bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduced Phosphorus Application on Bahiagrass and Water Quality
Authors: Rechcigl J. E. , Payne G. G. , Bottcher A. B. , Porter P. S. 
Published: July 2010

AbstractPhosphorus is considered to be the major factor causing eutrophication of Lake Okeechobee and other waterways in Florida. An important source of P for Lake Okeechobee is runoff of soluble P fertilizer applied to bahiagrass (Paspalum notatum Flugge) pastures. A study was conducted to ascertain whether P application levels could be reduced below current agronomic recommendations without affecting pasture yields or quality and to determine the effects of P application on surface water quality. A field study was conducted on a bahiagrass pasture to assess the yield response of bahiagrass to five annual rates of P (0, 6, 12, 24, and 48 kg ha−1) and two application times (dry season and wet season). Fertilizer treatments were arranged in a randomized complete block design with four replications on an Immokalee fine sand (sandy, siliceous, hyperthermic Arenic Haplaquods). Results indicate that P fertilization rates could be reduced from 48 to 24 kg P ha−1 without affecting yields or quality of bahiagrass. Yields in 1989 averaged 11.4, 14,7, and 10.4 Mg ha−1 for the 48, 24, and 0 kg P ha−1 treatments, respectively. Time of P application had no effect on yields or quality of bahiagrass. There was a linear increase in Mehlich I extractable P in the A and E horizons and a quadratic increase to P in the Bh horizon in 1989. Extractable P ranged from 3.8 to 22.5, 1.3 to 2.5, and 21 to 55 mg P kg−1 for the A, E, and Bh horizons, respectively. Phosphorus concentrations in surface water runoff was reduced from 33 to 60% as P application rates were decreased from 48 to 12 kg P ha−1 while total P loss was reduced from 17 to 78%, respectively. Recommended reductions in P application should result in substantial cost savings to producers and also reduce P inputs into surface water.
Seed Yield and Water‐Use Efficiency of White Lupin as Influenced by Irrigation, Row Spacing, and Weeds
Authors: Putnam D. H. , Wright J. , Field L. A. , Ayisi K. K. 
Published: July 2010

AbstractWhen grown on sandy soil, spring‐seeded sweet white lupin (Lupinus albus L.) is usually subject to moisture stress. Late‐germinating broadleaf weeds also compete with the crop and reduce yields. The objectives of this study were to determine the effects of five irrigation levels, two row spacings (15 and 76 cm), and late‐germinating weeds on lupin seed yield, seed protein content, and water‐use efficiency. The cultivar Ultra was grown on a loamy sand (Udotrantic Haploborolls) and irrigated with a line‐source sprinkler system. Full irrigation increased seed yield an average of 553% over non‐irrigated controls in 1988, 229% in 1989, and 52% in 1990, but seed protein concentration was reduced 2.5 to 7.9 percentage points. Applied water‐use efficiency and crude protein applied water‐use efficiency were maximized at 300 to 400 mm or less of total effective water depending upon year. Irrigation increased lupin seed yield primarily by increasing numbers of fertile branches and mainstem pods. Irrigation also increased number of seeds per pod and seed weight. Lack of late season weed control reduced yields by an average of 17% in 1988 and 1989, and 28% in 1990. Yields from narrow rows were 23 to 50% higher than those from wide rows. Generally, weed count was reduced in narrow rows. Substantial benefits of irrigation to white lupin productivity were observed on these soils, but it is unlikely that applications of more than 350 to 400 mm of irrigation water plus rainfall would increase seed yield or water‐use efficiency for spring‐sown white lupin.
Temporal Importance of Greater Light Interception to Increased Yield in Narrow‐Row Soybean
Authors: Board J. E. , Kamal M. , Harville B. G. 
Published: July 2010

AbstractIncreased light interception is considered the main factor explaining greater yield in narrow‐ compared to wide‐row spacing in soybean [Glycine max (L.) Merr.]. Controversy exists, as to when during the growth cycle the greater light interception of the narrow rows has an enhancing effect on yield. The objectives of this study were to analyze crop growth rate and yield components to determine the importance of greater light interception during vegetative (E‐R1), early reproductive (R1‐R5), and late reproductive (R5‐R7) periods to increased yield in narrow‐row culture. Field studies were conducted during 1989 and 1990 at a late (July) planting date with ‘Centennial’ soybean (determinate, Maturity Group VI) at row spacings of 100, 75, 50, and 25 cm. The test was conducted at Baton Rouge, LA on a Mhoon silty clay soil (fine‐silty, mixed, nonacid, thermic, Typic Fluvaquents). Yield increased with greater light interception as row spacing was reduced from 100 to 75 and 50 cm. Although greater light interception occurred throughout the growing season in narrow compared to wide rows, increased crop growth rate occurred only during vegetative and early reproductive periods. The main factors responsible for increased yield in narrow rows were greater fertile node production and increased pod per fertile node. These yield components are primarily determined during the vegetative and early reproductive periods. In conclusion, analyses of crop growth rate and yield components revealed that greater light interception during the vegetative and early reproductive periods was responsible for increased yield in narrow‐row culture.
Seed Yield of Bahiagrass in Response to Sward Management by Phenology
Authors: Adjei M. B. , Mislevy P. , Chason W. 
Published: July 2010

AbstractAlthough seed yield of bahiagrass (Paspalum notatum Fluegge) can be increased by burning and N fertilization, there is a need to establish the optimum stage of plant development for the application of such practices. A ‘Pensacola’ bahiagrass pasture, grown on Pomona fine sand (sandy, siliceous, hyperthermic, Ultic Haplaquods), was either burned or mowed at five stages of plant development: dormant, early vegetative, first‐raceme‐visible, and 2 or 4 wk after first‐raceme‐visible. After residue removal, plots were fertilized with 0, 50, or 108 kg ha−1 N. Seed yield, number of inflorescences, seed weight, and seed quality (1987 only) were determined in 1987 and 1988. Stage of plant development at time of residue removal affected all traits (P ≤ 0.05). Seed yield, seed weight, and seed quality were highest when residue was removed at the dormant or early‐vegetative stages of plant development. Seed dormancy, however, decreased as stage of plant development increased. Method of residue removal (burn vs mow) did not significantly (P ≤ 0.05) affect any trait except number of inflorescences in 1987, when more inflorescences were produced following mowing than burning. Nitrogen fertilization significantly (P ≤ 0.05) increased seed yield and number of inflorescences, but had no affect on seed weight or seed quality. Residue removal by burning or mowing prior to the first‐raceme‐visible stage of plant development, followed by application of 50 kg ha−1 N, produced high yields of quality bahiagrass seed.
Fertilizer‐Nitrogen Use Efficiency of Irrigated Wheat: II. Partitioning Efficiency of Preplant versus Late‐Season Application
Authors: Wuest S. B. , Cassman K. G. 
Published: July 2010

AbstractPartitioning of N to grain is an important determinant of N‐use efficiency in wheat (Triticum aestivum L.). This study evaluated the effects of N‐fertilizer treatments on N partitioning, and compared the partitioning of labeled N applied at planting with labeled N applied at anthesis. A 2‐yr field experiment was conducted with applications of 120, 180, or 240 kg N ha−1 at planting and 0, 30, or 60 kg N ha−1 at anthesis. The mean N harvest index (NHI) of N acquired from fertilizer applied at planting was 0.70, compared to 0.89 for that N acquired from fertilizer applied at anthesis. Mean NHI of total plant N derived from all sources (fertilizer and soil) was 0.74. The amount of N applied at anthesis had little effect on N partitioning, but increasing rates of preplant N from 120 to 240 kg N ha−1 caused a decrease in NHI averaging 0.10 the first yr and 0.04 the second yr. A second 2‐yr experiment, using similar N treatments and a small dose (<1 kg ha−1) of NH4−15N injected into the soil at anthesis verified these results. In the second experiment the effects of preplant N on NHI differed between cultivars; Yecora Rojo was considerably more efficient than Anza at high preplant N rates. Fertilizer N applied at anthesis was found in leaf, stem, and spike tissue 14 days after anthesis and contributed 4.2 to 16.8% of the N in each tissue at that time. Anthesis N fertilizer was also well distributed among structural, soluble, and ribulose‐1,5‐diphosphate carboxylase N feactions of flag leaves. This study demonstrated that the early season N environment has a large influence on N partitioning at maturity, whereas N applied at anthesis has little effect on N partitioning and is allocated more efficiently to grain.
Season Length and Cultivar Determine the Optimum Evapotranspiration Deficit in Cotton
Authors: Orgaz F. , Mateos L. , Fereres E. 
Published: July 2010

AbstractIn areas where the growing‐season length limits cotton (Gossypium hirsutum L.) production, irrigation practices that meet the maximum evapotranspiration (ET) demand have been shown to promote excessive vegetative growth and to reduce yield. Past experiments using limited irrigation in cotton do not provide generalized information on the magnitude of ET deficits that optimize lint yields, however. A study was conducted to determine how season length and cultivar maturity affected the response functions to ET deficits in cotton. Four cultivars (Acala SJ‐C1, GC‐510, Coker‐310, and Jaen) were studied at Cordoba (southwestern Spain) on a Typic Xerofluvent soil under variable irrigation. In 1985 and 1986, ET levels ranging from 40 to 100% of maximum ET (ETmax) were generated with a sprinkler line source. In all cultivars, biomass production and number of bolls set decreased as ET decreased, but earliness was hastened by ET deficits. The water production function of Jaen was linear; seed yield was 5300 kg ha− at ETmax (820 mm). In contrast, the production function of the three other cultivars was linear up to 85% of ETmax, but levelled off as ET approached ETmax (830 mm) because a fraction of the bolls set did not open by harvest at high ET levels. Sequential harvests up to the final date showed that, for a given genotype, the ET deficit giving maximum yield decreases as length of season increases. Thus, it is possible to define an optimum ET deficit for cotton based on cultivar earliness, growing‐season length, and availability of irrigation water.
Pressurized‐Wall Minirhizotron for Field Observation of Root Growth Dynamics
Authors: Merrill Stephen D. 
Published: July 2010

AbstractData derived from minirhizotrons, tubes installed in the field for observation of root growth, can suffer from particular conditions at the interface between tube and soil. These include the interface being excessively tight–leading to under observation of roots–or to gaps between wall and soil–leading to visibility problems and over‐proliferation of roots at the wall. Details are presented for a minirhizotron designed to overcome these problems by use of flexible and constantly pressurized outer walls. The 0.5‐mm thick, clear polyvinyl outer wall is concentric with and sealed to an inner wall of extruded acrylic. Air pressure of 10 to 20 kPa is maintained between inner and outer walls. The system appears to have yielded data of a comparable or better quality than other described rhizotron‐type devices and is recommended for usage by workers with soils that present problems to minirhizotron usage.
Productivity and Persistence of Rhizoma Peanut Pastures under Different Grazing Managements
Authors: Ortega‐S. J. A. , Sollenberger L. E. , Quesenberry K. H. , Jones C. S. , Cornell J. A. 
Published: July 2010

Abstract‘Florigraze’ rhizoma peanut (Arachis glabrata Benth.) is a perennial legume of high forage quality adapted to warm climates, but there has been no comprehensive evaluation of its responses to grazing management. In 1988 and 1989, the effects of grazing frequency and intensity on Florigraze persistence and herbage accumulation (HA) were evaluated on a loamy, siliceous, hyperthermic Grossarenic Paleudults soil. All 12 combinations of three levels of residual dry matter after grazing (RDM, 500, 1500, and 2500 kg ha‐') and four grazing cycle lengths (GC; 7, 21, 42, and 63 d between grazings, including a 0.5‐ to 2‐d grazing period) were replicated twice. Data were analyzed by fitting multiple regression equations starting with a second order polynomial model. In 1988, rhizoma peanut HA ranged from 6130 to 10 240 kg ha− and increased linearly as GC and RDM increased. There was a GC‐by‐RDM interaction for rhizoma peanut HA in 1989, whereby at low RDM, increasing GC increased HA, but GC had less effect as RDM increased. In 1989, rhizoma peanut HA of at least 8800 kg ha− was estimated to occur with GC of 42 d or longer when RDM was 1500 kg ha− or greater. Rhizoma peanut percentage in HA was greatest with high RDM and long GC, but values of 80% or greater in the second year were estimated for RDM as low as 1300 kg ha− when GC was 63 d, or with GC as low as 7 d when RDM was above 2300 kg ha−. Lowest values were obtained with low RDM and short GC. These data indicate that unlike most tropical legumes, rhizoma peanut is productive and persistent over a relatively wide range of grazing management practices.
Irrigation Method and Water Quality Effects on Corn Yield in the Mid‐Atlantic Coastal Plain
Authors: Adamsen F. J. 
Published: July 2010

AbstractDeep well sodic sources of irrigation water are often more readily available than high quality shallow or surface sources for corn (Zea mays L.) grown in the U.S. Southeast. The objective of this study was to determine the effect of irrigation water quality and irrigation method on corn production in the Virginia‐North Carolina coastal plain. Pioneer 3320 corn was grown in rotation with peanut (Arachis hypogaea L.) on a Kenansville loamy sand (loamy, siliceous, thermic Arenic Hapludult) in Suffolk, VA, in 1984, 1985, 1986, and 1988. Corn was irrigated with either overhead sprinklers or trickle lines buried 0.35 to 0.41 m below each row with sodic deep well (142 m) and non‐sodic shallow (10 m) water. Sodic water had 220 mg Na L−1, a pH of 8.5, and a sodium adsorption ratio (SAR) of 103. Non‐sodic water had 4.8 mg Na L−1, a pH of 4.8, and an SAR of 3.1. Corn yields averaged 9970 kg ha−1 with irrigation and 7650 kg ha−1 without. Irrigation method and water quality did not affect yields of irrigated corn. Soil pH increased during the study but appeared to stabilize between 6 and 7 in the surface soil. No evidence of an increase in subsoil acidity was detected. Winter rainfall and gypsum applied to the rotational peanut crop appear to be adequate to prevent the soil exchange from being dominated by Na. The results indicate that sodic water can be used to irrigate corn in the mid‐Atlantic coastal plain and that trickle irrigation can reduce water input for corn by 30% or more.
Bradyrhizobium Inoculation and Nitrogen Fertilizer Effects on Seed Yield and Protein of White Lupin
Authors: Ayisi K. K. , Putnam D. H. , Vance C. P. , Graham P. H. 
Published: July 2010

AbstractVariation in seed yield and protein levels of sweet white lupin (Lupinus albus L. cv. Ultra) in the North Central USA has limited production of the crop in this region. Poor N nutrition from biological or exogenous sources may be one of the causes of this variation. Studies were conducted under irrigation in 1988, 1989, and 1990 at Becker, MN, on a Hubbard loamy sand (sandy mixed udorthentic haploborolls) to examine the impact of Bradyrhizobium inoculation and N fertilizer on lupin seed yield, protein concentration, and yield components. Bradyrhizobium sp. (Lupinus) strains (WU425 and 96B15) were compared separately with non‐inoculated lupin controls in 1988 and then in combination in a 1:1 cell ratio in 1989 and 1990 at four concentrations of N fertilizer (0, 56, 112, 168 kg N ha−1). There were no significant differences in seed yield or protein between the two strains in 1988 but there was a trend for higher yield with WU425. Seed yield of inoculated plots was increased by an average of 51% in 1988 and two to five fold in 1989 and 1990, respectively, compared with noninoculated controls. Yield increases were due to changes in pod number or seed weight, depending upon the year of evaluation. Inoculation resulted in seed protein increases 28 to 45% greater than non‐inoculated controls at zero N. Symbiotic N2‐fixation by the difference method contributed 63 to 85% of seed N but these amounts decreased with addition of N fertilizer. Nitrogen fertilizer did not significantly increase seed yield, protein content, or protein yield of inoculated plants and seed yield of inoculated plants at zero N was always greater than that of well fertilized non‐inoculated plants. These results indicate the importance of Bradyrhizobium symbiosis in white lupin for both maximum seed yield and seed protein. Addition of N fertilizer to effectively nodulated lupin offered no advantage for either seed yield or protein.
Optimal Concentrations of Nitrate in Cornstalks at Maturity
Authors: Binford G. D. , Blackmer A. M. , Meese B. G. 
Published: July 2010

AbstractThe concentration of NO−3 in the lower portion of cornstalks at physiological maturity has been proposed as the basis for evaluating the N status of corn (Zea mays L.). Here we refine estimates of the optimal range in NO−3 concentrations for this test by using relevant economic scenarios that include 900 plot‐years of new data as well as 450 plot‐years reported earlier. The results showed that rainfall had little effect on concentrations of NO−3 identified as being optimal. However, calculations showed that optimal concentrations of NO−3 in stalks were influenced by prices of corn and fertilizer. For prices that have prevailed in the Corn Belt during the past decade, an optimal range of 0.7 to 2.0 g NO−3‐N kg−1 was shown to be more appropriate than the range originally reported. When this optimal range is used, the tissue test can be used to identify deficiencies of N as well as excesses of N. Overall, the results show that the end‐of‐season cornstalk test deserves attention as a tool for providing feedback that can be used to compare and refine systems for making N fertilizer recommendations.
Autumn Sward Suppression and Insect Control Effects on Late‐Winter No‐Till Establishment of Ladino Clover
Authors: Zarnstorff M.E. , Chamblee D.S. , Mueller J.P. , Campbell M.V. 
Published: July 2010

AbstractLadino clover (Trifolium repens L.) has traditionally been established in the autumn in the southeastern USA. Grass suppression and insect control have proven beneficial for successful autumn no‐till establishment. Winter planting offers an alternative, yet little is known about late winter grass suppression and insect or mollusk control. Herbicide applied at planting in late winter usually failed to suppress or kill cool‐season grasses. Field studies were conducted to evaluate (i) the influence of fall suppression or kill with paraquat (1,1'‐dimethyl‐4‐4' bipyridinium ion) of the tall fescue (Festuca arundinacea Schreb.) sward on late‐winter (February or March) no‐till establishment of ladino clover, (ii) establishment by drilling versus surface planting and (iii) the influence of suppression of insect and/or mollusk populations on the late‐winter no‐till establishment of ladino clover into tall fescue. Initial late winter no‐till clover densities were 30% greater for the March as compared to February planting (three experiment average). Drill planting of clover resulted in 2.1 times greater initial clover density (four experiment average) and 1.9 times more clover yield than surface planting (three experiment average). Application of paraquat to tall fescue in bands (13 cm) in mid‐October resulted in essentially complete grass kill with the bands. Neither autumn grass suppression nor the use of insecticide or molluscicide altered clover density or stand. Late‐winter, no‐till establishment provides an alternative to fall establishment. Our results indicate that fall chemical suppression of grass swards is not necessary for successful late‐winter establishment of ladino clover.
Relative Nitrogen Utilization by Legume Cover Crop Species at Three Soil Temperatures
Authors: Power J. F. , Zachariassen J. A. 
Published: July 2010

AbstractWhen selecting a legume cover crop, one should know relative N‐fixing and N uptake capabilities, as well as growth and water use characteristics, to identify the species best adapted to the growth period and soil temperatures (season) during which the cover is crop grown. We provide information on these characteristics for eight inoculated legume species at soil temperatures of 10, 20, and 30 °C. Plants were grown in constant‐temperature water baths in a greenhouse for 105 d after establishment in 1.1 kg of Alliance silt loam (fine silty, mixed, mesic, Aridic Argiustoll) per pot. Plant samples were taken every 21 d for determinations of dry weight, total N uptake, and N2 fixed (isotope dilution method). Water use was measured daily by weighing. Total N uptake and N2 fixation were usually greatest for large‐seeded annual species during the first 42 to 63 d of the experiment. At 10 °C total N uptake and N2 fixation were greatest for hairy vetch (HV), Vicia villosa Roth and faba bean (FB), Vicia faba L. At later sampling dates, N uptake and fixation for white clover (WC), Trifolium repens L., was also relatively high. At 20 °C, soybean (SB), [Glycine max (L.) Merr.] exhibited outstanding growth and N uptake throughout the 105 d. For the first 42 d, FB performance also was superior to other species. At 30 °C, N uptake and fixation by SB was more than double that of any other species at all sampling dates. Quantity of N2 fixed per unit water used was greatest at 10 °C for WC, followed closely by HV and field pea (FP) Pisum sativum L.; at 20 °C, SB followed by WC and lespedeza (LD), Lespedeza stipulacea Maxim.; and at 30 °C, LD followed by SB. Our results suggest that under many situations (early spring) some grain legumes, such as and FB, may be a better cover crop than many species commonly used.