquots 1,400 ml. of a nutrient solution complete except for K. In preliminary experiments the effects of length of cropping period, addition of fertilizer K, and day length and temperature were studied.Seventeen representative Mississippi soils were obtained, and total K removal by sunflower was compared to removal by various chemical methods. Chemical methods compared were exchangeable K by N NH4OAc, 0.5N NH4Cl in 0.25N HCl and 0.5N HCl for 15 minutes, and K released by boiling N NHO3, heating to 500° C., and continuous percolation with distilled water. The best correlations were obtained with those methods measuring exchangeable K.In another experiment correlation coefficients between K extracted by sunflower and exchangeable K by N NH4OAc for 29 surface soils and 22 subsoils were 0.899 and 0.928, respectively. The same correlation for upland surface soils was 0.977; for terrace and bottom surface soils, 0.929.A Kaufman sandy loam, continuously fertilized for 30 years with a complete fertilizer was found to accumulate both exchangeable and nonexchangeable K. The uptake of K by sunflower correlated equally well with K extracted by N NH4OAc or boiling N HNO3.
Maintaining High Soil Nutrient Levels for Greenhouse Tomatoes Without Excess Salt Accumulation
Authors: Lucas R. E. , Wittwer S. H. , Teubner F. G. 
Published: July 2010

AbstractExperimental and commercial plantings of greenhouse tomatoes received supplemental fertilizers in the form of KH2PO4, (NH4)2HPO4, KNO3 and NH4NO3 in quantities greater than normally applied. Monthly changes in soil nutrient levels and soluble salt contents were determined and crop behavior observed. A total of 2,922 pounds of nitrogen, 3,054 pounds of P2O5, and 4,662 pounds of K2O per acre were applied during two growing seasons in experimental plantings at the Michigan State University. Soil tests near the end of the growing season for the second year showed 10 pounds of nitrate‐N, 188 pounds of P, and 402 pounds of K per acre by the Spurway “active” method. The soluble salt reading for a 1:2 soil/water mixture was 28 × 10‐5 mho. Yields up to 100 tons of fruit per acre were harvested resulting in total crop removal of 350, 105, and 580 pounds per acre of nitrogen, phosphorus, and potassium, respectively. Cooperative studies were conducted with seven commercial growers. The fertilizer program followed closely that used at the University. Results of soil tests and soluble salt readings were similar to those obtained at the University greenhouse.