bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seed Yield Response of Three Switchgrass Cultivars for Different Management Practices1
Authors: Kassel P. C. , Mullen R. E. , Bailey T. B. 
Published: July 2010

AbstractSwitchgrass (Panicum virgatum L.) is a valuable warm‐season native forage grass in Midwest grazing systems prompting interest in seed production to obtain adequate amounts of seed for planting purposes. Switchgrass seed production studies, however, have been primarily conducted in the Great Plains states. This study was conducted to evaluate cultivar response to row spacing and N fertilization for increasing seed yields in a more humid area of the species' natural adaptation. ‘Cave‐in‐Rock’ (C), ‘Blackwell’ (B), and ‘Pathfinder’ (P) switchgrass were established on a Webster loam (fine‐loamy, mixed, mesic Typic Haplaquoll) soil near Ames, IA, in 1978 in 20‐, 60‐, and 100‐cm rows and fertilized with N at 0, 90, and 180 kg ha−1 in 1979 and 1980. Seed yield and selected seed yield components were measured in 1979 and 1980. Seed yields averaged over 2 years, three N levels and three row spacings were 908, 319, and 388 kg ha−1 for C, B, and P, respectively. Greater lodging resistance, and greater seed yields in response to increased N level and decreased row spacing, contributed to the significantly greater seed yields of C. Seed yields of B and P were similar for all N and row‐spacing treatments. Cultivar rankings in percent fertile tillers varied between years. Inflorescences per unit area did not differ among cultivars, but total seed weight infloresence−1 averaged over years was 268 g for C, which was 54 and 40% greater than for B and P, respectively. Total seed weight inflorescence−1 seemed to be the most important seed yield component, followed by 100 seed weight for explaining seed yield differences among cultivars. Cave‐in‐Rock showed superior lodging resistance and a greater potential for increased seed production in narrow rows and at higher N levels in 2‐ and 3‐year‐old stands. Results showed that N management and row spacing of young stands of switchgrass grown for seed production in the humid Midwest varied according to the cultivar used. Cultivar susceptibility to lodging may be the most limiting factor to obtain high seed yields of some cultivars in the more humid areas of natural adaptation of switchgrass.
Effects of N and Growing Season on Root‐Rhizome Characteristics of Turf‐Type Bermudagrasses1
Authors: Horst G. L. , Baltensperger A. A. , Finkner M. D. 
Published: July 2010

AbstractRoot‐rhizome growth responses of bermudagrasses (Cynodon spp.) in relation to shoot growth interactions with the environment and cultural systems are not well understood. Effects of four N levels on the root‐rhizome organic matter, root viability, and turf color response of five bermudagrass cultivars grown on a Thermic, Typic, and Torrifluvent soil, were determined in the field for two spring shoot initiation periods. Significant differences in rate of decline during spring and increase during the summer growing season in root‐rhizome organic matter were observed for ‘Common’, ‘Tifgreen’, ‘Santa Ana’, ‘FB‐49’, and ‘Texturf‐10’ cultivars. ‘Tifgreen’ was the most responsive and ‘Common’ the least to changes in season and fertilizer N levels. Root viability scores of all cultivars increased during the spring of 1981, declined slightly during the summer of 1981, and declined moderately from 3.5 to 2.7 during spring 1982. Nitrogen application reduced the rate of decline in spring 1982. There was no significant interaction of bermudagrass cultivar × N level for root‐rhizome organic matter, visual root viability, or turf color.
Early‐, Mid‐, and Late‐Spring Establishment of Switchgrass at Several Seeding Rates1
Authors: Vassey T. L. , George J. R. , Mullen R. E. 
Published: July 2010

AbstractConcerns of forage producers about seed cost and difficult stand establishment have limited the popularity and use of switchgrass (Panicum virgatum L.) as a summer forage alternative in the humid northern USA. ‘Cave‐in‐Rock’ switchgrass was seeded with atrazine (2‐chloro‐4‐ethylamino‐6‐isopropyl amino‐1,3,5‐triazine) for weed control in 1981 and 1982 on a Webster‐Nicollet soil complex (fine‐loamy, mixed, mesic, Typic Haplaquoll‐Aquic Hapludoll) at three seeding dates (April, May, and June) and five rates, ranging from 3.4 to 16.8 kg pure live seed (PLS) ha−1. Precipitation patterns primarily accounted for differences in mean seedling numbers of 27.8,13.0, and 28.0 seedlings m−1 of row for April, May, and June seeding dates, respectively. Mean tiller numbers of 118 m−1 in 1981 and 131 m−1 in 1982 suggest that tillering compensated for observed differences between years in initial seedling number, and producers should not hastily attempt to reestablish new seedings which initially appear to be marginal. Greater seeding rates increased seedling number, tiller number, and forage dry matter (DM) yields, but slightly decreased forage in vitro dry matter disappearance (IVDMD) and crude protein (CP). Seeding date had a greater effect than seeding rate on switchgrass forage yield and quality. Seeding‐year forage DM yields were 8.5, 6.5, and 4.5 Mg ha−1 for April, May, and June seedings, respectively. Forage IVDMD and CP concentrations were greatest for June (619 and 120 g kg−1, respectively) and least for April (524 and 84 g kg−1, respectively) seeding dates. Results suggest that highly productive switchgrass stands can be obtained during the establishment year with mid‐April to early May seeding dates at rates of only 3.4 kg PLS ha−1 when atrazine is used for weed control.
Soybean Irrigation Serially Timed During Stages R1 to R6. I. Agronomic Responses1
Authors: Kadhem F. A. , Specht J. E. , Williams J. H. 
Published: July 2010

AbstractPrevious research has shown that irrigation timing during the reproductive development of soybean [Glycine max (L.) Merr.] J genotypes is a crucial determinant in ultimate yield response. To obtain more detailed information on this relationship we evaluated the agronomic responses of 16 soybean cultivars to nine irrigation treatments in a 3‐year field experiment. The experiments were conducted in 1980, 1981, and 1982 near Mead, NE on a Sharpsburg silty clay loam (fine, montmorillitic, mesic Typic Arguidoll). In treatments T1 thru T7, only a single irrigation was applied, which coincided with the average R stages 1.1, 2.5, 3.7, 4.7, 5.6, 5.9, and 6.4, respectively. “Check” treatments included T0, which was not irrigated, and T8, which received a total of seven irrigations coincident with those for T1 thru T7. Averaged over years and cultivars, the seed yield responses (kg/ha) were: T0: 3470c, T1: 3595abc, T2: 3530bc, T3: 3740a, T4: 3670ab, T5: 3630abc, T6: 3575bc, T7, 3560bc, and T8: 3540bc. The irrigation treatment X cultivar interaction was significant, primarily because T3 (R3.7) or T4 (R4.7) generally resulted in the highest yields for indeterminate cultivars, whereas T8 resulted in the highest yields for determinate cultivars. Averaged over irrigation treatments and years, the determinate cv. Hobbit was the highest yielding, both with and without irrigation. Significant increases in plant height, nodes/plant, and lodging occurred with the T1, T2, T3, and T8 treatments, but only with the indeterminate cultivars. Precise irrigation timing and proper cultivar choice seem to be crucial if high yields with minimum lodging are to be attained.
Equivalent Wind‐Erosion Protection from Selected Growing Crops1
Authors: Armbrust D. V. , Lyles Leon 
Published: July 2010

AbstractThe wind erosion equation, which estimates annual potential erosion, requires that all vegetation (dry weight per area) be expressed as a small grain equivalent (SG)e. Wind‐tunnel tests were used to determine that equivalent for five growing crops. These are corn (Zea maysL.), cotton (Gossypium hirsutumL.), grain sorghum [Sorghum bicolor(L.) Moench], peanuts (Arachis hypogaeaL.), and soybean [Glycine max(L.) Merr.] in rows both perpendicular and parallel to flow. Compared with the small grain standard, all the growing crops evaluated in rows perpendicular to flow effectively prevented erosion. Because measured or estimated amounts of aboveground biomass are needed in determining (SG)es, simple power equations relating biomass to plant height were developed. For short‐term application of the wind erosion equation by crop stage period or in models with daily time steps, an equation was derived for calculating (SG)e from time‐after‐emergence growth curves.
Effect of Potassium Fertilizers on Malting Barley Infected with Common Root Rot1
Authors: Timm C. A. , Goos R. J. , Johnson B. E. , Sobolik F. J. , Stack R. W. 
Published: July 2010

AbstractMalting barley (Hordeum vulgareL.) in North Dakota has a history of yield and quality responses to small additions of KCl fertilizer on soils with ample native supplies of exchangeable potassium (K). Five field experiments were established in central or western North Dakota in 1983 to determine if a chloride (Cl)‐induced repression of common root rot, incited by Cochliobulus sativus, was a possible explanation for these past responses. The soils were fine loamy Haploborolls, Argiborolls, or Haplaquolls with greater than 800 kg K ha−1exchangeable K in the plow layer. Experimental design was a factorial combination of two K rates, 23 and 94 kg K ha−1, by two K sources, KCl and K2SO4, plus a control treatment. A randomized complete block design with five or six replicates was employed. Fertilization with KCl significantly decreased root rot incidence at the boot stage at two of five sites and significantly decreased disease severity at the dough stage at three of the five sites. The high rate of KCl visually reduced the severity of spot blotch symptoms on the flag leaves at one site. Nitrate concentrations in plant foliage tended to be depressed at the highest rate of KCl. Chloride concentrations in plant foliage were dramatically increased by KCl application, although concentrations of Cl in control treatments appeared adequate enough to preclude an actual Cl nutritional deficiency. Grain yields were significantly increased by the high rate of KCl at one site. Fertilization with K2SO4significantly increased disease severity at two sites but otherwise had no effect on disease incidence, severity, or grain yield. This research substantiated that Cl‐induced disease repression may explain the history of KCl response in North Dakota, but the reason for this effect is not known.
Potential Yield Response of Corn to Treatments that Conserve Fertilizer Nitrogen in Soils1
Authors: Blackmer A. M. 
Published: July 2010

AbstractRecent 15N‐tracer studies have provided evidence that a substantial portion of the fertilizer N applied for corn (Zea mays L.) production in Iowa may be lost by leaching and (or) denitrification before plants have an opportunity to utilize this N. Because this finding seems contradictory to the results of studies showing that corn yields usually are not increased significantly by treatments known to reduce these losses, a study was conducted to assess the sensitivity of yield response measurements for evaluating the cost‐effectiveness of using treatments that prevent losses of N from soils. Models were developed from responses observed to N fertilizers in the long‐term crop rotation experiments conducted at various locations in Iowa. These models were used to identify combinations of conditions (rates of N application, percentages of fertilizer N saved by the treatment, and sufficiency levels of soil‐derived N) that could be expected to cause statistically significant yield increases from ideal treatments in studies having various levels of precision. Ideal treatments were considered to be 100% effective at preventing losses of fertilizer N and to have no effects other than increasing the availability of fertilizer N to plants. The results suggest that many experiments to evaluate the cost‐effectiveness of treatments that prevent losses of fertilizer N have been conducted under conditions where statistically significant yield responses could not have been expected, even if the treatments were cost‐effective for the crop producer. This finding indicates a need to reevaluate the methodology commonly used to evaluate the cost‐effectiveness of using treatments that reduce losses of fertilizer N from soils.
Irrigation and Planting Date Effects on Soybean Grown on Clay Soil1
Authors: Heatherly L. G. , Elmore C. D. 
Published: July 2010

AbstractIn the southern Mississippi River alluvial plain, adverse weather conditions and the time required for seedbed preparation can often cause delays of 2 to 3 weeks in planting soybean [Glycine max (L.) Merr.] on fine‐textured soils. Because about 2.6 million ha of these soils are planted to soybean, we conducted field experiments in 1980, 1981, and 1982 on Sharkey clay (Vertic Haplaquept, very‐fine, montmorillonitic, thermic) to determine if yields and yield components of mid May (early) and late May or early June (late) plantings would be similarly affected by irrigation. Plantings of ‘Bedford’ and ‘Bragg’ or ‘Braxton’ were made each year and furrow irrigation was initiated at growth stage R1 (I) and continued through stage R6 on designated plots. A nonirrigated (NI) treatment received only rainfall. Planting date did not significantly affect yield in the NI plots in any year, although the trend each year was toward higher yields from the late plantings. With the I plots, seed yields from the early plantings of 1980,1981, and 1982 averaged 65,370, and 475 kg ha−1 more than from the later plantings, respectively, with the increase in 1982 being significant (P = 0.02). Irrigation of the early planting increased average yields by 1970,2020, and 1490 kg ha−1 in 1980,1981, and 1982, respectively; with the late planting, yield increases averaged 1730,1285, and 975 kg ha−1 for the same years. Increased number of seed was responsible for most or all of the yield increases resulting from irrigation. Irrigation of both plantings essentially ensured canopy closure of all cultivars. These results indicate that maximum benefit derived from irrigation applied to soybean grown on a clay soil can be realized if plantings are made in mid‐May.
Leaf Number at Topping and Yield, Grade Index, and Leaf Chemistry of a Mammoth‐Type Tobacco1
Authors: King Mark J. 
Published: July 2010

AbstractTobacco (Nicotiana tabacum L.) cultivars containing a mammoth gene have not been evaluated at leaf numbers greater than 18 to 20 leaves per plant. In addition, they have not been evaluated with respect to potential for mechanical topping. Flue‐cured tobacco cultivar NC 22NF containing the mammoth gene, was grown in 1982, 1983, and 1984 at Blackstone, VA. Plants were topped (apical meristem removed) to determine the effect of leaf number per plant on yield, grade index, and leaf chemistry at constant soil fertility. Leaves remaining on the plant after topping were 14, 18, 22, and 26 per plant. Yield increased with leaf number. This study demonstrated that the accepted practice of topping at 18 to 20 leaves may be extended to 26 leaves, increasing yield and value with no detrimental alteration in leaf chemistry or decline in leaf grade index. The lack of difference in grade index compared to earlier studies may be due to the different genomes. In a duplicate set of treatments, four additional leaves per plant were allowed to develop before being removed to study the effects on yield, grade index, and leaf chemistry at 14, 18, 22, and 26 leaves per plant. The delay in topping until four additional leaves were produced did not significantly decrease yield, grade index, or leaf chemistry and may be advantageous for mechanical topping.
Phosphorus Uptake from Soil Layers Having Different Soil Test Phosphorus Levels1
Authors: Pothuluri J. V. , Kissel D. E. , Whitney D. A. , Thien S. J. 
Published: July 2010

AbstractThe effect of available P in subsoil on plant uptake of P from surface soil layers and consequently on fertilizer recommendations is largely unknown. Our objective was to determine how much P may be removed by crops from subsurface soil layers and how the subsurface P level influences crop drawdown of P from the surface layer. Soil columns were prepared that contained all four possible combinations of low or high P levels in the surface soil and low or high P levels in the subsurface layer. The soil used was a Farnum fine sandy loam (fine‐loamy, mixed, thermic Pachic Argiustoll). Phosphorus removal was monitored by growing hybrid sorghum‐sudangrass [Sorghum bicolor (L.) Moench cv. ‘Honey Chow’] 84 days with an intermediate harvest after 35 days. Compared to when both the surface and subsurface layers had low P levels, P uptake increased when either or both layers had high P levels. Root growth and morphology responded to the P level of the soil layers. For all conditions, P uptake demonstrated a high correlation (R2=0.94) to an accessibility factor defined as the product of the available P level and root length summed for both soil layers. Comparing ratios of crop P removal to the change in soil test showed that P drawdown from the surface layer was reduced when the P‐supplying capacity of the subsurface layer was high. We concluded that available P in the subsurface layer can supply P to the crop, especially if the surface layer cannot supply sufficient P to meet crop demand. These results suggest that subsoil fertility should be considered in evaluating P available to crops and in estimating crop drawdown of available P.
Forage Quality Responses of an Aeschynomene‐Limpograss Association to Grazing Management1
Authors: Sollenberger L. E. , Quesenberry K. H. , Moore J. E. 
Published: July 2010

AbstractLow crude protein concentration (CP) in limpograss [Hemarthria altissima (Poir.) Stapf et C.E. Hubb.] forage may limit the performance of grazing animals. Aeschynomene (Aeschynomene americana L.) is a legume that has potential with limpograss. Effects of grazing management on aeschynomene, limpograss, and total canopy forage quality were measured on a sandy, siliceous, hyperthermic UItic Haplaquod in 1983 and 1984. Experimental variables were (i) limpograss stubble height when aeschynomene was seeded, (ii) legume seedling growth stage when early season grazing of limpograss ended, and (iii) aeschynomene height when summer grazing was initiated. After initiation of summer grazing, all pastures were grazed rotationally every 5 weeks. Aeschynomene leaf had CP and in vitro digestible organic matter concentrations (IVDOM) of approximately 250 g kg−1 DM and 700 g kg−1 OM, respectively. Legume leaf quality was minimally affected by grazing management, but stem quality and leaf/stem ratio decreased as initiation of grazing was delayed. Limpograss CP was generally less than 40 g kg−1 DM. Depending on year and grazing treatment, 8 to 23% aeschynomene was required in herbage accumulated for the CP of herbage consumed to be 70 g kg−1 DM or higher. When limpograss was grazed for 2 weeks after aeschynomene seedlings exserted two true leaves, grass competition to the establishing legume was reduced, percentage legume in the sward was increased, and CP in herbage consumed was maximized. The IVDOM of total herbage accumulated decreased linearly as initiation of grazing was delayed. Seasonal consumption of DOM was greater in treatments where grazing was initiated at 0.20 instead of 0.60 or 0.80 m, despite OM accumulation being greater for the taller initiation heights. Peak legume production occurred in late summer when limpograss quality was low, and these data suggest that incorporation of aeschynomene into grass swards may improve animal performance during this period.
Spring Grazing Effects on Components of Winter Wheat Yield1
Authors: Sharrow S. H. , Motazedian I. 
Published: July 2010

AbstractLivestock grazing of cereal grain crops during the early portion of their growing cycle is practiced to some degree in many parts of the world. While a substantial body of literature relating grain yields to defoliation practices has been accumulated, most of this work lacks detail concerning the effects of grazing on individual components of plant yield. Reports of grazing effects on grain yield have been quite variable, ranging from substantial decreases to modest increases in grain yield. Understandably, many grain producers are confused about the exact impact that livestock grazing has on their grain crop. The effects of a single intense March‐grazing by sheep, on the components of biomass yield in 'Yamhill' soft white winter wheat (Triticum aestivum L. em Thell.) were evaluated near Corvallis, OR, during the 1979‐to‐1981 harvest years. Grazing increased total plant biomass yield each year. The greatest increase was in the grain component, which averaged 16% greater on grazed than on ungrazed plots 'during the 3 yr of the study. Contrary to widely held opinion, grazing had no effect on the number of fertile flower heads produced by the crop. Likewise, grazing did not affect either the number of seeds produced per spikelet or the average seed weight. Increased grain yield on grazed plots largely resulted from an increased number of fertile spikelets produced per wheat head on those plots. These data suggest that components of wheat grain yield that are determined prior to tiller elongation may respond to grazing management.
Volatilization of Ammonia from Granular and Dissolved Urea Applied to Turfgrass1
Authors: Titko Steve , Street John R. , Logan Terry J. 
Published: July 2010

AbstractUrea, applied in either granular or dissolved form, is a commonly used N fertilizer source for turfgrass, and volatilization of NH3 produced by urea hydrolysis is considered to be a major contributor to reduced N fertilizer utilization by established turf. Ammonia volatilization losses from urea applied to turfgrass were studied in a controlled environment chamber. Kentucky bluegrass (Poa pratensis L., var. Merion) sod was placed on a Crosby silt loam soil (fine, mixed, mesic Aerie Ochraqualfs) in 17.5‐L plastic containers with surface areas of 434 cm2. Covers fitted to the containers had intake and exhaust ports such that air could be passed over the sod and NH3 collected in a boric acid trap. Experiments were conducted to examine the effects of temperature, relative humidity, wetting and drying cycles, and irrigation on NH3 loss from surface‐applied urea. Ammonia losses were higher from granular than from dissolved urea in all cases, except where urea application was immediately followed by a 25.4‐mm irrigation: Ammonia loss from granular and dissolved urea increased as temperature increased from 10 to 22.2°C, but there were no significant effects on NH3 loss as temperature increased from 22.2 to 32.2°C. Ammonia losses from dissolved urea at 68% R.H. were greater than losses at 31% R.H., but NH3 loss from granular urea was not significantly affected by relative humidity. Ammonia losses increased rapidly following periodic wetting of the turf fertilized with dissolved urea. Irrigation (25.4 mm) following urea application decreased NH3 losses from both dissolved and granular ureas.