bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Soil. Loss after 100 Years of Soil and Crop Management
Authors: Gantzer C. J. , Anderson S. H. , Thompson A. L. , Brown J. R. 
Published: July 2010

AbstractSanborn Field, at the University of Missouri‐Columbia was established in 1888 and is the oldest agricultural experiment field west of the Mississippi River. It provides an excellent opportunity to document how long‐term crop rotations, and soil management influence soil erosion. Analyses of topsoil thickness are presented to describe soil remaining after 100 yr of cropping in plots planted to continuous corn (Zea mays L.), to continuous timothy (Phleum pratense L.), and to a 6‐yr rotation cropped sequentially to corn, oat (Avena sativa L.), wheat (Triticum aestivum), clover (Trifolium pratense), timothy, and timothy. Topsoil thickness was significantly less for the continuous corn than the 6‐yr rotation or timothy plots after 100 yr of cropping. Corn plots had only about 44%, and the rotation plots had only about 70% as much topsoil as did the timothy plots. The amount of clay in the plow layer was significantly higher in the corn plots compared to either the rotation or timothy plots suggesting that mixing of clay subsoil within the plow layer occurred in corn plots.
Buildup and Decline in Soil Phosphorus: 30‐Year Trends on a Typic Umprabuult
Authors: McCollum R. E. 
Published: July 2010

AbstractPhosphorus reserves in Ultisols are inherently low; but many Ultisols along the Atlantic seaboard are now high in P, both extractable and total, because P additions have exceeded P removal for many years. How long a high‐P soil will maintain plant‐available P above yield‐limiting levels is of agroeconomic relevance. A field experiment initiated 35 yr ago on Portsmouth soil (fine sandy over sandy or sandy‐skeletal, mixed, thermic Typic Umbraquult) and monitored for crop yields and soil‐test P (Mehlich‐1 extractant) during 8 yr of active P buildup and 26 yr of residual decline has provided quantitative data on this issue. Yields of corn (Zea mays L.) or soybean [Glycine max (L.) Merr.] were maximal with soil‐test P ≥ 22 g m−3, and extractable P was maintained in this range (20‐24 g m−3) when P removed in harvested products (16 kg ha −1 yr−1) was replaced annually as band‐applied fertilizer. High soil‐test levels (≥50 g m−3) could not be maintained by annual replacement of crop‐removed P because P reversion to unextractable forms was a larger factor than crop removal in depleting the extractable‐P pool. Regardless of initial level, P disappearance into these unextractable forms was best described via equations having the form of a first‐order chemical reaction; but the magnitude of the rate constant varied with size of the extractable‐P pool, i.e., high‐P soils have large rate constants; low‐P soils have small rate constants. A Portsmouth soil testing 50 to 60 g P m−3 today will test above 22 g m−3, the approximate critical level for corn, for the next 8 to 10 yr without further P additions. Doubling the initial soil test will not double the time to reach yield‐limiting P levels, however; the same soil with 100 to 120 g P m−3 initially will drop to 22 g m−3 in about 14 yr.
Barley Treated with Ethephon: II. Tillering Pattern and its Impact on Yield
Authors: Moes J. , Stobbe E. H. 
Published: July 2010

AbstractEthephon [(2‐chloroethyl)phosphonic acid] used for lodging protection in barley (Hordeum vulgare L.) often increases spikes m−2. The degree to which such additional spikes contribute to yield has not been reported, and neither has the source of such spikes been determined. This study was undertaken to determine the effects of ethephon on tiller emergence and survival, as well as the contribution to yield of additional spikes appearing on ethephon treated barley plants. Ethephon was applied at Zadoks growth stage (GS) 35 and/or 45 at 240 g ha−1 to ‘Argyle’ conventional height and ‘Samson’ semidwarf barley grown at 100 and 300 plants m−2 at Winnipeg, MB. Ten plants per plot were observed at intervals through the growing seasons; tillers were tagged as they emerged and their contributions to spikes per plant and grain yield were determined at harvest. The two cultivars responded similarly to ethephon application. In all 3 yr and at both plant densities, ethephon application increased shoots per plant. Application at GS 45 increased shoots per plant more than at GS 35 in 1987 when moisture was adequate, but less in 1988 when some moisture stress may have affected barley at GS 45. Late appearing shoots contributed up to 32 and 15% of spikes per plant and grain yield per plant, respectively, for both plant densities in 1987 and for the low plant density in 1989. Increased spikes per plant due to ethephon application were attributable to late tiller production and survival rather than to prevention of senescence of early formed tillers. The increase of spikes per plant by ethephon should be a positive influence on grain yield, but total yield per plant was often decreased and was never increased by ethephon because ethephon also caused reductions in kernels per spike.
Grazed Wheat Grain Yield Relationships
Authors: Winter S.R. , Musick J.T. 
Published: July 2010

AbstractIrrigated wheat (Triticum aestivum L.) in Texas is grown in early‐planted production systems that are grazed by stocker cattle (Bos spp.) and late‐planted nongrazed production systems. The objectives were to: (i) verify cultivar ✕ production system interactions for 11 cultivars in 1988 and (ii) better understand grain yield relationships using data from 1986 experiments involving two semidwarf cultivars, Q588 and Vona, and the taller Siouxland. Average grain yield loss in 1988 due to grazing (grazed vs. nongrazed system) was 0.52, 1.37, and 2.18 Mg ha−1 for tall, intermediate, and short cultivars, respectively. Responses within height classes were consistent for three tall cultivars and five short cultivars. In the nongrazed production system in 1986, Q588 and Vona were better adapted as shown by linear increases in seed number and grain yield at anthesis biomass levels up to 1600 g m−2. In contrast, Siouxland a taller cultivar did not increase seed number or grain yield when biomass exceeded 1300 g m−2. Severe or later grazing reduces height, leaf area, and biomass. Under these less productive conditions, Siouxland yielded as much as Q588 or Vona. The cultivar ✕ system interaction is caused by the greater response of semidwarf cultivars to productive nongrazed systems coupled with the size advantage of tall cultivars in grazed systems. As a result, the yield advantage of semidwarf cultivars over tall cultivars is much greater in nongrazed as compared to grazed system.
Phenological Analysis of Forage Yield and Quality in Winter Wheat
Authors: West C. P. , Walker D. W. , Bacon R. K. , Longer D. E. , Turner K. E. 
Published: July 2010

AbstractAccurate predictions of forage quality of winter wheat (Triticum aestivum L.) during spring would allow targeting of harvests or grazings to desired levels of nutritive composition to meet specific animal requirements. The objectives of this study were to compare number of days since 15 February (DAYS) and growing degree days (GDD, base 4.4 °C) as predictors of Feekes and Zadoks growth stages, and to compare DAYS, GDD, Feekes, and Zadoks growth stages as predictors of forage yield and quality. The 2‐yr study on a Captina silt loam (fine, mixed, mesic, Typic Fragiudult) at the University of Arkansas Main Experiment Station, Fayetteville, AR, involved four cultivars of soft red winter wheat. Plots were harvested at six growth stages: beginning of pseudostem elongation, second node detectable, flag leaf collar just visible, boot swollen, inflorescence completely emerged, and soft dough. Feekes and Zadoks growth stage scales were regressed on DAYS and GDD. Forage yield, percentage lamina (ratio of leaf lamina to whole‐plant dry weight), and nutritive concentrations were regressed on Feekes, Zadoks, DAYS, and GDD. Lower root error mean squares were generally obtained with GDD than DAYS for predicting growth stages. Zadoks scale and DAYS were generally the best predictors of forage yield, whereas Feekes scale and DAYS were the best predictors of percentage lamina and crude protein. Zadoks and GDD were the best predictors of neutral detergent fiber and in vitro dry matter digestibility. The Zadoks scale and GDD would be useful parameters in wheat growth models designed to target harvests to desired levels of forage quality.
Growth and Predicted Productivity of Opuntia ficus‐indica for Current and Elevated Carbon Dioxide
Authors: Nobel Park S. , de Cortázar Victor Garcia 
Published: July 2010

AbstractOpuntia ficus‐indica (L.) Mill., a prickly pear cactus cultivated worldwide for its fruits and stem segments, can have an annual dry weight productivity exceeding that of many crops. Using a recently introduced environmental productivity index (EPI), the influences of water status, temperature, and photosynthetically active radiation (PAR) on its productivity can be predicted. This investigation calculated the water index, the temperature index, and the PAR index, whose product equals EPI, for 169 sites distributed approximately uniformly across the contiguous USA for present climatic conditions as well as for those associated with an elevated CO2 concentration of 650 µL L−1. The effect of elevated CO2 on growth of O. ficus‐indica was directly measured, and low temperature limitations on productivity were considered. The dry weight gain of O. ficus‐indica during 6 mo in an environmental growth chamber was 23% greater at 650 compared with 350 µL L−1 CO2 and increased as the duration of the wet period increased, in agreement with predictions of the water index (the fraction of maximal net CO2 uptake during a 24‐h period for the prevailing plant water status). For closely spaced plants that lead to a high productivity per unit ground area, EFI averaged about 0.10, except in desert regions where the water index lowered EPI, in the far North or South and at high elevations where the temperature index lowered EPI, and in the Northeast and Northwest where the PAR index lowered EPI. The predicted annual dry weight productivity for O. ficus‐indica was 12.8 Mg ha−1 yr−1 under current conditions, and 16.3 Mg ha−1 yr−1 under those associated with 650 µL L−1 CO2. Both productivities are relatively high compared with other agronomic plants. The percentage of sites where temperatures fall below −15 °C at least once during the 10 years simulated, which would be lethal to most prickly pear cacti, was reduced frori 49 to 18% by the general warming expected to accompany an approximate doubling of the atmospheric CO2 concentration
Oat Companion Crop Seeding Rate Effect on Alfalfa Establishment, Yield, and Weed Control
Authors: Lanini W. Thomas , Orloff Steve B. , Vargas Ronald N. , Orr Jack P. , Marble Vern L. , Grattan Stephen R. 
Published: July 2010

AbstractCompanion crops have been used in alfalfa (Medicago sativa L.) establishment to increase forage yield and decrease weeds. When oat (Avena sativa L.) is used as a companion crop, the typical seeding rate is 50 to 75 kg ha−1. In irrigated situations this seeding rate has depressed alfalfa yield and stand density. This study was conducted under irrigated conditions to evaluate alfalfa yields, forage composition at first harvest, and alfalfa and weed densities at four oat seeding rates; 0 to 36 kg ha−1. Two field experiments were established at Madera and one at Courtland, CA. The interplanting of oat with alfalfa increased first‐harvest forage yields 2.45 to 8.62 Mg ha−1, relative to alfalfa planted alone. Alfalfa yields at subsequent cuttings during the first season were reduced by the oat companion crop. By the last cutting in the first season and all cuttings in the second season, yields were equal for all treatments. First‐season forage yields were increased 1.54 to 5.05 Mg ha−1 by an oat companion crop. The oat component of the first cutting ranged from 71 to 98%. Alfalfa and weed biomass were both reduced by the oat companion crop. The oat companion crop reduced alfalfa stand density during establishment, but density was higher at the beginning of the second season at two of the three sites when the oat seeding rate was 18 kg ha−1. Alfalfa established with an oat companion crop had an average of 30% fewer weeds in the second year when 9 kg ha−1 were used and almost 50% fewer weeds at 18 kg−1. Thus, the seeding rate of an oat companion crop considered best for optimizing yields and reducing weeds under irrigation in California is approximately 18 kg ha−1.
Summer Patch and Kentucky Bluegrass Quality as Influenced by Cultural Practices
Authors: Davis D. B. , Dernoeden P. H. 
Published: July 2010

AbstractSummer patch, caused by Magnaporthe poae Landschoot and Jackson, is among the most destructive diseases of Kentucky bluegrass (Poa pratensis L.). While fungicides may reduce disease severity, information regarding the impact of cultural practices on this disease is unavailable. Hence, the objectives of this field investigation were to examine the effect of irrigation practice [light frequent (LF) versus deep infrequent (DI) irrigation); mowing height (3.8 versus 7.6 cm); and N source (urea, sulfur coated urea, ammonium chloride and sodium nitrate) on summer patch incidence and severity, and turf quality. The study was conducted on a stand of ‘S‐21’ Kentucky bluegrass grown on a Chillum silt loam (fine silty, mixed mesic Typic Hapludult). The effects of these cultural parameters on root biomass, total nonstructural carbohydrate (TNC) content of crown tissue, leaf tissue N, and soil temperature also were evaluated, and their relationship to summer patch incidence and severity is discussed. Turf maintained at 7.6 cm was damaged less by summer patch, exhibited better overall quality, and stored higher TNC levels than turf maintained at 3.8 cm. In 1987 when disease pressure was extremely high, turf subjected to DI irrigation and maintained at 7.6 cm exhibited higher quality and lower summer patch incidence than any other irrigation‐by‐mowing‐height combination. Severely damaged turf allowed to grow from 3.8 to 7.6 cm recuperated more rapidly from disease injury than turf maintained continuously at 3.8 cm. Turf fertilized with sulfur coated urea generally exhibited best quality in 1987 and 1988, and was injured less by summer patch in 1987.
No‐till Winter Wheat Production: Response to Spring Applied Nitrogen Fertilizer Form and Placement
Authors: Johnston A. M. , Fowler D. B. 
Published: July 2010

AbstractNo‐till seeding into standing stubble immediately after harvest of the previous crop has permitted the successful production of winter wheat (Triticum aestivum L.) on the Canadian prairies. In the present study, 14 field trials were conducted in Saskatchewan between 1986 and 1988 to evaluate the influence of the spring broadcast and the surface banded N fertilizer forms ammonium nitrate (AN), urea, and urea‐ammonium nitrate (UAN) solution on grain yield (GY), grain‐protein yield (GPY), and grain‐protein concentration (GP) of no‐till winter wheat. In trials with positive N response, early broadcast urea, surface dribble‐banded UAN, and broadcast spray UAN produced GY(GPY) responses that were 90(91), 89(87), and 82(80)%, respectively, of those observed for early broadcast AN. Accumulated surface residues and delayed early spring (May) rainfall reduced the performance of UAN when applied as a broadcast spray. In one trial, the earlly stimulation of N uptake and growth with early AN proved detrimental under high temperature stress during stem elongation resulting in negative GY and GPY responses with increasing N rate. Delaying broadcast N application by 3 wk prevented early N uptake, reducing both GY and GPY and increasing GP. The results of this study suggest that the reduction in N recovery from commercial rates of urea‐based fertilizers, as measured by GPY, can be minimized at uniform levels by ensuring early spring application on no‐till winter wheat in western Canada.
Crop Rotation and Tillage Effects on Corn Growth and Soil Structural Stability
Authors: Raimbault B.A. , Vyn T.J. 
Published: July 2010

AbstractIncreasing concerns about soil degradation with continuous corn (Zea mays L.) production and a scarcity of scientific information regarding corn grown in rotation with the diversity of crops produced in Ontario, prompted a long term study on the effect of various crop rotations and their interaction with two tillage systems on corn growth and soil structure. Eight rotations were established in 1980 which included continuous corn, six rotations comprised of 2 yr of corn following 2 yr of another crop or crop sequence, and continuous alfalfa (Medicago sativa L.). Each rotation was divided into either conventional tillage (fall moldboard plow) or minimum tillage (fall chisel plow). First‐year corn grown in rotation yielded 3.9% more than continuous corn for conventional tillage and 7.9% more than continuous corn for minimum tillage. These corn responses to rotation were smaller than most of those reported in the literature. When barley (Hordeum vulgare L.) or wheat (Triticum aestivum L.) were the preceding crops, interseeding red clover (Trifolium pratense L.) increased first year corn yields only on conventionally tilled plots. Corn plant development was consistently slower with minimum tillage compared to conventional tillage. Yields were significantly lower with minimum tillage for continuous corn and where corn followed wheat interseeded with red clover. Little or no response to rotation was observed in second‐year corn. The seedbed with continuous corn had a lower proportion of fine aggregates compared to corn grown in rotation. In most years soil aggregate stability was highest under continuous alfalfa and including a legume (whether alfalfa or interseeded red clover) in the rotation improved aggregate stability compared to continuous corn.
Plant Traits Associated with Grazing‐Tolerant Alfalfa
Authors: Brummer E. C. , Bouton J. H. 
Published: July 2010

AbstractMost alfalfa (Medicago sativa L.) cultivars cannot withstand longterm, continuous grazing. This study was conducted to determine if plant morphological traits differ among alfalfa cultivars and populations that vary in persistence under grazing stress. Hay‐type cultivars (Apollo and Florida 77), grazing‐type cultivars (Spredor II, Travois, and Alfagraze), and populations derived from these cultivars that survived continuous grazing for l or 2 yr were space‐planted in the field in 1987 and 1988. Plants were clipped biweekly for 16 wk. Decumbency, stem number and diameter, crown area, and herbage yield were measured at five 4‐wk intervals (Dates 1‐5). Crown buds were counted in the fall. Original populations from Spredor II and Travois had thinner stems, more decumbent growth, lower herbage yield, and more stems (at Date 1) when compared with populations from Florida 77 and Apollo. Alfagraze had many, thick stems, intermediate decumbency, and high herbage yield, indicating these traits can be realized along with grazing tolerance. Alfagraze and Travois had the most crown buds. Selected plants of some cultivars had fewer stems and more decumbent growth initially, but differed little from their original populations for these traits after 120 d of frequent clipping. Year‐2 selections from Sprdor II and Florida 77 had more crown buds than their original populations. Genetic coefficients of variation suggested that selection had resutled in little reduction in genetic variation and that further selection for all traits may be possible in each cultivar.
Nitrogen Fertility Influence on Water Stress and Yield of Winter Wheat
Authors: Nielsen D. C. , Halvorson A. D. 
Published: July 2010

AbstractAvailable soil water and N fertility are the primary factors limiting dryland winter wheat (Triticum aestivum L.) yields in the Central Great Plains. The objective of this field study was to determine how the level of N fertilization influences water use, water stress, and yield of dryland winter wheat grown in this area. The study was conducted during the 1988 and 1990 growing seasons on a Platner loam (fine, montmorillonitic, mesic Aridic Paleustoll) near Akron, CO. Nitrogen fertilizer was broadcast as NH4NO3 at 0, 28, 56, 84, and 112 kg N ha−1. Canopy temperatures were measured with an infrared thermometer and used to compute the crop water stress index (CWSI). Evapotranspiration was computed and rooting depth inferred from weekly neutron probe readings of soil water content. In general, plant height, above‐ground biomass, leaf area index, rooting depth, water use, and grain yield increased with increasing N. Values of CWSI declined after rain and increased as soil water again became limiting. Nitrogen treatment effects on CWSI varied with the severity of water stress. When CWSI <0.38, increasing N rate decreased water stress because a slight increase in rooting volume resulted. When CWSI >0.38, increasing N rate increased water stress because the excessive transpirational demand of the resulting larger leaf area and vegetative mass was not fully compensated by the increased rooting volume. Grain yield averaged over the 2 yr increased with increasing N up through the 56 kg ha−1 rate. The effect of N fertility on water use efficiency (WUE) was significantly different between years, with WUE increasing with increasing N up through the 56 and 84 kg ha−1 rates in 1988 and 1990, respectively. Grain yield was linearly correlated with cumulative evapotranspiration. Increasing levels of N fertility can be detrimental to winter wheat yields when water‐limiting conditions reduce evapotranspiration rates to less than 62% of potential evapotranspiration.
Describing and Quantifying Growth Stages of Perennial Forage Grasses
Authors: Moore K. J. , Moser L. E. , Vogel K. P. , Waller S. S. , Johnson B. E. , Pedersen J. F. 
Published: July 2010

AbstractA system for identifying and quantifying the stages of growth and development of perennial forage grasses was developed. The system consists of a universal set of morphological descriptors for forage and range grasses and a continuous numerical index. The life cycle of individual grass tillers is divided into five primary growth stages (i) germination, (ii) vegetative, (iii) elongation, (iv) reproductive, and (v) seed ripening. Substages corresponding to specific morphological events are defined within each primary stage. Each growth stage consists of a primary and secondary stage and has both a mnemonic code and numerical index associated with it. The codes were designed to be easily memorized and are useful for applying the system in the field. The numerical index is included so that the stages can be expressed quantitatively.