bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Fertilizer Recovery by Grain Sorghum in Monoculture and Rotation Systems
Authors: Varvel G. E. , Peterson Todd Andrews 
Published: July 2010

AbstractGrain sorghum [Sorghum bicolor (L.) Moench] has become a major dryland crop for the Great Plains, but information on production in rotations is limited. This study was conducted to determine N fertilizer recovery and use by grain sorghum in monoculture and rotational systems. Grain sorghum was grown under rainfed conditions on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic, Typic Argiudoll) in: (i) continuous grain sorghum monoculture, (ii) a 2‐yr soybean [Glycine max (L.) Merr.]‐grain sorghum rotation, (iii) a 4‐yr rotation of soybean‐corn [Zea mays L.]‐oat [Avena sativa (L.)] + clover [80% Melilotus officinalis (L.) and 20% Trifolium pratense (L.)]‐grain sorghum, and (iv) a 4‐yr rotation of oat+clover‐corn‐soybean‐grain sorghum at Mead, NE. Broadcast applications of 15N‐depleted NH4NO3 were made at 90 and 180 kg N ha−1 in 1985 and 1986 to evaluate N fertilizer recovery. Fertilizer N recovery determined by isotopic methods was significantly higher for grain sorghum in monoculture (64.9%) vs. grain sorghum in rotation (54.9%). Fertilizer N recovery estimated by the difference method ranged from 118.5% in continuous grain sorghum to 9.1% in sorghum following oat+clover. Differences in N‐recovery results by the isotope and difference methods indicated N fertilizer applied to grain sorghum in various cropping systems appeared to be entering different organic soil‐N pools. These results substantiate the importance of the mineralization‐immobilization turnover (MIT) effect in N‐isotope experiments and the necessity for careful interpretation of N‐recovery results, especially between complex cropping systems.
Critical Petiole Nitrate Levels in Potato
Authors: Westcott M. P. , Stewart V. R. , Lund R. E. 
Published: July 2010

AbstractCritical nutrient concentrations (CNC), below which a yield reduction occurs, for potato (Solanum tuberosum L.) petiole nitrate (PN) have been reported for the Pacific Northwest growing region but differences in method of determination or definition of this parameter have resulted in some discrepancies in values. The objectives of this research were to document seasonal PN levels with varying levels of applied N, to determine CNC at three growth dates [tuber initiation, TI; 21 d after TI(TI + 21); and 42 d after TI (TI + 42)], and to establish the relationship between yield responses to midseason N application and CNC. Experiments were conducted at two sites on a Typic Argiboroll and three sites on a Pachic Haploxeroll in western Montana. Treatments included six or eight N rates between 0 and 336 kg N ha−1 applied as NH4NO3 before hilling and a topdressing of 67 kg N ha−1 broadcast on subplots at TI + 21. Early season PN depended on applied N, with maximum values of 25 to 30 g NO3‐N kg−1 at TI. Values declined with seasonal progression and became increasingly dependent on fertilizer N rates. The N topdressed at TI + 21 increased PN level 6 g kg−1 at TI + 42 compared to non‐topdressed areas. Linear plateau regression of relative yield against PN revealed CNC values of 25 g kg−1 at TI 14 g kg−1 at TI + 21, and 10 g kg−1 at TI + 42. Statistical analysis, could not separate the TI + 21 and TI + 42 regressions, indicating a CNC of 13 g NO3‐N kg−1 throughout the period of tuber bulking. Yield responses to topdressed N, however, were documented only when PN values were below 11 g NO3‐N kg−1 at TI + 21. Conservative interpretation of critical nutrient concentration is justified.
Recovery of Point‐Injected Labeled Nitrogen by Corn as Affected by Timing, Rate, and Tillage
Authors: Timmons D. R. , Baker J. L. 
Published: July 2010

AbstractPoint‐injection technology is being developed to improve fertilizer management, particularly N management. This study was conducted to evaluate the effects of the rate (number) and timing of point‐injections of an ammonium nitrate (NH4NO3) solution on N uptake and corn growth and to measure any differences due to tillage. Nitrogen‐15 depleted NH4NO3 (AN) was hand‐injected beside individual plants at the V1, V5, and/or V9 growth stages at rates of 50, 100, and/or 200 kg N ha−1 with fall moldboard plow (MP), fall chisel plow (CP), and ridge‐till (RT) systems. While MP had the highest grain and total dry matter production (but with the lowest N concentrations in those materials), tillage was not a significant factor in either the percentage of the total plant N derived from labeled AN (NF) or its recovery (NR) for any stage sampled. Generally the year (i.e. different environmental conditions) and application timing or a timing‐by‐year interaction had the greatest influence on NF and NR. Although plants sampled at the V9 stage on the average recovered more N from the V1 application (39%) vs the V5 application (27%), at maturity NR values for grain (35%) and total dry matter (47%) were the same for both V1 or V5 applications (when only two applications were made). However when three applications were made (at the V1, V5, and V9 stages), NR values decreased with time of application for both grain (38, 31, and 26%, respectively) and total dry matter (53, 43, and 33%, respectively). Across application timing, grain NR values were 34 and 31%, respectively, for MP and RT. Compared with preplant knifed‐in labeled N for MP and RT systems in an adjacent simultaneous study, grain NR values for point‐injected N in this study were 16 and 6% greater, respectively, indicating that multiple injections of fertilizer N improved N‐use efficiency.
Rooting Activity and Water Use during Vegatative Development of Crested and Western Wheatgrass
Authors: Frank A. B. , Bauer A. 
Published: July 2010

AbstractCrested wheatgrass [Agropyron desertorum (Fisch. ex. Link) Schult] and western wheatgrass [Pascopyrum smithii Rybd, (Löve)] are important cool‐season forage species that have contrasting growth patterns. Knowledge of relationships among plant development stage, water use, and rooting activity would aid in understanding the responses of these species to stresses and defoliation. Our objectives were to compare evapotranspiration (ET), rooting activity, and plant water status in relation to Haun development stage of ‘Nordan’ crested wheatgrass and ‘Rodan’ western wheatgrass. These species were grown at three water treatments (50, 100, and 150% of 1 April to 31 October monthly rainfall) and two N fertilizer (11 and 110 kg N ha−1) rates in a rain‐out shelter at Mandan, ND for a 3‐yr period. The soil was a Parshall fine sandy loam (coarse‐loamy, mixed Pachic Haploborolls). Cumulative ET through early boot stage averaged 133 and 170 mm for crested and western wheatgrass, respectively. Maximum ET rate occurred at Haun stage 5 to 6 for both species. Crested wheatgrass rooting activity averaged over three water treatments increased about 4.4 cm d−1 compared to 3.7 cm d−1 for western wheatgrass. Both species exhibited rooting activity to 1.2 m by mid‐May when western wheatgrass had developed to Haun stage 4.9 and crested wheatgrass to 5.7. Water use‐efficiency of crested wheatgrass decreased as water treatment and Haun stage increased, but western wheatgrass did not change with either. Water use‐efficiency of crested wheatgrass, but not of western wheatgrass, was greater at 110 than at 11 kg fertilizer N ha−1. Information on the simultaneous development of plant aerial parts and rooting activity contributes to an understanding of the water‐use relations of these species and has application in development of growth and yield simulation models.
Seed Spacing for Nonthinned Sugarbeet Production
Authors: Eckhoff J. L. A. , Halvorson A. D. , Weiss M. J. , Bergman J .W. 
Published: July 2010

AbstractIrrigated sugarbeet growers traditionally overseed their crop to assure adequate stands, then hand thin to a final population. The extra seed and hand labor costs may possibly be eliminated. The objective of this study was to determine optimum seed spacing for the greatest sucrose production in nonthinned sugarbeet. ‘AC‐102’ sugarbeet (Beta vulgaris L.) was planted at 10–, 15, 19–, and 23–cm intrarow seed spacings for 4 yr in Sidney, MT, to determine optimum seed spacing for greatest sucrose production of nonthinned sugarbeet. The fall ridging/spring deridging system was used to assure sufficient moisture for emergence. Successful stands were established without supplemental irrigation in 1984, 1985, and 1986, but in 1987, rains after planting and before emergence caused severe crusting of the soil which reduced stands. Seedling and harvest plant densities decreased with wider seed spacing in all years. Sucrose content decreased and impurities increased as seed spacing increased. Yields varied across years, but increased sucrose content and decreased impurities of beets planted with the 10‐ and 15‐cm spacings generally resulted in highest gross sucrose and estimated recovered sucrose yields
Reseeding Potential of Crimson Clover as a Cover Crop for No‐Tillage Corn
Authors: Myers J. L. , Wagger M. G. 
Published: July 2010

AbstractLeguminous cover crops can provide biologically fixed N to a subsequent corn (Zea mays L.) crop as well as erosion control and moisture conserving mulch, but establishment is costly and often unsuccessful. A field experiment was conducted for 3 yr to determine the self‐reseeding potential of crimson clover (Trifolium incarnatum L.) and its N contribution in a no‐tillage corn production system. Four cover crop management treatments (fallow, annual‐seeded, volunteer‐reseeded, and volunteer strip‐reseeded) were combined factorially with four fertilizer‐N rates (0, 50, 100, or 150 kg ha−1) applied to the subsequent corn crop. The annual‐seeded, volunteer‐reseeded, and volunteer strip‐reseeded clover treatments were desiccated at corn planting. Averaged over 3 yr, crimson clover dry matter was 2.6, 4.2, and 3.5 Mg ha−1 for the annual‐seeded, volunteer‐reseeded, and strip‐reseeded treatments, respectively. In 1988 and 1989, cover crop treatments produced mean corn grain yields of 6.0 and 6.1 Mg ha−1 compared to fallow treatment yields of 3.4 and 4.0 Mg ha−1, respectively. This same pattern was reflected in the silage yields and total corn N uptake. Corn grain yields were unaffected by fertilizer‐N rate in two out of 3 yr due to limited rainfall. Both self‐reseeding treatments successfully reestablished each year and increased corn yields primarily by a mulching effect. Allowing crimson clover to mature before chemical desiccation or leaving strips between corn rows to produce seed appear to be effective methods of reseeding clover in a no‐tillage corn silage production system.
Germination Response of Subterranean, Berseem, and Rose Clovers to Alternating Temperatures
Authors: Evers G. W. 
Published: July 2010

AbstractAnnual clover (Trifolium spp.) stands are sometimes poor because of low and slow germination due to unfavorable temperatures. The study was conducted to identify optimum temperature for germination of relatively new clover species to the U.S. Southeast to improve stand establishment. High temperature germination was also examined to estimate summer germination which usually results in seedling mortality and a decrease of the soil seed‐bank. Seed of 10 cultivars of T. alexandrinum L., T. brachycalycinum Katzn. and Morley, T. hirtum All., T. subterraneum L., and T. yanninicum Katzn. and Morley were subjected to alternating 12 h day/12 h night temperatures of 15/5, 20/10, 25/15, 30/20 and 35/25 °C. Germination counts were made at 3, 6, 9, and 12 d to determine percent germination and germination rate index (GRI). Germination was >80% for all entries at the three lowest temperature treatments except ‘Larisa’ subclover at 25/15 °. At 30/20 °C, germination of ‘Bigbee‘ berseem and T. brachycalycinum subclovers decreased to 54 to 66%, while the other species decreased to <35%. The 35/25 °C treatment suppressed germination to <25%. The optimum temperature for GRI was 25/15 followed by 20/10, 15/5, 30/20, and 35/25 °C. The optimum germination temperature of 25/15 °C occurs in October along the Texas‐Louisiana Gulf Coast. September plantings (30/20 °C) in this area should be limited to T. alexandrinum and T. brachycalycinum species. Cultivars that germinate at summer temperatures of 35/25 °C or higher should be avoided unless they have a high hard‐seed content.
Lowland Rice Apical Development: Stages and Cultivar Differences Detected by Electron Microscopy
Authors: Senanayake N. , De Datta S.K. , Naylor R.E.L. , Thompson W.J. 
Published: July 2010

AbstractIdentification of growth stages and cultivar differences are necessary to develop efficient N fertilizer management for lowland rice (Oryza sativa L.). To help characterize growth stages an electron microscope was used to identify different panicle development stages, cultivar growth differences, and potential yield loss periods. Varieties IR50 (90‐d maturity) and IR42 (120‐d maturity) were grown at the International Rice Research Institute during the 1987 wet season. Thirteen morphologically different development stages up to floral organ development were identified. Between cultivars, duration of each development stage varied. Necknode differentiation was defined as physiological panicle initiation (PI) and observed at growth stage (GS) 1.8 occurring 35 days after seeding (DAS) in IR50 and at GS 1.10 (49 DAS) in IR42. Visual panicle initiation (VPI) was observed at GS 1.9 (42 DAS) in IR50 and at GS 1.11 (64 DAS) in IR42. Panicle development took 15 to 18 d (4–7 d for panicle branches) in IR50 and 24 to 31 d (11‐15 d for panicle branches) in IR42. Therefore the present N management practice of N topdressing 5 to 7 d before VPI coincided with PI for short duration IR50 but not for later maturing IR42. Preflowering and post flowering spikelet abortion reduced the spikelet number in IR50 and more so in IR42 where preflowering spikelet abortion started even before spikelet development was completed. Comprehensive N timing studies based on rice apical development stages are required for improving N efficiency and increasing rice yields.
Mulch Effect on Soil Properties and Tomato Growth Using Micro‐Irrigation
Authors: Tindall James A. , Beverly R. B. , Radcliffe D. E. 
Published: July 2010

AbstractAlthough use of micro‐irrigation has risen steadily in Georgia, few studies have been reported describing its effect on yield or rooting distribution of tomato (Licopersicon esculentum). The objective of this experiment was to determine the effects of mulch type (plastic mesh and straw) and micro‐irrigation on soil physical properties and growth of ‘Celebrity’ tomato. In 1986, an experiment was initiated on a Cecil sandy loam (clayey, kaolinitic, thermic, Typic Kanhapludult) at Griffin, GA. Tomato yield and root growth, soil temperature, and water potential in 1987 and 1988 were compared using black plastic mesh and straw mulches and three micro‐irrigation frequencies: control (no irrigation), daily, and twice weekly. Soil properties beneath the two types of mulches were compared in terms of surface evaporation, measured during 24‐h periods several times each year and bulk density, organic C, pH, infiltration rate, and cone index measured at the end of the 1988 growing season. Straw mulch resulted in a significantly greater infiltration rate, and lower pH, bulk density, surface evaporation, cone index, soil temperature and matric potential than the plastic mulch. Yields were higher under the straw mulch compared to the plastic mulch and irrigation increased yield with a straw mulch in 1987 but not 1988. Yields were not increased by irrigation of the plastic mulch treatment. Straw mulches have the potential to improve tomato yields in high‐temperature environments, provided soil pH is controlled.
Stomatal Responses of Field‐Grown Cotton to Radiation and Soil Moisture
Authors: Petersen K. L. , Moreshet S. , Fuchs M. 
Published: July 2010

AbstractField research conducted on stomatal responses to water stress has generally focused on sunlit leaves and ignored the role of shaded leaf conductance. This study was carried out on a cotton crop (Gossypium hirsutum, cv. Acala SJ2) to quantify and compare sunlit and shaded stomatal conductance under variable water stress conditions, and to identify the primary environmental parameters regulating the stomatal conductance of sunlit and shaded leaves. Photosynthetically active radiation (PAR), leaf temperature, humidity, and stomatal conductances for both abaxial and adaxial leaf surfaces were measured on cloudless days during two field seasons in 1988 and 1989. Average daytime shaded leaf conductance was approximately 41 and 36% that of sunlit leaves in non‐stress and severe water stress conditions, respectively. The primary environmental parameter affecting sunlit leaf conductance was PAR. Shaded leaf conductance was weakly correlated to PAR and leaf temperature, respectively, under non‐stress conditions. Under water stress, shaded and sunlit leaf conductances were not correlated to leaf temperature. Leaf conductance was not correlated to humidity under any test condition. The derivative of stomatal conductance with respect to PAR decreased as PAR increased, with most of the change occurring in the PAR range typically obtained in the shaded fraction of the canopy. Increasing moisture stress progressively decreased the stomatal response to PAR. When sunlit and shaded leaves were pooled together, a curvilinear regression improved the correlation with PAR. Abaxial conductance comprised a greater percentage of leaf conductance for shaded than for sunlit leaves.
Program for Investigating Genotype‐Environment Interaction
Authors: Lin C.S. , Butler G. , Hall I. , Nault C. 
Published: July 2010

AbstractThis program was written to investigate genotype‐environment (GE) interaction in two‐way classification data. The analysis consists of three parts: (i) stability analysis of genotypes based on a regression or an ANOVA model, (ii) estimation and plotting of residuals, and (iii) cluster analysis for dissecting the data set into homogeneous subsets. These analyses provide diagnostic information to assess genotypic response characteristics and enable a scientist to group the genotypes in such a way that the genotypes within each subset display no GE interactions. It is hoped that by dissecting the data into homogeneous subsets the interaction structure of the data can be revealed. The program can handle five methods depending on whether a regression (linear or quadratic) or an ANOVA model is used, and whether grouping is done with respect to the similarity of GE interaction alone or the genetic effect and GE interaction combined.
Nitrogen Concentration of Young Corn Plants as an Indicator of Nitrogen Availability
Authors: Binford G. D. , Blackmer A. M. , Cerrato M. E. 
Published: July 2010

AbstractSoil tests for evaluating the N status of cornfields in late spring show promise as a tool for improving N management during corn production. An alternative tool for evaluating N status is tissue testing, which offers the potential advantages of easier sampling and better integration of factors that influence N availability. Here we evaluate total N concentrations of whole corn (Zea mays L.) plants in late spring as an indicator of N availability in cornfields. Studies were conducted at 14 site‐years in Iowa during 1986, 1987, 1988, and 1989. Whole plant samples were taken when corn was 15 to 30 cm tall. Total N concentrations in these plants were determined. Relationships between concentrations of N in young plants and fertilizer N applied were not consistent across the 14 site‐years. The concentrations of N in young plants were poor predictors of soil NO3 concentrations in situations where good relationships between soil NO3 concentrations and grain yields occurred. The tissue test could not detect excessive amounts of NO3 in soils. Concentrations of N in young plants were greatly influenced by factors having relatively little effect on final yields. Overall, the results show that a tissue test based on the concentrations of N in young plants would not be a reliable indicator of the N availability in cornfields.
Morphological Development of Switchgrass and Kleingrass
Authors: Sanderson Matt A. 
Published: July 2010

AbstractAccurate and precise measurements of plant maturity are essential in research involving perennial warm‐season grasses. The objective of this study was to devise and refine such an index for use with determinate and indeterminate flowering warm‐season perennial grasses. An index of 35 separate stages distributed among three major developmental events (leaf, stem, and reproductive development) was devised and tested on switchgrass (Panicum virgatum L., determinate flowering habit) and kleingrass (Panicum coloratum L., indeterminate flowering habit). Switchgrass and kleingrass were sampled in two growth periods, spring and summer of 1989. Switchgrass only was sampled in spring of 1990. At each sampling, 30 to 50 tillers were classified into stages, counted, dried, and weighed. An additional 30 to 50 tillers were separated also into leaf, stem, sheath, and inflorescence (if exserted) fractions. Kleingrass flowered earlier and developed morphologically nearly three times faster than switchgrass in spring 1989 and twice as fast in summer 1989. In 1990 switchgrass exhibited a sigmoidal development pattern with three distinct phases, each with a different rate of development. The phases were related closely to temperature and rainfall patterns with greater rates of development occurring during relatively cool and wet periods. The experimental index described switchgrass and kleingrass development well. Most stages were rapidly and easily recognized. Reproductive stages were sometimes subjective and may have to be revised.
Model Evaluation for Perennial Grasses in the Southern United States
Authors: Overman A. R. , Wilkinson S. R. 
Published: July 2010

AbstractModels can be used to estimate yield response of grasses to applied N. This analysis was conducted to show variation of model parameters among grasses at the same location and differences among locations. The logistic equation was used to relate annual dry matter yield to applied N for four locations (Blairsville, GA; Fayetteville, AR; Thorsby, AL; Jay, FL) and five perennial grasses [bermudagrass (Cynodon dactylon L., Pers.), bahiagrass (Paspalum notatum Flugge), tall fescue (Festuca arundinacea Schreb.), dallisgrass (Paspalum dilatatum Poir.), and orchardgrass (Dactylis glomerata L.)]. The model contained three parameters (A, b, c). It was shown by analysis of variance that all grasses exhibited common exponetial coefficients (b, c) for each location, with variation among grasses and with water availability assigned to the linear coefficient (A). Applied N, N1/2, to reach one‐half maximum yield appeared to be inversely related to clay content of the soil. Maximum efficiency of conversion of applied N to dry matter at N = N1/2 was highest for Coastal bermudagrass (approximately 40). The logistic equation provides an excellent model for yield response to applied N.