bluuebunny/crossref_metadata_2025_split huggingface dataset:
Yield Component Differences between Naked and Conventional Oat
Authors: Peltonen‐Sainio Pirjo 
Published: July 2010

AbstractGrain yield of naked oat (Avena sativa var. nuda L.) is lower than that of conventional hulled cultivars. This field study was conducted to determine yield component differences between naked and conventional oat and to assess the potential of naked oat as a grain crop for northern environments. Studies were conducted at the Viikki Experimental Farm, University of Helsinki, Finland, in 1991 and 1992. Grain yield and 24 morphophysiological traits of 10 naked and 6 hulled lines were compared. Grain yield was 30% lower in the naked lines than in the hulled ones. Due to the high hull content ( ≈ 25%) of conventional lines, they produced only 10% higher groat yields than the naked oat lines. Naked lines had fewer panicles per square meter, due to their lower emergence, suggesting that a 10% increase in planting density of naked lines may result in equal groat yields of naked and conventional lines. Compared with hulled lines, naked lines had higher vegetative phytomass associated with lower harvest index. When grains were dehulled, the harvest index of naked lines did not differ significantly from that of conventional lines. The naked oat lines were characterized by fewer spikelets per panicle and more grains per spikelet compared with hulled lines. To achieve high grain yield and increase the competitive ability of naked oat, improvement in partitioning photosynthetic assimilates into grain is needed.
Plant Nitrogen Status and Boll Load of Cotton
Authors: Gerik T. J. , Jackson B. S. , Stockle C. O. , Rosenthal W. D. 
Published: July 2010

AbstractNitrogen management is important in determining cotton (Gossypium hirsutum L.) yield and fiber quality. Plant tissue tests are often used to estimate cotton N status and determine if further fertilization is needed during the growing season. This study was conducted to examine the relationship between plant tissue tests of petiole NO3 concentration and leaf N content and cotton performance as measured by vegetative growth (i.e., leaf area) and boll load. Nitrogen rates of 0, 18, 36, 72, and 144 mMN pot−1 were applied at 2‐wk intervals beginning 13 and 26 d after emergence in 1987 and 1988 through boll maturity to a greenhousegrown cultivar, Stoneville 213. The strong relationship between leaf N and leaf area and boll number (r2 = 0.80 and r2 = 0.89) 1 wk after first flower appearance suggests that the transition period between vegetative and boll development is a critical time to assess cotton's N status in relation to yield. Nitrogen deficits had little effect on boll weight, boll period duration, and number of main stem nodes. Although boll weight decreased with increasing N deficit, final boll weight of the high‐N plants were within 20% of the plants receiving low N supply. The relationship between leaf N and petiole NO3 content, was best described by Y = a + bXC; however, with this function only one‐half of the variation in leaf N was accounted for by variation in petiole NO3 content (r2 = 0.48). Leaf area and boll number were poorly correlated with petiole NO3 content. Leaf N content was a better predictor of cotton vegetative growth (as indicated by LAI) and boll number than petiole NO3 content, particularly when measurements are made 1 wk after first flower.
Alfalfa Yield and Quality Are Affected by Soil Hydrologic Conditions
Authors: Buscaglia H. J. , van Es H. M. , Geohring L. D. , Vermeulen H. C. A. M. , Fick G. W. , Lucey R. F. 
Published: July 2010

AbstractSoil water management practices may affect crop growth by reducing periods of excess or shortage of soil water. The objective of this study was to evaluate forage yield and quality as affected by soil hydrologic conditions imposed by four water management practices. The experiment was conducted on a Muskellunge sandy clay loam soil (fine, mixed, frigid Aeric Ochraqualf) in northern New York during three growing seasons (1989–1991), each involving three cuttings of an alfalfa (Medicago sativa L.)—timothy (Phleum pratense L.) intercrop. Treatments consisted of (i) drain open at all times (OD); (ii) drain closed at all times (CD); (iii) drain open in winter, closed in summer (SC); and (iv) drain open in winter and the water table at a target 0.6‐m depth using a weir and supplemental irrigation in the summer (SW). Lack of drainage under CD resulted in longer periods of soil saturation and reduced yields by 9 and 16% compared with OD in the first and second growth cycle of 1990 and by 17% during the first growth cycle of 1991. Increased soil wetness after drain closure under SC did not result in yield increases compared with conventional drainage during dry periods and caused a small decrease during a wet growth cycle. Maintaining a water table at 0.6‐m depth resulted in 30% yield increase in the dry year 1991, but none in 1989 and 1990. Soil temperatures were not affected by water management. When yields were reduced, crude protein and elemental (P, Ca, K, Mg) concentrations were generally higher, and fiber and lignin levels were generally lower, indicating that increased forage quality partially compensates for lower yields, especially under excess water conditions.
An Extended Model of Forage Grass Response to Applied Nitrogen
Authors: Overman A. R. , Wilkinson S. R. , Wilson D. M. 
Published: July 2010

AbstractA simple model is needed that relates forage grass production (yield and N removal) to management factors (applied N, harvest interval, and water availability). The objective of this analysis was to extend a previous model to include quantitative coupling between yield and N removal in response to applied N for perennial grasses. The extended model was developed from three postulates: (1) annual dry matter yield follows logistic response to applied N, (2) annual plant N removal follows logistic response to applied N, and (3) the N response coefficients are the same for both. Three additional consequences derive from these postulates: (i) plant N concentration response to applied N follows a ratio of logistic functions, (ii) annual dry matter yield and plant N removal are related by a hyperbolic equation, and (iii) plant N concentration and plant N removal follow a linear relationship. Data from a field study in Louisiana with dallisgrass [Paspalum dilatation Poir.] grown on Olivier silt loam (fine‐silty, mixed, thermic Aquic Fragiudalf) were used to demonstrate applicability of the model and to illustrate procedures. Analysis of variance supported Postulate 3 for these data, with an overall correlation coefficient of 0.9990. Plant N concentration (Nc for this study was bounded by 11.8 <Nc< 27.5 g kg−1. Maximum yield for the study reached 57% of potential yield at plant N removal of 427 kg ha−1. Potential yield of 27.5 Mg ha−1 appears to be in the range of values reported in the literature. Further use of this model should provide added insight into the coupling among various mechanisms that control forage production.
Responses of Kura Clover to Sheep Grazing and Clipping: II. Below‐Ground Morphology, Persistence, and Total Nonstructural Carbohydrates
Authors: Peterson Paul. R. , Sheaffer Craig C. , Jordan Robert M. , Christians Charles J. 
Published: July 2010

AbstractBelow‐ground morphology and total nonstructural carbohydrate (TNC) reserve patterns may explain the excellent persistence of kura clover (Trifolium ambiguum M. Bieb.). Our objective was to determine the effects of frequent clipping and sheep (Ovis spp.) grazing on the below‐ground morphology, TNC reserves, and persistence of kura clover. Clipping and sheep grazing experiments were initiated on a 5‐yr‐old stand of ‘Rhizo’ kura clover on a Waukegan silt loam (fine‐silty over sandy, mixed, mesic Typic Hapludoll) and conducted for 3 yr. Crowns, rhizomes, and roots comprised about 25, 45, and 30%, respectively, of the total below‐ground mass sampled to a 15‐cm depth, which averaged 6600 kg ha−1. Primary crowns decreased from 95 to 55 m−2 during 2 yr of grazing, whereas secondary crowns produced by rhizomes averaged 1340 m −2 and dominated aerial shoot production. Crown, rhizome, and root TNC concentrations ranged from 87 to 212, 85 to 248, and 114 to 239 g kg −1 DM, respectively, and followed a common pattern of TNC being lowest in June and increasing linearly to a maximum in the fall. Clipping treatments ranging from three to six cuttings per year had little impact on below‐ground morphology and TNC concentrations, probably because of residual leaf area remaining after clipping. Persistence was excellent under all defoliation treatments. We conclude that established kura clover has an extensive crown‐rhizome‐root system which confers the ability to maintain adequate TNC concentrations for persistence under a range of potential defoliation regimes.
Dinitrogen Fixation and Nitrogen Transfer in Birdsfoot Trefoil–Orchardgrass Communities
Authors: Farnham Dale E. , George J. Ronald 
Published: July 2010

AbstractBirdsfoot trefoil (Lotus comiculatus L.) is an important perennial forage legume used primarily for pasture. Despite its traditional usage as a source of nitrogen for cropping systems, little information is available on the amounts of atmospheric dinitrogen (N2) that birdsfoot trefoil fixes or transfers to an associated grass during long‐term stands. Field research was undertaken to compare N2 fixation and N transfer potentials of three birdsfoot trefoil cultivars and one experimental line (hereafter referred to collectively as the birdsfoot trefoil cultivars). These were seeded in binary mixtures with orchardgrass (Dactylis glomerata L.). Dinitrogen fixation and N transfer were estimated by 15N isotope dilution, using orchardgrass pure stands as a reference. Over the 2‐yr study, percentage legume N derived from fixation ranged from 93 to 95% among the birdsfoot trefoil cultivars. Dinitrogen fixation usually did not differ among cultivars within harvests. Total‐season fixed‐N yields among cultivars for the two years ranged from 90 to 138 kg ha−1. Percentage orchardgrass N derived from N2 fixation and N transfer ranged from 8 to 46%. Nitrogen transfer did not differ among birdsfoot trefoil cultivars at any harvest. Total‐season transferred‐N yields ranged from 4 to 42 kg ha−1, with no differences among cultivars. Under the conditions of this study, the birdsfoot trefoil cultivars tested generally did not differ in their abilities to fix atmospheric N2 or to transfer fixed N to associated orchardgrass.
High Pressure Water Injection and Core Cultivation of a Compacted Putting Green
Authors: Murphy James A. , Rieke P. E. 
Published: July 2010

AbstractTraditional core cultivation practices are typically performed in spring and/or fall to alleviate problems associated with soil compaction on golf course putting greens. Equipment was commercially developed that provides short‐time pulse injection of highly pressurized water that could relieve soil compaction stress while limiting playing surface disturbance. This study evaluated the response of ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.) growing on a modified loamy sand (originally a fineloamy, mixed, mesic, Typic Hapludalf) to hollow tine cultivation (HTC) and high pressure water injection cultivation (WIC). Cultivation treatments were applied three and two times in 1988 and 1989, respectively, on an experimental putting green receiving periodic compaction from rollers (50 kPa). Water injection was equal or superior to hollow tine cultivation in reducing soil bulk density, and increasing porosity and saturated hydraulic conductivity in the 0‐ to 76‐mm depth zone. Hollow tine cultivation reduced soil strength by 1.33 MPa at the 30‐mm depth compared with no cultivation, but only water injection cultivation provided a significant reduction in soil strength of the 70‐ to 100‐mm depth zone. Both methods increased bentgrass shoot growth rate after treatment compared with no cultivation. Hollow tine cultivation reduced surface (0 to 100 mm) root weight density by 26%, as well as root numbers observed along minirhizotrons, compared with the check and WIC plots. Root and crown damage and root removal during HTC was the likely cause for this response. Water injection cultivation offers the potential for routine cultivation during periods of high site usage and environmental stresses with either no effect or an improvement in visual quality.
Soil Sampling with a Modified Chainsaw
Authors: Ashworth John , Crépin J. M. , Repski Rip 
Published: July 2010

AbstractIn uncultivated fields containing residual banded fertilizer, wide variability in analytical results for individual soil samples can make it extremely time‐consuming to obtain a representative composite for analysis. This study was done to test whether individual soil samples, taken from a series of slots cut across bands of residual fertilizer, would show less analytical variability than samples taken at a series of random points. A chainsaw fitted with a catcher was used to collect soil from slots cut across stubble rows, and an auger used to take point samples, on field plots with residual N, P, K, and S fertilizer banded ≈ 6 cm deep at 18‐cm spacing. Plots at eight sites on Typic Cryoborolls, mostly clay loam in texture, were sampled after harvest. The samples were analyzed for extractable N, P, K, and S. Out of 32 comparisons, coefficients of variation (CV) in analytical results were lower in 28 instances when samples were taken by chainsaw rather than by auger. Judging from CV values, a composite sample made up of soil from ≈ 15 slots would in most cases have given an accurate estimate of residual amounts of all four crop nutrients at the eight sites. With an auger, from 40 to 50 sampling points would have been required for comparable accuracy. The results suggest that, when sampling uncultivated soil containing residual banded fertilizer, a valid composite sample could be obtained more conveniently by slot‐cutting than by sampling at points.
Rhizotrons: Their Development and Use in Agricultural Research
Authors: Klepper Betty , Kaspar Thomas C. 
Published: July 2010

AbstractRhizotrons are tools for making nondestructive, repeated observations and measurements of root systems. Primary objectives of this review are to report features of several rhizotrons and to describe the types of research that have been and will be performed in them. Rhizotrons are permanent installations, generally with transparent viewing surfaces for measurement of plant roots. Typically, these facilities have control of drainage and are well instrumented for macroscopic and microscopic observations of roots. They are excellent for getting descriptive and semiquantitative data on simultaneous changes in root and shoot systems of different cultivars or species over seasons or in response to treatments. Rhizotrons can also be designed to allow measurement of mass balances of water and nutrients within the rooting volume of a crop. Future uses of rhizotrons will include research on the root‐zone behavior of soil nutrients such as NO3, detailed measurement of processes such as diffusion and mass flow of liquids and gases in soils, and development of better information on the role of soil biota in nutrient cycling and uptake. This new information will permit better definition of the role of root systems in plant growth and development.
Integration of Weed Management and Tillage Practices in Spring Dry Pea Production
Authors: Young F. L. , Ogg A. G. , Boerboom C. M. , Alldredge J. R. , Papendick R. I. 
Published: July 2010

AbstractInformation about long‐term efficient production systems is needed to assist growers in adopting conservation cropping practices for spring dry pea (Pisum sativum L.), a biologically important pulse crop grown in the Pacific Northwest and Canada. From 1985 to 1991, an integrated pest management field study examined the influence of three weed management levels and two tillage regimes on the productivity of spring pea grown in a winter wheat (Triticum aestivum L.)‐spring barley (Hordeum vulgare L.)‐spring pea rotation. When averaged over 6 yr, spring pea yielded the least with the minimum weed management level in either the conservation (chisel plow) or conventional (moldboard plow) tillage system. In conservation tillage, yields were similar at the moderate and maximum weed management levels and up to 335 kg ha−1 more than pea with the minimum weed management level. In contrast, in conventional tillage, yields were increased only at the maximum level of control compared with the minimum level. Yields of pea grown under conservation tillage were equal to or greater than yields in conventional tillage when averaged over weed management levels. The reduced tillage system on the integrated pest management project met conservation compliance for both planting pea into spring barley residue and planting winter wheat into pea residue. In addition to reducing erosion, the conservation pea production system did not increase substantially herbicide use and cost, thus maintaining environmental quality.
Nitrogen Use Efficiency of Split Nitrogen Applications in Soft White Winter Wheat
Authors: Sowers Karen E. , Pan William L. , Miller Baird C. , Smith Jeffrey L. 
Published: July 2010

AbstractNitrogen use efficiency (grain weight per unit of N supplied from soil or fertilizer) can be reduced by overfertilization, suboptimal yields, and N losses. Nitrogen is typically fall‐applied in eastern Washington for soft white winter wheat (Triticum aestivum L.) production, and is therefore subject to overwinter losses or accumulation in deep soil layers. Increasing grain protein levels of soft white winter wheat have been attributed in part to excessive N application rates and high residual N levels. Spring N applications were evaluated over four site‐years as an option to all‐fall applied N for reducing N inputs and improving N use efficiency, thereby allowing producers to maintain productivity while controlling grain protein. Five to six N rates ranging from 0 to 140 kg ha−1 for the all‐fall N applications were compared with fall‐spring split applications of 84 to 140 kg total N ha−1. Nitrogen was applied in the spring by topdressing (TD) or with a spoke‐wheel point‐injection (PI) system. A 15N experiment was conducted at two locations during the second year to quantify N uptake from fertilizer and soil N. High preplant residual N conditions resulted in limited responses to added N. Nitrogen use efficiency was 26 to 44% lower in the 140 kg ha−1 fall‐applied N treatments than in the zero‐N control. Reduced N use was related to N losses from the system and to decreased N utilization efficiency (grain weight produced per unit plant N). Spring‐applied N, with point injection or topdressing, maintained or increased N use efficiency compared with equivalent all‐fall N rates of 84 and 112 kg N ha−1. More 15N‐labeled fertilizer (7–16% more) was recovered with a split N application than with fall‐applied N at the same total rate of 112 kg N ha−1. At maturity, 68% of plant N was from soil sources with a split application, compared with 80% with an all‐fall application. These results suggest spring‐N applications with point injection or topdressing can improve fertilizer N recovery and N use efficiency over preplant applications in dryland winter wheat.
Growth of Soybean Stressed by Nematodes, Herbicides, and Simulated Insect Defoliation
Authors: Browde Joseph A. , Pedigo Larry P. , Owen Michael D. K. , Tylka Gregory L. , Levene Brian C. 
Published: July 2010

AbstractSoybean [Glycine max (L.) Merr.] responses to combinations of stress factors generally are unknown. Research was conducted in 1989, 1990, and 1991 to quantify growth responses to stresses from soybean cyst nematode (SCN; Heterodera glycines Ichinohe), acifluorfen {5‐[2‐chloro‐4‐(trifluoromethyl)phenoxy]‐2‐nitrobenzoic acid} plus bentazon [3‐(1‐methylethyl)‐(1H)‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide] herbicides, and simulated green cloverworm [GCW; Plathypena scabra (F.)] defoliation. Treatments were combinations of at‐planting SCN soil density, acifluorfen plus bentazon rate, and simulated GCW defoliation level. Herbicides were applied at V6 soybean development, and GCW feeding was simulated from R2 to R4 soybean development. Plant growth was quantified at V4, R2, and R4 developmental stages. Herbicide stress was assessed by leaf stomatal conductance and visible foliar injury. Herbicides reduced conductance and caused visible injury each year, and limited growth (plant height, leaf area, pod number, and dry weight of leaf, pod, and stem plus petiole) in 1990 and 1991. Likewise, defoliation reduced leaf area each year, but reduced growth (plant height and leaf dry weight) in 1990 and 1991 only. Uncontrolled environmental factors probably confounded growth responses in 1989. Although no herbicide × defoliation effects on growth were found, defoliation caused greater reductions in canopy quantity and quality for herbicide‐injured plants in 1990 and 1991. Targeted stress from SCN was achieved in 1990, and interaction with herbicides decreased conductance, increased visible herbicide injury, and reduced leaf area, plant height, pod number, and pod dry weight. These data support the potential for stresses from SCN and acifluorfen plus bentazon to cause more‐than‐additive reductions in soybean growth.
Fall Management Effects on ‘Grasslands Matua’ Prairie Grass Production and Sward Characteristics
Authors: Jung Gerald A. , Shaffer John A. , Everhart John R. 
Published: July 2010

AbstractRuminant animal production costs in the northeastern USA can be lowered by extending the fall grazing season. Two field experiments were initiated with prairie grass [Bromus unioloides (Willd.) H.B.K. cv. Grasslands Matua; syn. B. willdenowii Kunth] to determine effects of fall management (i.e., clipping) on forage production and winter survival. Plantings were made in May 1986 for Exp. 1 and June 1990 for Exp. 2. Experiment 1 addressed date of fall harvest and residual stubble height effects on fall yields and tiller density, winter survival, and spring yields and tiller density. Experiment 2 addressed the interaction of harvest frequency and residual stubble height on the same parameters as for Exp. 1. Fall yields of Matua peaked at 4.0 Mg ha−1 in late October to early November (Exp. 1 and 2). Mean fall yields were reduced 20, 40, and 60% as residual stubble height was increased from 7.5 cm to 12.5, 20.0, or 25.0 cm, respectively (Exp. 1). Spring yields were high from plots clipped to a 7.5‐cm stubble in September and decreased as fall harvest was delayed to November (Exp. 1). Spring yields from plots clipped to a 7.5‐cm stubble in late November were only 20 to 25% of yields from plots clipped in September. Leaving a higher residual stubble in fall compensated considerably for the deleterious effect of harvesting in late fall. Clipping to a 20.0‐, 12.5‐ or 7.5‐cm stubble in fall resulted in linear decreases in spring yields as fall harvest was delayed from September to November, and clipping to 25.0 cm gave a quadratic response, with a peak at mid‐October. Matua plots that were harvested once in late fall or not at all (check) recovered very slowly in spring and had a lower yield potential than plots that had been harvested two, three, or four times in fall. To optimize production of Matua in fall and spring it is recommended that one summer rest period be extended to allow natural reseeding and that two or three fall harvests or grazings be taken to increase stand density and winter survival.