bluuebunny/crossref_metadata_2025 huggingface dataset:
AGROBASE/4: A Microcomputer Database Management and Analysis System for Plant Breeding and Agronomy
Authors: Mulitze D. K.
Published: July 2010

AGROBASE/4 version 1.0 (Copyright (©) 1990 by D.K. Mulitze) is a scientific software application developed in the dBASE IV (Ashton‐Tate, Torrance, CA) compatible FoxPro 1.0 (Fox Software, Perrysburg, OH) database management language for plant breeding and agronomy. AGROBASE/4 supports the design and management of agronomic experiments through randomization (including lattices), file and data management, printing of field books and labels, specialized data transformations for agronomic research, data summarization, and report generation. Statistical support includes analyses of variance, multivariate linear regression, correlation, and descriptive statistics. AGROBASE/4 is being used in small grain, corn (Zea mays L.), food legumes, hop (Humulus lupulus L.), and canola (Brassica napus L., Brassica campestris L.) breeding programs. Support for variety testing and plant breeding programs includes development of germplasm files, pedigree data management (particularly for small grain and corn breeding), genetic analyses, genotype ✕ environment interaction and stability analyses, and multiitrait selection. User‐friendly features include an on‐line manual, help screens, pop‐up utilities, an extensive demonstration mode for new users, and menus. Flexibility is provided via options for customization, user‐programmable procedures, access to MS‐DOS (Microsoft Corp., Boca Raton, FL) and other programs plus most of the 500 FoxPro commands and functions. AGROBASE/4 is designed for users with minimal knowledge of dBASE and also experienced users or programmers. Hardware requirements include a microcomputer capable of running MS‐DOS 2.1 or later with 640 K of RAM and a fixed disk with 1.5 MB free. FoxPro need not be purchased to run AGROBASE/4.
Potassium Fertilizer and Potato Leafhopper Effects on Alfalfa Growth
Authors: Kitchen N.R. , Buchholz D.D. , Nelson C.J.
Published: July 2010

Potassium nutrition can alter plant resistance to environmental stresses. In two glasshouse experiments, the objectives were to assess the effects of K fertility and potato leafhopper (PLH) [Empoasca fubae (Harris)] feeding on mature and young (seven and four regrowth periods prior to PLH infestation, respectively) alfalfa plant (Medicago sativa L.) growth, regrowth, and carbohydrate reserves. Mature plants were grown on Claiborne (fine‐loamy, siliceous, mesic, Typic Paleudult) and young plants on Doniphan (clayey, mixed, mesic, Typic Paleudult) top soil treated with 0, 50, 100, and 200 mg K kg−1 soil. Three harvests were allowed to give K nutrition differences. Female PLHs were released into half of the caged plants for 3 wk for two subsequent harvests. Alfalfa herbage yield, shoot height, root weight, and root total nonstructural carbohydrates (TNC) increased with increasing K fertilizer. With mature plants, herbage yield, root weight, and TNC were reduced by PLH over K rates by 0.3 g plant−1 , 0.36 g plant−1 , and 22 g kg−1 , respectively. Reduction by PLH to young‐plant root TNC was an average of 44 g kg−1 . At the same time, reduction in herbage yield and root weight increased with K fertility. Alfalfa maturity was delayed by the PLH. Susceptibility to PLH injury was greatest with young alfalfa plants. Increased K fertility did not reduce PLH injury in alfalfa; however, alfalfa growth and persistence improved, with or without PLH, with increasing K fertility.
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

Sanborn 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

Phosphorus 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

Ethephon [(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

Irrigated 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

Accurate 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

Opuntia 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

Companion 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

Summer 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

No‐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

Increasing 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

Most 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

Available 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

A 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.
Soil Type and Moisture Regime Effects on Fertilizer Efficiency Calculation Methods in a Nitrogen‐15 Tracer Study
Authors: Torbert H.A. , Mulvaney R.L. , Vanden Huevel R.M. , Hoeft R.G.
Published: July 2010

Research was conducted to determine the extent to which the method of calculation affects estimates of fertilizer N efficiency using 15N as a tracer. Corn (Zea mays L.) was grown at three locations in Illinois that varied widely in soil type. Three early‐season moisture regimes (ambient, ambient + 100 mm of excess water, and ambient + 150 mm of excess water) were established to obtain different fertilizer N efficiencies on each soil. Application of 15N‐enriched KNO3 (168 kg N ha−1) was made to a Drummer silty clay loam (fine‐silty, mixed, mesic Typic Haplaquoll) at DeKalb, a Cisne silt loam (fine, montmorillonitic, mesic Mollic Albaqualf) at Brownstown, and a Plainfield sand (mixed, mesic Typic Udipsamment) at Havana, IL. Fertilizer N efficiency was calculated from the difference between N uptake by fertilized versus unfertilized plants, from the amount of 15N recovered in the plant, and from the recovery of 15N in both the plant and soil. For the Drummer and Cisne soils, the three calculation procedures gave different percent fertilizer N efficiencies when averaged across moisture treatments, and different trends among moisture treatments. For the Plainfield soil, percent fertilizer N efficiency values were lower than those obtained for the Drummer or Cisne soil, and the method of calculation had very little effect. The results indicate that, for most soils, N fertilizer efficiency ratings vary with the method by which they are calculated. The present study demonstrates a need for standard terminology to help identify parameters used to define fertilizer efficiency.
Post‐Anthesis Ethephon Effects on Yield of Spring Barley
Authors: Ma B. L. , Smith Donald L.
Published: July 2010

Ethephon (2‐chloroethyl phosphonic acid) application after heading may enhance the grain yield of cereal crops such as barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) by altering grain‐filling processes. The objective of this study was to evaluate the effects of post‐anthesis (1 wk after heading) ethephon application on variables contributing to the grain yield of spring barley cultivars. A field experiment, with application of ethephon at three rates (0, 240, and 480 g a.i. ha−1) to two barley cultivars, Cadette and Leger, was conducted on Bearbrook clay soil (fine, mixed nonacid, mesic Humaquept) in Quebec, Canada in 1988, 1989, 1990. A post‐anthesis application of ethephon extended the grain‐filling period by 1 to 3 d with variation among both cultivars and years. The 1000‐grain weight of both cultivars significantly increased in all 3 years while no changes were found in the other yield components (spikes per square meter and grains per spike). Grain yield of Leger (conventional stature) was increased 5 to 12% more than unsprayed controls while Cadette (semidwarf) grain yield was either not altered or significantly reduced. These results indicate that under climatic conditions such as those prevalent in northeastern North America post‐anthesis application of ethephon can potentially enhance grain fill and yield of spring barley.
Evaluating Internal Zinc Requirements of Grain Crops by Seed Analysis
Authors: Rashid A. , Fox R. L.
Published: July 2010

Our study tested the general opinion that foliar tissues are superior to seeds for determining the nutrient status of crops. Zinc requirements of leaves and seeds were estimated from yield response curves based on greenhouse pot culture experiments using two Zn‐deficient subsoils (Paaloa silty clay; clayey, oxidic, isothermic Humoxic Tropohumult; and Keahua silty clay loam; fine, kaolinitic, isohyperthermic Torroxic Hapulstoll) of Hawaii. These were fertilized with 0, 1, 3, 9, or 27 mg Zn kg−1 of soil. The order of grain yield response to Zn fertilization was: wheat (Triticum aestivum L.) < sorghum [Sorghum bicolor (L.) Moench] < rice (Oryza sativa L.) < millet [Pennisetum americanum (L.) Schumann] < soybean [Glycine max. (L.) Merr.] < cowpea [Vigna unguiculata (L.) Walp.] < corn (Zea mays L.). Fertilizer Zn requirements for near‐maximum grain yield was highest for cowpea (7.5 mg kg−1 soil) and lowest for wheat (0.5 mg kg−1 soil). Zinc concentrations (mg kg−1) in recently matured leaves associated with 95% maximum yields were similar for seven species: corn and millet, 24; soybean, 22; cowpea, 21; sorghum, 20; rice, 19; and wheat, 17. Equivalent concentrations for seeds were soybean, 43; cowpea, 26; corn, 18; millet, rice and wheat, 15; and sorghum, 10. Across all species, fertilizer levels and soils, the range of Zn concentration in leaves was 5 to 115 mg kg−1 (both values for corn); and in grains 6 (sorghum) to 59 mg kg−1 (wheat). Our results indicate that there was little reason to prefer leaves over grain as a diagnostic tissue for Zn; therefore, Zn should be added to the list of elements for which seed analysis may be advantageous.
Yield, Vegetative Growth, and Fiber Length of Kenaf Grown on Saline Soil
Authors: Francois L. E. , Donovan T. J. , Maas E. V.
Published: July 2010

Kenaf (Hibiscus cannabinus L.) is an excellent supplement to wood as a source of fiber for paper pulp. With the introduction of kenaf into the western USA, plantings may be on soils where salinity problems already exist or may develop from the use of saline irrigation water. Because of the lack of salt‐tolerance information on mature vegetative growth and yield, a 2‐yr field‐plot study was conducted at Brawley, CA. Two cultivars (Everglades‐41 and 7818‐RS‐10) were grown with six salinity treatments imposed on a Holtville silty clay [clayey over loamy, montmorillonitic (calcareous), hyperthermic Typic Torrifluvent]. Electrical conductivities of the irrigation waters, containing NaCl and CaCl2 (1:1 by weight), were 1.1, 2.0, 3.0, 4.0, 5.0, and 6.0 dS m−1. Soil salinity (electrical conductivity of the saturated‐soil extract, Kc) ranged from 5.4 to 12.6 dS m−1 the first year, and from 6.0 to 14.9 dS m−1 the second year. Vegetative growth, stem yield, and fiber length were measured. The mean dry weight yields of the stems during the 2‐yr experiment were reduced 11.6% for each unit increase in soil salinity above 8.1 dS m−1. These results place kenaf in the salt tolerant category. Yield reduction resulted from both a reduction in plant height and stem diameter. Increased salinity did not significantly affect fiber length. Excessive Cl accumulation occurred in the leaf tissues at high soil salinity levels.
Observer Variability for Disk Meter Measurements of Forage Mass
Authors: Aiken G.E. , Bransby D.I.
Published: July 2010

Inconsistency among research workers in estimating forage mass in grazing experiments would limit the value of forage mass estimates, but this problem has not been thoroughly examined. A study was conducted to determine variation among observers in using the disk meter to measure forage mass on tall fescue [Festuca arundinacea (L.) Schreb.] pastures which were grazed by steers (Bos taurus L.) at stocking rates of 2.0, 4.5, and 6.0 animals ha−1. Four observers, with varying degrees of training and experience, were used to visually identify sites which represented mean disk meter height (DMH), determine DMH from random location of DMH measurements, and calibrate the disk meter for estimating forage mass. There was an observer‐by‐stocking‐rate interaction for visual locations of sites considered to represent mean DMH. Slopes differed among observers for the regression of pasture DMH (estimated from randomly located sites) on stocking rate. Slopes for calibration equations also differed among observers. Results of this study indicate inconsistency among observers in using the disk meter to estimate forage mass, suggesting that caution should be taken when extrapolating forage masses from grazing experiments.
Modification of Infiltration Rates in an Organic‐Amended Irrigated
Authors: Martens D. A. , Frankenberger W. T.
Published: July 2010

Slow water infiltration in some California soils results in considerable irrigation water loss through increased runoff and evaporation. This 25‐mo study was conducted to evaluate the effects of different organic amendments on soil physical parameters and water infiltration rates on an irrigated soil. Incorporation of three loadings (25 Mg ha−1 each) of poultry manure, sewage sludge, barley straw (Hordeum vulgare L.), and alfalfa (Medicago sativa L.) to an Arlington soil (coarseloamy, mixed, thermic Haplic Durixeralf) for 2 yr increased soil respiration rates (139‐290%), soil aggregate stability (22‐59%), organic C content (13‐84%), soil saccharide content (25‐41%), soil moisture content (3‐25%), and decreased soil bulk density (7‐11%). The change in soil physical properties resulted in significantly increased cumulative water infiltration rates (18‐25%) in the organic‐amended plots as compared with the unamended plots. Although additions of poultry manure and sewage sludge contributed to higher soil organic matter compared with straw and alfalfa, the straw amendment was statistically more effective in increasing soil aggregate stability, total saccharide content, infiltration rates, and soil respiration rates and in decreasing bulk density in the tillage zone. The increase in cumulative infiltration rates measured with the first organic addition (April 1987–January 1988) were significantly correlated with increased soil aggregation (P ≤ 0.01). Cumulative infiltration rates during the second (February 1988–September 1988) and third (October 1988–May 1989) organic incorporation were significantly correlated with decreased bulk density (P ≤ 0.01), but not with aggregate stability. Multiple linear regression analyses indicated that water infiltration rates in the organic‐amended soils were initially increased by stimulation of microbial activity, which increased the stability of soil aggregates. Cumulative infiltration rates were further increased by a decrease in soil bulk density with additional organic treatments to the tillage zone.
Drought Effects on Perennial Forage Legume Yield and Quality
Authors: Peterson P.R. , Sheaffer C.C. , Hall M.H.
Published: July 2010

Drought frequently limits alfalfa (Medicago sativa L.) herbage productivity during mid‐summer in the North Central USA, but the productivity of other legumes during drought is unknown. We determined the effect of drought on the herbage yield and quality and stand persistence of birdsfoot trefoil (Lotus corniculatus L.), cicer milkvetch (Astragalus cicer L.), red clover (Trifolium pratense L.) and alfalfa. Legumes were established on a sandy, mixed, Udorthentic Haploborolls and subjected to two soil water regimes promoting ‘droughted’ and ‘well‐watered’ (control) plant growth. Mid‐day stem pressure potentials for droughted and control plants ranged from −1.3 to −3.8 MPa and −0.1 to −1.4 MPa, respectively. When drought occurred throughout growth, legume herbage yields of droughted alfalfa, birdsfoot trefoil, cicer milkvetch, and red clover averaged 33, 21, 19, and 13% of their respective controls. Average herbage yield of droughted alfalfa was 120% greater than yields of birdsfoot trefoil and cicer milkvetch, and 165% greater than red clover yield. Averaged for all harvests and species, whole herbage acid detergent fiber (ADF), neutral detergent fiber (NDF), and acid detergent lignin (ADL) concentrations were reduced by 30 to 4870, 26 to 46%, and 0 to 49%, respectively, when drought occurred throughout growth. Effects of drought on lignin in NDF and crude protein concentration were not consistent. Droughted alternative legumes produced herbage with lower ADF, NDF, and ADL concentrations than alfalfa. Improved quality in droughted legumes was related to greater leaf:stem weight ratio, delayed maturity, and often higher quality in both the leaf and stem fractions compared to the control treatment. Although drought reduced the herbage yield of all legumes, alfalfa has the greatest yield potential in drought.
Mepiquat Chloride and Irrigation versus Cotton Growth and Development
Authors: Reddy V. R. , Trent A. , Acock B.
Published: July 2010

Cotton (Gossypium hirsutum L.) produces excessive vegetative growth when grown under optimum water and nutrient conditions. The plant growth regulator Mepiquat Chloride (MC); 1,l‐dimethyl piperidinium chloride reduces vegetative growth and can promote early maturity. Its effect on yield has been inconsistent, with some researchers showing an increase while others have indicated a decrease. This variation in yield has often been attributed to environmental factors and variations in water and fertilizer inputs. This study examined the effect of MC on cotton growth, under varying irrigation treatments, to determine if soil moisture interacts with MC. The experiment was conducted in 1987 with two cotton cultivars, Stoneville 825 (‘ST825’) and Deltapine 20 (‘DP20’), grown in pots, with five irrigation treatments [1.2,1.0,0.8,0.6, and 0.4 times previous day's pan evaporation (PE)] each with and without MC applied. Mepiquat Chloride reduced plant height, number of main stem nodes, and internodal length. The effect on boll numbers was mixed between cultivars. In some instances under the same irrigation treatment (1.2 PE), the number of bolls was higher in ST825 with MC applied than with control while in DP20 the control treatment had the higher number of bolls. Mepiquat chloride's effectiveness on vegetative growth tended to decrease as the number of days after application increased. Differences in response within irrigation treatments was attributable to MC. Differences in response between irrigation treatments with MC applied was attributable to irrigation and cultivar differences and not to interaction between soil moisture and MC.
Chlormequat and Ethephon Timing and Grain Production of Spring Barley
Authors: Ma B. L. , Smith Donald L.
Published: July 2010

Several plant growth regulators increase the number of spike‐bearing tillers and have potential as lodging control agents for spring barley (Hordeum vulgare L.). The objective of this study was to evaluate the effects of chlormequat (2‐chloroethyl trimethylammonium chloride, CCC) and ethephon (2‐chloroethyl phosphonic acid) timing on yield components, grain yield, and agronomic traits. A 4‐yr field study using the cultivars, ‘Leger’ and ‘Cadette’, was conducted on Bearbrook clay soil (fine, mixed nonacid, mesic Humaquept) at McGill University, in Quebec, Canada, from 1987 to 1990. Treatments consisted of application of CCC (1.2 kg ai. ha−1) and ethephon (0.48 kg ai. ha−1) at Zadoks growth stages (ZGS) 13, 30, and 39. Yield components were measured on a plot and a spike basis with separation of spikes into main culms and tiller culms. Early application of CCC at ZGS 13 enhanced grain number per spike, hut not grain yield due to compensations among yield components. At ZGS 30, ethephon application increased tiller‐derived spikes per square meter up to 265% compared to the unsprayed control, while treatment with CCC increased Leger grain yield by more than 10% in two of the 4 yr of this study. This yield increase was attributable to a slight increase in the number of grains per spike−1. Ethephon applied at ZGS 39 reduced plant height and lodging, but decreased yield by up to 27% because of reductions in the number of grains per spike, the main culm spike number, and/or weight per grain. These results indicate that in regions with a short crop‐growing season, where lodging is uncommon, early application of CCC or ethephon is not justified for grain production, and that caution must be taken when applying ethephon to spring barley at the currently recommended rate and stage for lodging control.
The Return of von Liebig's “Law of the Minimum”
Authors: Paris Q.
Published: July 2010

The development of optimal fertilizer recommendations requires a renewed collaborative effort between agronomists and agricultural economists. The purpose of this study is to emphasize the direction of this interdisciplinary effort in the area of crop response analysis. Using information from two separate experiments [corn (Zea mays L.) response to N and P fertilization and cotton lint (Gossypium hirsutum) response to N and irrigation water], it is shown that the best response model is a von Liebig specification, more commonly known as the law of the minimum. When the selection of a statistical specification is made among models that do not share the parameter space, hypothesis testing cannot be done by means of the familiar F‐test and likelihood ratio. The selection of the von Liebig specification (chosen against square‐root polynomial and Mitscherlich‐Baule models) is, thus, made on the basis of a rigorous statistical analysis using a nonnested hypothesis approach.
Performance of a Superior Bradyrhizobium japonicum and a Selected Sinorhizobium fredii Strain with Soybean Cultivars
Authors: Ravuri V. , Hume D. J.
Published: July 2010

Strain 532C of Bradyrhizobium japonicum has outperformed other soybean [Glycine max (L.) Merr.] rhizobial strains in Ontario trials conducted with cv. Evans. Strain HH303 of Sinorhizobium fredii has proven effective with some Ontario cultivars. The objective of this research was to compare the performance of 532C with that of USDA 110, CB 1809, a three‐strain mixture, and HH303, by 16 commonly‐grown, early‐maturing soybean cultivars. Trials were conducted from 1988 to 1990 (only five cultivars were used in 1990) on soils that had low available N and had not grown soybeans previously. There were significant (P < 0.01) strain‐by‐genotype interactions for yield in all 3 yr and for seed protein content in 1988 and 1989, but interactions were small compared to main effects. Averaged over cultivars, strain 532C caused 11 to 17% higher seed yield than USDA 110 or CB 1809 in all 3 yr. Strain 532C appeared effective with all 16 cultivars tested. Strain 532C, used alone, caused higher average yields than the three strain mixture, which included 532C, only in 1988. The S. fredii strain HH303 caused consistently lower average yields than 532C, USDA 110, and the three‐strain mixture, but average yields with HH303 and CB 1809 were not different in 1988 and 1989. Cultivars with cv. Evans in their pedigree yielded well with HH303. There were strong positive correlations (r = 0.75−0.85) between seed yield and seed protein contents. Strain 532C supported higher seed yields than the three‐strain mixture at equivalent seed protein contents. Strain 532C was an effective N2 fixer with all cultivars tested and is now used in all soybean inoculants sold in Ontario.
Interrelationships among Turfgrasses, Clipping Recycling, Thatch, and Applied Calcium, Magnesium, and Potassium
Authors: Sartain J. B.
Published: July 2010

The influence of clipping return on bermudagrass thatch has not been resolved. Additionally, independent and combined effects of applied Ca, Mg, and K on bermudagrass growth and quality and thatch accumulation have not been clarified. To evaluate the influence of clipping return and applied Ca, Mg, and K on ‘Tifway’ bermudagrass (Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt Davy) and ‘Pennant’ perennial ryegrass (Lolium perenne L.) a 3‐y study was conducted at the Turfgrass Field Laboratory near Gainesville, FL, on an Arredondo loamy fine sand (Typic Quartzipsammets). A strip‐split‐plot factorial experiment with applied Ca, Mg, and K at 20 g m−2 representing the main plot and with clipping return or removal stripped across the main plots with three replications was employed. Bermudagrass clipping return did not affect overall mean thatch accumulation. Bermudagrass and perennial ryegrass clipping yields increased in response to clipping return. Bermudagrass quality was enhanced by the return of clippings, but ryegrass quality was not. Application of Ca and K did not influence thatch accumulation, while Mg did promote additional bermudagrass thatch. Application of K and Mg reduced Ca levels on plots receiving Ca to less than the extractable Ca level of the untreated plots. Ryegrass and bermudagrass quality was increased by the application of Mg on plots which had the clippings removed. Potassium and Mg application promoted bermudagrass clipping yield when clippings were removed. Soil Ca to Mg ratio did not influence the growth or quality of either bermudagrass or ryegrass.
Seeding Rate, Nitrogen Fertilization, and Irrigation Effects on Floral Meadowfoam Oil Yield
Authors: Jolliff G. D. , Seddigh M. , Norberg O. S. , Fiez T. E.
Published: July 2010

Increased rates of seeding and N fertilization have accounted for higher yields with new cultivars of several crops. Our objective was to evaluate the new meadowfoam cv. Floral (Limnanthes floccosa Howell subsp. grandiflora Arroyo) × Oregon Limnanthes ORL77‐84 (L. alba Hartw. ex Benth. subsp. alba). Combined effects of seeding rate (1.5, 4.0, and 6.5 million seeds ha−1), February applied N topdress rate (0, 80, and 160 kg ha−1), and irrigation (none, pre‐bloom, and pre‐ and post‐bloom) were evaluated near Corvallis, Oregon in 1987–1988 and 1988–1989. Seeding rate, N rate, and irrigation effects on all measured variables were independent of each other. Seed yield, seed oil content, and oil yield increased 45, 5, and 50%, respectively, while lodging did not increase as seeding rate increased from 1.5 to 6.5 million seeds ha−1. Increased flower number was the main reason for seed yield improvement when seeding rate was increased. Seed yield, seed oil content, and oil yield decreased slightly when N rate increased from 0 to 80 kg ha‐1, and dropped sharply at 160 kg N ha−1, with severe lodging. The highest average yields of seed (1684 kg ha−1) and oil (542 kg ha−1) were achieved with the combination of the highest seeding rate, lowest N fertilizer rate, and pre‐bloom irrigation.