bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality of Whole Crop and Pressed Forage from Mechanically Dewatered Alfalfa, Red Clover, and Birdsfoot Trefoil
Authors: Collins Michael
Published: July 2010

Forage harvesting techniques that reduce losses in yield and quality that normally occur during field wilting of silage and curing of hay are needed. A 2‐yr field study was conducted to evaluate mechanical dewatering of first‐cutting forage of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus corniculatus L.) harvested at four stages of maturity. Each species, grown on Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudolls), was harvested at weekly intervals beginning on 27 May 1980 and 26 May 1981, and the forage was macerated and pressed at 6.9 × 105 Pa for 2 min. Samples of the whole crop collected immediately after cutting and of the pressed forage were dried at 55°C to constant weight. Birdsfoot trefoil was the highest in N concentration of the three whole crops, and red clover was higher in N than alfalfa in 1 of the 2 yr. Pressed forage of alfalfa averaged 6.0 g kg−1 less N than the whole crop. Pressed forage averaged 106, 151, and 49 g kg−1 more neutral detergent fiber (NDF) than whole crop for alfalfa, red clover, and birdsfoot trefoil, respectively. Birdsfoot trefoil in vitro dry matter disappearance (IVDMD) was affected least by Pressing, and red clover IVDMD was affected most. Results of this 2‐yr experiment indicate that mechanical dewatering reduced IVDMD and generally N, and increased NDF concentration. Differences in legume species response to pressing were substantial and would preclude generalization of mechanical dewatering responses across species. However, whole crop dry matter, N, and IVDMD predicted 0.81 or more of the variation in pressed forage IVDMD of the three species, indicating that pressed forage IVDMD can be accurately predicted from whole crop composition.
Phomopsis Seed Infection and Nutrient Accumulation in Pods of Soybean with Reduced Fruit Loads
Authors: Thomison P. R. , Jeffers D. L. , Schmitthenner A. F.
Published: July 2010

Active infection of soybean [Glycine max (L.) Merr.] fruits by Phomopsis longicolla Hobbs is associated with physiological changes occurring during senescence. The purpose of this research was to determine the relationship of carbohydrate and mineral nutrient composition of pod tissue to seed infection by P. longicolla. Varying carbohydrate and mineral nutrient levels in pod tissue were created by different fruit removal and debranching treatments. Reducing fruit load in plants from three to four pods per node to one per node increased seed infection by P. longicolla 42% and decreased seed germination 35%. Total nonstructural carbohydrates, N, and P concentrations in pod walls at physiological maturity were increased 56, 40, and 77%, respectively, by pod reduction. Seed total nonstructural carbohydrates were reduced 13% and seed N increased 15% by reduced fruit loads. Fruit removal delayed plant maturation up to 2 to 3 wk. A lower incidence of P. longicolla and moldy seed from upper nodes (vs. lower nodes) of plants was associated with lower K and greater Ca and total nonstructural carbohydrates in pod walls. Decreasing seed infection by P. longicolla might be achieved by maximizing fruit loads and shortening the time interval between physiological maturity and harvest maturity.
Calcium Deficiency in Sorghum Grown in Controlled Environments in Relation to Nitrate/Ammonium Ratio and Nitrogen Source
Authors: Murtadha H. M. , Maranville J. W. , Clark R. B.
Published: July 2010

Sorghum [Sorghum bicolor (L.) Moench] grown under growth chamber and greenhouse conditions often develops Ca deficiency. Since information on factors affecting Ca uptake and distribution in sorghum is limited, experiments were conducted to better understand factors associated with the enhancement of this disorder. Sorghum genotypes ‘Redlan’ and ‘Martin’ were grown in a growth chamber with 21.4 mM N (300 mg L−1) at NO−3/NH+4 ratios of 300:0, 250:50, 200:100, and 150:150, with Ca levels of 1.25 or 2.50 mM(50 or 100 mg L−1, respectively) to determine the effects of these N ratios on sorghum growth in nutrient solution and the occurrence of Ca deficiency. The same genotypes and conditions were used in a N source experiment where NO−3, NO−3/NH+4 (1:1), NH+4, and urea were compared. Symptoms of Ca deficiency were visible on young leaves of plants grown in solutions containing high proportions of NO+4 and low levels of Ca, but not with NO−3 only or urea. The pH of solutions in the NO−3/NH+4 ratio experiment were higher with NO−3 as the predominate N source. Growth and Ca concentrations decreased but total plant N concentrations increased with high proportions of NH+4 in the treatment solutions and with decreased Ca levels. Thus, N/Ca ratios increased progressively as the proportion of NH+4 in the nutrient solution increased, which also corresponded to increasing severity of Ca deficiency observed on leaves. Lower leaves had higher Ca concentrations than upper leaves indicating the relative immobility of Ca in sorghum. When comparing N sources, plants grown with NO−3 or urea as the sole source of N generally had the best growth and the highest Ca concentrations, followed by plants grown with 1:1 NO−3/NH+4, and NH+4 only, respectively. Dry matter yields increased with increasing solution Ca levels regardless of N source. The enhance uptake of Ca in sorghum when grown with only NO−3 is believed to occur partially as a mechanism to counterbalance anion absorption and maintain proper cation/anion balance. It is likely that a reduction in Ca concentration in plants grown with high NH+4 was partially a result of reduced solution pH exerting antagonistic effects on Ca absorption or releasing Ca from cell wall anionic sites. Reduced and abnormal root growth resulting from high solution NH+4 may have enhanced the appearance of Ca deficiency symptoms by reducing Ca uptake due to reduced absorbing surface or lack of root tip growth.
Survival of Guayule Transplants with Different Methods of Establishment
Authors: Mulkey J. R.
Published: July 2010

For guayule (Parthenium argentatum Gray) to develop as a competitive crop in areas suitable for dryland production, information is needed on methods to establish acceptable stands. The objectives of this experiment were to evaluate the effects of planting method, application of an antitranspirant, and the addition of small volumes of water at planting on the survival of guayule transplants under dryland conditions. The study was conducted on a Uvalde silty clay loam (fine, mixed, hyperthermic Aridic Calciustoll). Planting method, antitranspirant, and moisture level at planting significantly affected transplant survival. Plant survival rates were reduced when transplants were sprayed with an antitranspirant at planting. The addition of water at planting did not significantly affect the survival of transplants with root balls. Survival rates were significantly higher for transplants without root balls that received 200 mL of water per seedling at planting compared to transplants that received no water. A transplant survival rate of 93% or greater was achieved for transplants with root balls, and for transplants without root balls when a small volume of water was applied at planting.
Nitrogen Fixation in a White Clover‐Fescue Pasture Using Three Methods of Nitrogen‐15 Application and Residual Nitrogen‐15 Uptake
Authors: Labandera C. , Danso S. K. A. , Pastorini D. , Curbelo S. , Martin V.
Published: July 2010

It is essential that the 15N source and method of labeling should not introduce significant errors into the estimation of N2 fixed in plants. This study, which was conducted in 1984 and continued in 1985, compares N2 fixation measurements based on the repeated or rotated application of 15N‐labeled (NH4)2SO4 on plots of white clover (Trifolium repens cv. Zapican)‐fescue (Festuca arundinacea cv. Tacuabe) sward with values obtained from plants that relied solely on residual 15N uptake. The soil used was a Typic Hapludoll, pH 6.9. The percentage of N fixed assessed by the different 15N application methods averaged 86% in 1984 and 93% in 1985. In 1984, when white clover was predominant in the sward, 109 kg N/ha was fixed in 26 wk, compared to only 13.3 kg N/ha in the 22‐wk period of 1985 during which fescue dominated the sward. The yield‐independent estimates of percentage of clover N derived from N: fixation were more precise than the yield‐dependent values of total N2 fixed. In general, 15N applications made at the harvest preceding the N2‐ fixation measurement period gave similar percentages of N fixed in the 2 yr, compared to the higher values obtained from estimations based solely on residual 15N uptake. In all cases, however, estimations of total N2 fixed, in contrast to percentage N fixed, were not significantly influenced by method of 15N supply.
Field Plot Technique Comparison for Estimating Corn Grain and Dry Matter Yield
Authors: Wolkowski R. P. , Reisdorf T. A. , Bundy L. G.
Published: July 2010

Production recommendations are based on research data collected from small plots, with the assumption that experimental results are transferable to field‐scale conditions. Frequently, research techniques are selected to conserve resources and improve the efficiency of maintaining and harvesting the small‐plot experiments. This study evaluated the effects of plant density, plot length, alley size, and harvest method on corn (Zea mays L. ) grain and dry matter yield. Grain and dry matter yield decreased as harvested length increased. Alleys (0.75 or 3.0 m wide) increased grain yield relative to plots without alleys, but had no effect on dry matter yield. Combine‐harvested grain yields were equal to or higher than yields obtained by hand harvesting and stationary shelling due to lower grain losses during shelling with the combine. A sample size of 10 to 15 plants per plot minimized the coefficient of deviation of corn dry matter yield determination.
Conversion of Fertilized Annual Range Forage to Beef Cattle Liveweight Gain
Authors: Raguse C. A. , Taggard K. L. , Hull J. L. , Morris J. G. , George M. R. , Larsen L. C.
Published: July 2010

A 3‐yr field experiment evaluated average daily (ADG) and total seasonal (LG) weight gains of growing beef cattle (Bos taurus) on fertilized California foothill annual range. Soils were a mixture of four series of alfisols. Nitrogen was applied alone at 45 or 90 kg ha−1, P and S were applied together at 34P 37S or 67P 74S kg ha−1, and the two N rates were combined with 34P 37S. Two 13.2‐ha replications were stocked with 215‐kg steers in late November, and stocking rates were increased twice during a grazing season averaging 190 d. Forage on offer (FL) varied from 400 to 2500 kg ha−1. Annual forage production (FP) varied from 2500 to 5700 kg ha−1 and differed (P<0.05) between treatments and years. Year‐to‐year and within‐year variations in rainfall influenced FP. Average daily gains over the season varied linearly from less than 0.2 to over 1.0 kg steer−1. Differences in ADG due to treatments were largely restricted to the first year and to treatments with N, P, and S or the higher level of PS, but 3‐yr trends were not significant. Average daily gain was not strongly influenced by either FL or legume content of the forage. Three‐year LG was highest for the two NPS and the higher PS treatment. Fertilization increased forage organic matter digestibility and N concentrations over the control. Results indicate that either N, P, and S or a sufficient level of P and S to stimulate production of legume N was required for high forage production.
Proportionate Allocation of Pasture Subsamples for Laboratory Quality Analysis
Authors: Hill N. S. , Fales S. L. , Hoveland C. S.
Published: July 2010

Chemical analysis of pasture subsamples is an expensive and time consuming process. The objective of this project was to develop a method by which the number of pasture subsamples can be reduced for routing chemical analysis. Pasture sumsamples of pure alfalfa (Medicago sativa L.) or birdsfoot trefoil (Lotus corniculatus L.) were combined into proportionately allocated samples (PA). Laboratory analysis of in vitro dry matter disappearance (IVDMD) and crude protein (CP) were conducted on the subsamples and PA. Numerical averages (NA) and weighted means (WM) were calculated for IVDMD and CP of the subsamples. One subsample was randomly selected (RS) to estimate IVDMD and CP. The NA, PA, and RS were regressed with WM to determine the goodness of fit of the data for each method. Squared correaltion coefficients of the WM (dependent variable) and PA (independent variable) comparison were 0.99 and 0.93 for IVDMD and CP, respectively. The PA reduced sample number to one‐sixth of the original sample volume. The PA was an excellent method of reducing sample volume for IVDMD and CP analysis of pure samples of alfalfa and birdsfoot trefoil.
Cation Radius and pH of Drying Agent Solutions Influence on Alfalfa Drying Rates
Authors: Panciera M. T. , Walgenbach R. P. , Bula R. J.
Published: July 2010

Chemical drying agents based on K2CO3 reduce the drying time of alfalfa (Medicago sativa L.), but the effects of cation radius and solution pH on drying agent efficacy have not been defined. Studies were conducted to define the effects of sampling date, cation radius, and pH on alfalfa drying time and the drying process. Nine treatments and a distilled water control were applied to field grown ‘Spectrum’ alfalfa sampled on 5 June, 17 July, and 16 Aug. 1984. Treatments consisted of nine combinations of three cations (Na+, K+, Cs+) and three anions (C2H3O2=, CO3−, OH−). Cation radii were 0.097 to 0.167nm and pH ranged from 7.5 to 13.3. Samples were allowed to dry under ambient laboratory conditions. Water contents (WC, g water kg−1 dry matter) were determined at intervals and data were fitted to a biexponential curve. All chemicals reduced the drying time of alfalfa relative to controls, but K2CO3, KOH, Cs2CO3, and CsOH were the most effective compounds. Controls dried to a WC of 250 in 126 to 184 h, while treated forage dried to the same level in 32 to 110 h. A significant sampling date ✕ treatment interaction occurred for drying time and some of the shortest drying times were observed for the June sampling date. Cation radius and pH accounted for 73 to 90% of the variation in drying time among chemicals. Rapid phase drying accounted for loss of 394 to 538 g kg−1 of initial moisture for controls and 252 to 949 g kg−1 for chemical treatments. Increasing cation radius and pH increased the efficacy of drying agents under laboratory conditions.
Reduced Tillage System Influence on Yield of Sunflower Hybrids
Authors: Deibert Edward J.
Published: July 2010

Information on the effect of reduced tillage on sunflower (Helianthus annuus L.) production with different hybrids is limited. A 3‐yr study (1984 to 1986) was undertaken to evaluate the effect of tillage system and weed control method on seed weight, yield, oil concentration, and total oil of early and late maturity sunflower hybrids under dryland conditions in North Dakota. Sunflower hybrids were grown on a Fargo clay soil (fine, montmorillonitic, frigid Vertic Haplaquolls) with established long term tillage plots. Tillage treatments included conventional (Plow) and three reduced tillage systems (Sweep, Intertill, and No‐till) with weed control provided by herbicides with and without cultivation. Yield, weight, oil concentration, and oil yield of the sunflower seed was not significantly different among tillage systems or between weed control methods. Hybrids performed similarly in the seed parameters measured, although the late maturity hybrid consistently produced smaller seed. Results from the study indicated that early maturity sunflower hybrids are better adapted to the dryland areas of the cool northern states because seed yield and quality, irrespective of tillage or weed control method, were equal to or better than those for late maturity hybrids.
Johnsongrass Control in Conventionally Tilled and No‐Tilled Soybean with Foliar‐Applied Herbicides
Authors: Banks P. A. , Bundschuh S. A.
Published: July 2010

Perennial johnsongrass [Sorghum halepense (L.) Pers.] is costly and difficult to control in soybean [Glycine max (L.) Merr.]. Selective and nonselective foliar‐active herbicides were evaluated for activity and residual control of rhizome johnsongrass in conventional‐ and no‐till soybean culture. Broadcast foliar applications of selective graminacides and rope‐wick applications of nonselective foliar‐active herbicides were applied to rhizome johnsongrass growing in conventional‐till and no‐till soybean in 1984 and 1985. Selective graminacides generally provided excellent johnsongrass control (90 to 100%) that resulted in higher soybean yields than plots treated with rope‐wick applied herbicides. Selective graminacides also provided greater suppression of johnsongrass regrowth in the year following treatment compared with the nonselective herbicides. Two applications of selective graminacides did not improve johnsongrass control as compared with one application. Two rope‐wick applications of glyphosate [N‐(phosphonomethyl)glycine] or sulfosate (trimethylsulfoniumcarboxy methylaminomethylphosphonate) improved johnsongrass control, as compared with one application, in one of two years, but soybean yields did not always equal that applied with selective graminacides. Tillage did not significantly affect johnsongrass control with any of the treatments.
Evaluation of Soybean Zinc and Manganese Requirements by the M‐DRIS and Sufficiency Range Methods
Authors: Hallmark W. B. , Beverly R. B. , Parker M. B. , Adams J. F. , Boswell F. C. , Ohki K. , Shuman L. M. , Wilson D. O.
Published: July 2010

The modified‐diagnosis and recommendation integrated system (M‐DRIS) and sufficiency range method (SRM) have not been compared for accuracy of Zn and Mn diagnoses for soybean [Glycine max (L.) Merr.]. Consequently, M‐DRIS and SRM were evaluated for diagnosing Zn deficiencies for two site‐years in Alabama, and Mn deficiencies and sufficiencies for three site‐years in Georgia. The SRM was more accurate than M‐DRIS in detecting when Zn was deficient (P < 0.05) and when Mn was not deficient (P < 0.01). However, M‐DRIS and SRM did not differ (P > 0.10) where Mn was deficient. Partial regression analysis indicated that M‐DRIS also incorrectly diagnosed Ca as deficient in the Alabama studies. False M‐DRIS diagnoses of Mn and Ca deficiencies were attributed to their inflated concentration and ratio means in the M‐DRIS data base, which may also have contributed to false diagnoses of K, Mg, Cu, and Fe deficiencies in the Georgia study. Results demonstrate the danger of using inflated nutrient means in M‐DRIS diagnoses. Further work is needed to improve the diagnostic accuracy of M‐DRIS.
Composition and Yields of Alfalfa Fresh Forage, Field Cured Hay, and Pressed Forage
Authors: Collins Michael
Published: July 2010

A mechanical dewatering process was developed to avoid losses in yield and quality incurred during field hay curing. A 4‐yr field study was conducted to gain information on factors affecting hay curing losses and to compare hay to mechanically dewatered alfalfa (Medicago sativa L.). Ten harvest regimes were imposed on alfalfa monocultures to provide a wide range of fresh forage compositions and of hay curing conditions. Over the 4 yr, hay averaged 31.0 g kg−1 of N, 3.3 g kg−1 less than herbage, but 3.7 g kg−1 higher than pressed forage. Hay in vitro dry matter disappearance (IVDMD) was 596 g kg−1, 10% less than herbage, but similar to pressed forage at 589 g kg−1. Pressed forage was highest in neutral detergent fiber (NDF) at 559 g kg−1 while fresh forage had 422 g kg−1 and hay had 518 g kg−1. The best single predictors of hay concentrations of N, NDF, and IVDMD were fresh forage concentrations of the same constituents. Other significant variables for prediction of hay composition included dry matter loss (DML) during hay curing, rain amount, and hay curing time. Since hay curing and pressing both affected NDF concentration more than IVDMD, preservation system effects on intake potential could be even greater than effects on digestibility. The finding that fresh forage quality is the primary determinant of alfalfa hay quality indicates that close attention to quality at the time of cutting should more consistently produce hay of the desired quality than would delaying harvest in an attempt to avoid rain. The pressed forage and the protein concentrate together produce yields similar to or greater than those of hay and reduce N losses by nearly one‐half.
Establishiment of Kleingrass with Annual Ryegrass and Other Cultural Treatments
Authors: Bovey R. W. , Hauser V. L. , Meyer R. E.
Published: July 2010

Weed control is required after seeding kleingrass (Panicum coloratum L.) to assure successful stand establishment. Four field experiments were conducted over a 4‐yr period at two sites in Texas to evaluate a winter cover of annual ryegrass (Lolium multiflorum Lam.) and cultural treatments before seeding kleingrass as possible weed control methods. Hand‐weeding during establishment increased kleingrass forage production to 22 times that was produced in an unweeded control. Kleingrass was successfully established at one site by seeding into annual ryegrass stubble. The stand persisted for 3 yr with little maintenance. The beneficial effects of annual ryegrass cover during the winter before seeding kleingrass were not confirmed in all experiments. Kleingrass establishment following winter cover crops of arrowleaf clover (Trifolium vesiculosum Savi.) oat (Avena sativa L.) or weeds was poor. Conversely, a heavy cover of ryegrass kept the soil cool and was responsible for poor kleingrass germination and growth at one site. Kleingrass establishment was most successful when both ryegrass and weeds were removed by herbicides or by tillage before seeding.
Sugarbeet Yield and Quality in Relation to Residual Beef Feedlot Waste
Authors: Eck H. V. , Winter S. R. , Smith S. J.
Published: July 2010

Use of beef feedlot waste (FLW) in crop rotations including sugarbeets (Beta vulgaris L.) would provide a use for a surplus waste product. Objectives of this study were to assess the effects of FLW on soil chemical characteristics and on sugarbeet yield and quality. Amounts of FLW applied on Pullman clay loam (fine, mixed. thermic Torrertic Palleustoll) over a 16‐yr period ranged from 0 to 1608 Mg ha−1. Retention (of applied FLW drymatter (DM) as soil OM ranged from 14 to 2%, N (applied in DM) as total N from 47 to 5%, and P as NaHCO3‐extractable P from 18 to 8%. Retention depended on amount and recency of application. Nitrifiable N, determined chemically, was closely associated with OM (r = 0.88), total N (r = 0.93), and with NO−3‐N (r = 0.95). All treatments that had previously received FLW produced significantly higher sugarbeet root and sucrose yields than those that had received N, P, and K plus added N on the sugarbeet crop. Consequently, use of FLW in crop rotations including sugarbeets merits further study. Sucrose concentrations 'of the sugarbeets were inversely related while concentrations of Na, NO3, and amino‐N in the roots were directly related to soil NO−3‐N and inversely related to sucrose. Nitrifiable N was closely associated with root yield, sucrose yield, sucrose concentration, nitrate grade, and amino‐N. Nitrifiable N, as determined in this study, deserves further evaluation as an indicator of N supplying capacity of the soil.
Late‐Winter No‐Till Seeding of Alfalfa into Autumn‐Suppressed Tall Fescue
Authors: Zarnstorff M. E. , Chamblee D. S. , Mueller J. P. , Campbell W. V.
Published: July 2010

Alfalfa (Medicago sativa L.) has traditionally been established in the autumn in the southeastern USA, even though insects, disease, and/or moisture supply may limit successful conventional or notillage establishment. In previous studies, late‐winter (February or March) no‐till seedings failed because chemicals applied at time of seeding failed to suppress the grass. The objective of this study was to evaluate autumn chemical suppression and/or killing of tall fescue (Festuca arundinacea Schreb. ‘Kentucky 31’), late‐winter seeding date (February or March), and weed control in the seeding year on no‐till establishment of ‘Cimarron’ alfalfa into a tall fescue dominant sward. Three, 2‐yr field experiments were conducted during 1985 to 1987 on Typic Hapludult soils. Common to all experiments was a 23 factorial arrangement of treatments consisting of; (i) two late‐winter seeding dates of alfalfa, mid‐February or mid‐March, (ii) autumn applied paraquat (1‐1′‐dimethyl‐4,4′‐bipyridinium ion) at 0.28 kg ha−1 a.i. or glyphosate [N‐(phosphonomethyl) glycine] at 2.24 kg ha−1 a.i. for grass suppression, and (iii) the use of no weed control in the seeding year vs. weed control during the seeding year. A no‐grass suppression treatment was included for each seeding date. Insect grazing damaged 15% of the alfalfa seedlings, with an average damage per plant of 4%. Autumn grass suppression followed by late‐winter (February or March) no‐till seeding of alfalfa resulted in alfalfa yields of 6.77 Mg ha−1 as compared to no‐grass suppression yields of 3.27 Mg ha−1 for the seeding year. Weed control in the seeding year increased alfalfa yields in the March seeding 2.51 Mg ha−1 as compared to no‐weed control in the seeding year. We conclude that late‐winter (February or March) no‐till seeding alfalfa into a cool‐season perennial grass sward in the southeast region of the USA is an excellent alternative to autumn providing the grass is killed in the autumn prior to seeding.
Programming Techniques to Expedite Communication of Scientific Models
Authors: Waldman Sue E. , Rickman Ron W.
Published: July 2010

Computer programs describing scientific models aid in communicating models and their multiple components to other scientists. If several language‐independent programming practices are used, programs can be much more valuable communication tools than are many of the currently distributed programs. Text file input of parameter values and prompts permit simple modification of program algorithms and screen instructions without requiring recompiling. Standardization of variable name lengths to the lowest common denominator (which seems to be FORTRAN 77) of six characters increase the portability of code. Structured programming, subroutines, absolute abstinence from the use of GO TOs, and appropriate documentation provide organized, decipherable code and hence readable and usable programs. Language dependent practices of modular programming and passing of variables can simplify major model changes and program redesign. Programs written as communication tools do not necessarily execute in minimum time but can dramatically reduce time needed to understand a model and incorporate its code, without introducing error, into the code of larger models or simulations.
Cocklebur and Velvetleaf Interference with Soybean Grown at Different Densities and Planting Patterns
Authors: Marwat Khan Bahadar , Nafziger Emerson D.
Published: July 2010

Two common problems in soybean [Glycine max (L.) Merr.] fields are weeds and incomplete crop plant stands, and these problems may interact in their influence on soybean yield. A study was conducted in 1986 and 1987 to examine whether weed interference was influenced by soybean plant stand and planting pattern. In full stands (26 plants/m row) of soybean, common cocklebur (Xanthium strumarium L.) and velvetleaf (Abutilon theophrasti Medic.) spaced 1.5 m apart in the row decreased soybean yields 29 and 34%, respectively, in 1986 and 19 and 15%, respectively, in 1987. Decreasing the soybean stand 20, 40, and 60% without weeds resulted in yield losses of 8, 18, and 34% (across both years) in evenly spaced soybean plants, while similar stand losses caused by removal of sections of row resulted in yield losses of 14, 28, and 35%, across both years, respectively. When common cocklebur and velvetleaf were present, percentage yield decreases due to stand losses were similar to those in the weedfree treatment; there was no interaction between weed treatment and stand loss treatments. Light interception by the canopy, measured only in 1987, was higher in weedy plots than in weedfree plots, with the additional interception presumably due to the weeds. Common cocklebur produced more dry weight than did velvetleaf, but the two weeds had similar effects on soybean yield. These results indicate that, while weed competition and stand loss can both cause substantial yield losses in soybean, the effect of these factors is additive when both occur in the same field, and weed growth is not greatly enhanced by decreased competition resulting from loss of soybean stand.
Pepper Seedling Response to Steady and Transient Nitrogen and Phosphorus Supply
Authors: Bar‐Tal A. , Bar‐Yosef B. , Kafkafi U.
Published: July 2010

Using transplants for growing pepper (Capsicum annuum L.) is widespread, but little is known about seedling response to transient N and P supply during tbe nursery growth stage. The objective of this work was to study the effect of steady and alternating N and P concentrations in solution culture on pepper seedling development, dry‐matter production rate, and N and P uptake rates, to allow better control of production by transplants. Seedlings were grown in trays of pyramidal cells, packed with vermiculite and floated on well‐aerated nutrient solutions of high (6 mM) or low (1 mM) N and high (0.25 mM) or low (0.01 or 0.03 mM) P. Dry‐matter accumulation in seedling tops as a function of time conformed in all treatments to a first‐order exponential equation. The growth rate constant was significantly higher in the high than in the low N or P concentrations. Root growth rate was less affected by the N and P solution concentration than was the top growth rate. Five‐day‐long alternations of solution concentration from high to low and from low to high N and P significantly changed dry‐matter production rate and nutrient content in plants. Growth and uptake rates regained their original values when seedlings were re‐exposed for 5 d to the original solutions. The rapid changes in growth rate were attributed to rapid variations in the flux of N and P uptake in response to changes in solution concentrations, which affected N and P concentration in plant organs. Varying N and P concentrations in tops affected dry‐matter production rate, whereas variations in N and P concentrations in roots influenced the flux of uptake of P and N, respectively.
Subclover Early Growth Responses to Levels and Placements of Superphosphate and Ammonium Nitrate
Authors: Frost W. E. , Raguse C. A. , Taggard K. L.
Published: July 2010

Single superphosophate (SSP) commonly has been used to correct soil deficiencies of P and S in rangeland seedings of annual legumes. This study evaluated rates and soil placement of P and S as SSP and N as ammonium nitrate on germination (emergence), seedling growth, and nodulation of subterranean clover (Trifolium subterraneum L.). The soil was a Sobrante‐Las Posas association (fineloamy or fine mixed thermic family of mollic haploxeralfs). Plants were grown from seed in three separate greenhouse experiments. The SSP levels varied from 31 to 4000 kg ha−1 (equivalent to 2.4 and 313 kg ha−1 P and 3.7 and 480 kg ha−1 S). Nitrogen varied from 40 to 160 kg ha−1. Placements were: 5 cm below the seed, 1.25 cm side‐banded, broadcast, and seed placed. Responses measured included emergence, growth rate, shoot weight, nodulation, and P toxicity symptoms. Negative effects of SSP mainly reduced emergence and increased plant toxicity symptoms and occurred at levels ≥1000 to 4000 kg ha−1. Negative effects of N (at 160 kg ha−1) were mainly on nodulation. Positive effects on most growth parameters and nodulation were largely confined to SSP levels ≤500 kg ha−1 and were best expressed by an asymptotic regression function. Placement effects generally were small except for seed‐placed reduction of emergence above 1000 kg ha−1 SSP. Soil‐banded placement treatments usually were more beneficial to growth than either broadcast or seed placed.
Genotype and Topping Stage in Relation to Maturity in Burley Tobacco
Authors: Kelley W. T. , Bowman D. T.
Published: July 2010

The danger of frost damage on burley tobacco (Nicotiana tabacum L.) is an ever present risk to growers in western North Carolina. Therefore, a study was initiated to investigate the effects of topping stage and use of early and late‐flowering genotypes on maturity. Four genotypes (‘TN 86’, ‘VA 509’, m.s. Burley 21 ✕ L8, and ‘m.s. Ky 14 ✕ L8’) and three topping stages (early button, elongated button, and full flower) were examined at two locations (Laurel Springs and Waynesville, NC) in 1986 and 1987. Maturity was assessed by visually examining color of the tenth leaf from the bottom of the plant using a scale which is highly correlated with relative concentrations of chlorophylls and carotenoids and is based on the Munsell Color Charts for Plant Tissues. Data on color at harvest were analyzed. Late‐flowering cultivars, TN 86 and VA 509, were found to be paler in color at harvest. The paler color at harvest of the cultivars did not always translate into better quality tobacco in the cured leaf state. Choice of cultivar for short‐season environments should not necessarily be based on flowering date but on final quality of the cured leaf based on data collected over several seasons.
Barley Treated with Ethephon: I. Yield Components and Net Grain Yield
Authors: Moes J. , Stobbe E. H.
Published: July 2010

Ethephon [(2‐chloroethyl)phosphonic acid] effectively reduces lodging in barley (Hordeum vulgare L.), but also may have positive or negative influences on grain yield and yield components even if lodging does not occur. The objective of this study was to investigate the effects of ethephon on yield and yield components of barley under western Canadian conditions. In 1987, 1988, and 1989 at Winnipeg MB, ‘Argyle’ conventional height and ‘Samson’ semidwarf barley were grown at 100 and 300 plants m−2 and treated with ethephon at Zadoks growth stage 35 or 45. At harvest, grain yield samples were taken by hand or by combine, and yield components were determined. When lodging occurred, Belgian lodging indices were determined. The two cultivars responded similarly to ethephon application. Hand‐harvested grain yields were either unaffected or reduced by ethephon, but combine‐harvested yield tended to be increased by ethephon in 1989 when lodging was severe in untreated plots. Reductions in hand‐harvested grain yield of ethephon‐treated plots were primarily due to reductions in kernels per spike, which occurred in all 3 yr for barley grown at both plant densities. Ethephon increased spikes per plant for barley grown at both 100 and 300 plants m−2 in 1987, which at the low plant density compensated for reductions in kernels per spike and kernel mass. Barley in ethephon‐treated plots tended to be delayed in maturity compared with untreated plots. This was particularly true in 1987 and 1989, when late tiller emergence was promoted to the greatest extent by ethephon when moisture conditions were favorable. The potential for ethephon to cause yield reductions restricts the use of ethephon in western Canada to situations where the risk of severe lodging is high.
Sugarbeet Response to Subsoiling and Wheel Traffic
Authors: Johnson B. S. , Erickson A. E.
Published: July 2010

Normal tillage practices often create poor physical conditions for crop growth on lake plain soils in Michigan. Tillage studies were conducted in 1983 on Parkhill loam (fine‐loamy, mixed, nonacidic, mesic Mollic Haplaquept) and from 1983 to 1985 on Charity clay (fine, illitic (calcareous), mesic Aerie Haplaquept) to evaluate the potential for increasing sugarbeet (Beta vulgaris L.) yield by reducing the physical limitations of these soils. Treatments consisted of eight combinations of a primary tillage and secondary tillage variable. Primary tillage was applied in the fall and consisted of subsoiling and moldboard plowing (SMP), subsoiling and shallow chiseling (SCH), moldboard plowing (MP), or shallow chiseling (CH). The secondary tillage vairable consisted of the presence or absence of tractor wheel traffic occurring during seedbed preparation. Response of sugarbeet ‘US‐H20’ and ‘US‐H23’ was evident each year and was attributed in part to improved soil aeration where subsoiling was performed and where wheel traffic was absent. Response was greatest in 1983 when subsoiling increased root yield of US‐H20 by 10.7 Mg ha−1 on Parkhill loam and by 7.6 Mg ha−1 on Charity clay. Elimination of preplant wheel traffic increased root yields by an average of 8.3 Mg ha−1 on Charity clay that year. Recoverable sucrose yield was affected in proportion to root yield each year because tillage had no effect on recoverable sucrose concentration. The need to minimize wheel traffic in sugarbeet production systems, regardless of the primary tillage practices employed, was evidenced by results of this study.
Stimulation of Alfalfa Bud and Shoot Development with Cytokinins
Authors: Tomkins J. P. , Hall M. H.
Published: July 2010

As the number of alfalfa (Medicago sativa L.) plants in a stand declines, a compensatory increase in number of shoots per plant maintains production; however, when plant density declines below a critical level, compensatory shoot production is insufficient to maintain yield. Stimulating new shoots to grow in low density alfalfa stands may allow for continued economic alfalfa production in low density stands. Cytokinins have increased shoot growth in other plants. Our objective was to determine the effect of cytokinin on alfalfa development, yield, and quality. Two cytokinins, kinetin (6‐furfurylaminopurine) and BAP (6‐benzylaminopurine), were applied foliarly at several concentrations to alfalfa grown at different densities in both a greenhouse and field environment. Cytokinins increased shoots per plant, shoot length, and leaf area per plant. Increases in these plant characteristics were positively correlated (r > 0.74) with increased yield per plant. Average herbage dry matter (DM) yields per plant were increased by 35% in the greenhouse study and 79% in the field study, by application of cytokinins. The stimulatory effects of cytokinin were similar between low and high plant density stands. In the greenhouse study, delaying cytokinin application from immediately after harvest until 3 or 7 d after harvest reduced the yield per plant by 9 or 15%, respectively. Alfalfa quality was unaffected in the field and reduced in the greenhouse (average of 13 g kg−1 less crude protein and 29 g kg−1 more acid detergent fiber) by cytokinin application. Cytokinin application to alfalfa stubble increases the number of shoots and DM yield per plant and may prove to be a method of increasing or maintaining yield under field production situations.
Speedometer for Operator‐Propelled Equipment
Authors: Wolf D. D. , Wolf L. D. , Parrish D. J.
Published: July 2010

Accurate delivery of solutions from a sprayer or of seed and fertilizer from ground‐driven spinner spreaders requires accurate travel speeds. The objective of this note is to provide plans for building your own inexpensive electronic speedometer. Where the applicator is mounted on wheels, an accurate speed can be maintained using a computerized bicycle speed indicator and small magnets secured at equal intervals around the spokes. Insulated wire connects the magnetic sensor to a computerized digital display unit mounted within view of the operator. The computerized display is calibrated for the diameter of the wheel by settings in the operator's manual. The indicated speed is 10 times the actual speed. Speed is updated each second and displayed to the nearest 0.1 km h−1. The computer unit and materials can be purchased from local suppliers and assembled in a few hours. Evaluation of performance was made by four subjects under several conditions. When considering subjects and conditions, the standard error of travel speed was 0.056 km h−1 when operating the unit at a target of 3.22 km h−1 (2.0 MPH). This means that a range of 3.16 to 3.28 km h−1 could be achieved 95% of the time while intending to travel at 3.22 km h−1.
Sweet Corn Genotypes versus Ethephon in Relation to Yield Components
Authors: Fritz V. A. , Hebel J. B. , Borowski A. M.
Published: July 2010

One of the major production related problems associated with sweet corn (Zea mays L. var. rugosa and particularly in the sh2 cultivars, has been root lodging. A study was thus conducted to determine if foliarly applied ethephon [(2‐chloroethyl) phosphonic acid] would effectively reduce susceptibility to root lodging in sweet corn, and to characterize three sweet corn genotypes' responses to ethephon. In 1987 and 1988 the effects of ethephon treatments on plant height, root lodging, and yield were evaluated using three sweet corn genotypes, sugary (su), sugary enhanced (se), and shrunken (sh2). Three cultivars were used within each genotype: Commander, Jubilee, and Stylepak (su); Sentry, Miracle, and Tendertreat (se); and Crisp n Sweet 710, Summer Sweet 8000, and Sweetie (sh2. Ethephon was applied foliarly at 280 g ha−1 at one of two stages of embryonic tassel growth (2.5 ‐ 5.0 or 15.0 ‐ 23.0 cm in length) to each of the sweet corn genotypes and cultivars. Ethephon reduced plant height in both years by 4 to 26%. Root lodging was significantly reduced in Miracle and Tendertreat (se) in 1987 in plants treated with ethephon. Yields were reduced and maturity was delayed in Sentry (se) and Sweetie (sh2) when treated with ethephon. The use of ethephon may be beneficial in cultivars that have a high tendency to lodge. However, during hot, dry years (i.e., 1988), it may be advisable to forego ethephon application on some cultivars.
Microcomputer‐Based Experiment Management System: I. Randomization, Label Printing, and Experiment Support
Authors: Loussaert Dale
Published: July 2010

An experiment management system is described that will aid in the execution of many types of biological experimentation. Menu driven software written for the IBM/compatible microcomputer will aid in pseudo‐random assignment of a number of treatment and experimental designs. The software will print labels and data collection sheets and facilitate asynchronous data transfer from the portable computers to the IBM/compatible computer. Data may be transformed and interline and intraline data field checking done. Data fields of different data files may be merged by experimental unit number and the experimental descriptor information, stored in a reference file during randomization, may be merged with the corresponding data of each experimental unit. The merged data and experimental unit descriptor information is output in a format suitable for analysis by the analysis software of this series, in a format suitable for analysis by SAS or in a general format compatible with spreadsheet or data base programs.
Agronomic Characteristics That Identify High Yield, High Protein Soybean Genotypes
Authors: Imsande John
Published: July 2010

Seed yield and seed protein content are both heritable traits; however, breeding trials frequently reveal a negative correlation between the two traits. The objectives of this study were to measure and calculate various N‐dependent growth characteristics of soybean [Glycine max (L.) Merr.] and to determine their relation to seed yield and seed protein. Well‐nodulated plants, each fixing approximately 180 mg N during pod fill, were grown hydroponically in a growth chamber with or without NO3−N during pod filling. Twenty growth‐yield characteristics, including yield, harvest index, N harvest index, and Kjeldahl analysis of N2 fixation, were measured or calculated for each of the 384 plants examined. The highest seed yields, approximately 10 g plant−1, and the highest seed N contents, approximately 560 mg plant−1, were obtained when well‐nodulated plants were provided some fertilizer‐N during pod fill. Except for N content (%) of the dried plant, correlations between each pair of the 20 N‐dependent growth‐yield characteristics were generally positive. In the absence of fertilizer‐N during pod fill, however, N content (%) of the seeds did not correlate with either harvest index or N harvest index, suggesting that insufficient N during pod fill interferes with the orderly mobilization of foliar‐N to the developing seeds. New physiological parameters (seed yield merit, N yield merit, and merit of genotype) are proposed for the identification of genetic lines that produce both a high seed yield and a high seed protein content.
Uptake of Calcium and Magnesium by Cotton Grown under Dryland Conditions
Authors: Mullins G. L. , Burmester C. H.
Published: July 2010

The mid‐1940s was the last time an intensive study of the Ca and Mg nutrition of cotton (Gossypium hirsutum L.) was conducted in the USA. Since that time cultivars and cultural practices have changed, thus, field studies were conducted for 2 yr to evaluate the Ca and Mg uptake characteristics of four cultivars that are representative of those now produced in the South: ‘Deltapine 90’, ‘Stoneville 825’, ‘Coker315’ and ‘Paymaster 145’. They were grown on a nonirrigated Decatur silt loam (clayey, thermic, kaolinitic, Rhodic Paleudults) and a nonirrigated Norfolk fine sandy loam (fine loamy, thermic, siliceous, Typic Paleudults) in Alabama. Plants were collected at 2‐wk intervals throughout the growing season, beginning at 15 d after emergence, partitioned into leaves, stems, burs, seed, and lint, and analyzed (except for lint) for Ca and Mg. Total Ca and Mg uptake when averaged for both soils and all four cultivars was 64 and 18 kg ha−1, respectively (or 9.3 kg of Ca and 2.6 kg Mg per 100 kg lint produced). Total Ca uptake was significantly lower on the Norfolk soil (44 kg ha−1) as compared to the Decatur soil (75 kg ha−1) which had a higher level of extractable Ca. There were no cultivar differences in total Ca and Mg uptake or uptake within a given plant part. There were no consistent differences among the cultivars for the concentration of Ca in the various plant parts. The concentration of Mg in the leaves and burs was affected by the cultivar. These cultivars accumulated similar amounts of Ca and Mg as compared to older cultivars, although previous research has shown that modern cultivars partition dry matter differently from older cultivars.
Continuous Position and Speed Sensor for Center Pivot Sprinkler Systems
Authors: Thomson Steven J. , Smith Matt C.
Published: July 2010

Determination of center pivot position and speed are frequently required for both research and commercial operations. To represent these variables accurately, a simple device that provides a continuous, high‐resolution representation of center pivot position and speed was constructed of readily available parts. A goal was to develop a device that was an improvement from previous designs. A timing belt was bonded to a center pivot riser, and as the riser turned, the belt meshed with a gear causing it to rotate a 360 ° potentiometer. The device described can be interfaced to a computer at a central location to record center pivot position and calculate rotational speed. Measured position had a coefficient of variation of 1.7% for five trials. The sensor can improve water and chemical management for both research and commercial center pivot irrigation.