bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uptake of Calcium and Magnesium by Cotton Grown under Dryland Conditions
Authors: Mullins G. L. , Burmester C. H. 
Published: July 2010

AbstractThe 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

AbstractDetermination 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.
Computer Controlled Chemical Field Applicator for Research
Authors: Loussaert Dale 
Published: July 2010

AbstractAn automated, computer controlled sprayer was developed that interfaces experiment management with chemical application. Treatment combinations of a randomly assigned experiment can be assigned sprayer boom numbers using an IBM‐XT (compatible) computer. The sprayer boom number associated with each experimental unit is transferred to a portable computer and used as a template for sprayer control. Subsets of the information can be arranged in any order desired. As the sprayer moves across the experimental plots the computer activates the appropriate boom associated with the treatment combination assigned to each plot. The portable computer will control the sprayer in three modes: manual (the user switches the sprayer on and off between plots); semi automatic (the user starts each plot but the computer turns the booms off at the end of the plots); and automatic (the user marks the start of the first plot and the computer turns on and off each remaining plot). This system expands the utility of multi‐boom research field sprayers.
Plot Sprinklers for Irrigation Research
Authors: Eldredge E. P. , Shock C. C. , Stieber T. D. 
Published: July 2010

AbstractPortable plot sprinklers were developed that allowed individual plots to be irrigated independently of other plots. Each plot sprinkler consisted of three rotary‐pendulum, square‐pattern sprinkler heads mounted on a PVC pipe frame. Plot sprinkler water output was 0.9 m3 h−l, on an area 4.6 m wide by 13.7 m long, with Cu = 80%, when operated at 86 kPa. Plot sprinklers were used to apply irrigation treatments In a randomized block design to evaluate potato (Solanum tuberosum L. ‘Russet Burbank’) tuber quality response to six levels of transitory drought stress during early tuber bulking. Yield of U.S. Number One tubers decreased and yield of U.S. Number Two tubers increased with increasing severity of transitory drought stress. Plot sprinklers allow irrigation of plots in an experiment at different frequencies or durations.
Adjustable Soil Coring Machine for Sampling in Tall Row Crops
Authors: Hatfield J. L. , Schaaf S. L. 
Published: July 2010

AbstractSoil sampling is difficult when the crop canopy is tall and row width is variable between experiments. A specialized hydraulically‐driven soil sampling tractor was designed and constructed with variable wheel width and clearance height. The tractor has an adjustable wheel width from 1.6 (5.2) to 2.4 m (7.9 ft.) and clearance height from 2.2 (7.2) to 2.7 m (8.9 ft.). A Giddings hydraulic soil coring probe is front mounted on the tractor. The operator can control wheel width, height, position of the operator platform and probe, travel direction, and speed from the console. Soil cores are carried on the tractor between sampling locations. The tractor mounted system has performed well during sampling trips throughout the growing season in various row widths.
A Hydraulic Soil Sampler Providing Minimum Field Plot Disruption
Authors: Baarstad L. L. , Rickman R. W. , Wilkins D. , Morita S. 
Published: July 2010

AbstractHydraulic‐powered soil samplers speed and simplify the collection of soil cores and plant root samples. Unfortunately, the vehicle carrying a sampler often damages a large area of the crop surrounding a sampling site and compacts the soH surface. The extent of such damage often prevents the use of powdered samplers. An attachment linking a Giddings1 hydraulic probe to a knuckle boom mounted on a 3‐t truck permitted removing soil cores from small field plots with virtually no damage to the crop or soil at the sample site (except for foot traffic). The objectives of this note are to describe and illustrate the attachment and present some examples of rapid, easy collection of soil cores that it provided. The hydraulic probe, when mounted at the end of a knuckle boom, was not restricted in any of its operations.
Water Table Gradient Effects on the Performance of Diverse Cowpea Cultivars
Authors: Timsina J. , Garrity D. P. , Pandey R. K. 
Published: July 2010

AbstractCowpea sown in tropical monsoon climates is often constrained by soil saturation and a high water table during growth. We hypothesized that a strong interaction exists between cowpea maturity class and the soil water table depth regime experienced during the growing season, and that the occurrence of shallow water table depths in the dry‐wet transition period before rice and the rapid decline in water table depth in the wet‐dry post‐rice period favor early maturing cultivars. The effects of three water table regimes on the performance of 24 diverse cowpea [Vigna unguiculat (L.) Walp] cultivars was studied on a Typic Tropudalf toposequence. The water table depths in the shallow (SWT), medium (MWT), and deep (DWT) water table regimes varied between 0.06 to 0.54 m, 0.28 to 0.96 m, and 0.68 to 1.44 m in the 2 yr of dry season (DS) experiments. In the wet season (WS), the three regimes were 0 to 0.27 m, 0.30 to 0.60 m, and 0.55 to 1.05 m. Most of the early maturing cultivars exhibited their best performance in the DWT regime, but the medium maturing cultivars were superior in seed yields in all water table regimes. The mean yields of the early maturing cultivars were reduced by 49% (1986–1987 DS) and 57% (1987–1988 DS) in SWT compared to DWT. They were reduced by 50% in the 1987 wet season. The mean yield reductions for the medium maturing cultivars were 40%, 54%, and 51%, respectively, in SWT compared to DWT. Pods per plant was the yield component most affected by excess moisture. Flowering in the SWT was delayed by 4 vs 5 d (DS) and 5 vs 7 d (WS) between the early and medium maturing cultivar groups, respectively. The superiority of the medium maturing cultivars was consistent among sites with a water table within the root zone for a major portion of the crop season.
Evapotranspiration and Yield of Beans as Affected by Mulch and Irrigation
Authors: Barros L. C. G. , Hanks R. J. 
Published: July 2010

AbstractMulch (crop residue) has been reported to increase soil water storage and crop yield, and to reduce soil water stress under some conditions. However, few studies have had irrigation, and thus evapotranspiration (ET), as a variable where soil water was controlled. Therefore, a study was conducted to evaluate the effect of mulch on ET, bean yield (Phaseolus vulgaris L.), and water use efficiency (WUE), under a wide range of irrigation levels. Treatments were two cultivars (Viva‐Pink and Red‐63), two mulch rates (bare, and 7.0 Mg ha−1 of wheat straw), and six irrigation levels (from 0.0 to 288 mm) for 2 yr. Different irrigation levels were achieved by a line source sprinkler. Evapotranspiration was estimated from measurements of irrigation, precipitation, soil water depletion, and estimated drainage. Transpiration (Tr) was estimated from a function of relative yield and relative ET. Dry matter and seed yields were significantly greater for mulched than for bare plots. Mulched plots had a higher WUE (yield/ET) than did bare plots for a given irrigation level but increased as irrigation level increased. Seasonal differences in ET between bare and mulched plots were small. The yield‐ET relation for mulch was linear but was distinctly different from bare soil, indicating a different partitioning of ET into soil water evaporation (Es) and Tr. For the conditions of this experiment, mulch reduced Es by about 45 mm, at the same ET, and Tr was increased by 45 mm. However, for tbe same irrigation level, ET was lower for mulched than for bare plots, indicating that not all of the water saved went to Tr.
Sources of Variation in the Spectrophotometric Assay of Hydrocyanic Acid Potential in Sorghum Seedlings
Authors: Lee R. D. , Johnson B. E. , Pedersen J. F. , Haskins F. A. , Gorz H. J. 
Published: July 2010

AbstractSpectrophotometry is a useful assay for hydrocyanic acid potential (HCN‐p) in sorghum and sudangrass [both Sorghum bicolor (L.) Moench] seedlings, but no systematic study of sources of variation in the procedure has been reported. Selfed seed was harvested from each of 12 ramets (two each from two sister plants from three low‐HCN‐p sudangrass parents), and seedlings for sampling were grown in a growth chamber, in two rows from each ramet. Seven‐day‐old seedlings were harvested and divided into two samples per row for extraction; two aliquots per extract were assayed spectrophotometrically for HCN‐p. The experiment was replicated three times. The three parents differed in HCN‐p. Rows within ramets, and samples within rows, were also significant sources of variation, but the magnitude of variance component estimates was small relative to that of the parents. Sister plants within parents, ramets within plants, and aliquots within samples were not significant sources of variation.
Using the Williams Equation to Evaluate Nutrient Uptake Rate by Intact Plants
Authors: Silberbush Moshe , Gbur Edward E. 
Published: July 2010

AbstractThe Williams equation uses root growth and nutrient accumulation data to evaluate nutrient uptake by plants. Accuracy of this equation depends on basic assumptions of constant uptake rate with time and space. The validity of the Williams equation and the assumptions underlying it were tested with sorghum [Sorghum bicolor (L.) Moench] plants grown in solution culture and analyzed for N, P, K, Ca, and Mg uptake. Only N and Ca influx were independent of time, as required by the equation. Influx of P, K, and Mg decreased linearly during the entire growth period. Mean root radius, which is assumed constant, decreased linearly with time. Consequently, a cautious and selective use of the equation is recommended.
Growth, Seed Yield, and Oil Content of Canola Grown under Saline Conditions
Authors: Francois Leland E. 
Published: July 2010

AbstractDue to health concerns regarding saturated fat in the human diet, canola (Brassica spp.) is becoming an increasingly important source of edible vegetable oil because of its low saturated fat content. This increased demand, and the need for crop diversification, will undoubtedly promote increased acreage of canola in the western USA, where some soils are or have the potential to become saline. Salt tolerance in two canola species (B. napus L. cv. Westar and B. campestris L. cv. Tobin) was determined in a 2‐yr field plot study. Six salinity treatments were imposed on a Holtville silty clay (clayey over loamy, montmorillonitic [calcareous], hyperthermic Typic Torrifluvent) by irrigating with waters salinized with NaCl and CaCl2 (1:1 w/w). Electrical conductivities of the irrigation waters ranged from 1.2 to 9.7 dS m−1 the first year, and 1.2 to 11.5 dS m−1 the second year. Seed yield, vegetative growth, oil content, and protein content in the oil‐free seed meal were measured. Relative seed yields of Westar and Tobin were unaffected by soil NaCl and CaCl2 (1:1 w/w) 9.7 dS m−1 (electrical conductivity of the saturated soil extract: ECe), respectively. Each unit increase in salinity above the thresholds reduced the seed yield of Westar by 13.0% and Tobin by 14.3%. These results place both canola species in the salt‐tolerant category. Increased salinity did not significantly affect the oil or protein content of the oil‐free seed meal. Vegetative growth of both species was unaffected by soil salinity up to 10.0 dS m−1 and the growth decline above this threshold was 11.2% per unit increase in salinity.
Variability among Soybean Genotypes in Response to Nodulation by a Rhizobitoxine‐Producing Strain of Bradyrhizobia
Authors: Fuhrmann Jeffry J. , Vasilas Bruce L. 
Published: July 2010

AbstractNodulation by rhizobitoxine‐producing (RT+) strains of Bradyrhizobium elkanii (syn. Bradyrhizobium japonicum; DNA homology group II) has been shown to reduce shoot growth, N2 fixation, and seed yield of ‘Forrest’ soybean (Glycine max [L.] Merr.). We conducted greenhouse and field experiments to assess the frequency of these negative responses among selected soybean cultivars. In the greenhouse, 38 cultivars representing a range of yield potentials, maturity groups, and growth habits were inoculated with B. elkanii strain USDA 94 (RT+) or B. japonicum strain USDA 110 (RT−). Large differences in tolerance to nodulation by RT+ bradyrhizobia were noted, as estimated visually and by comparing shoot weights (40 d after planting) of plants inoculated with the two strains. For the field study, two tolerant (Stafford and SS FFR 565), two moderately sensitive (Pharaoh and Williams 82), and two highly sensitive cultivars (Forrest and Hutcheson) were chosen. Seeds sown to vermiculite under greenhouse conditions were inoculated with either USDA 94 or a suspension of soil taken from the study site containing the indigenous bradyrhizobia. After 23 d, the nodulated seedlings were transplanted to 1.8‐m2 field microplots. Shoots were harvested at the R7 growth stage and analyzed for various response parameters. Only Forrest, Hutcheson, and Pharaoh were significantly affected by inoculation with USDA 94, which decreased seed yield, pod number, vegetative growth, and the amount of N2 fixed. These results support the hypothesis that significant genotypic variability exists in the response of soybeans to nodulation by RT+ bradyrhizobia. The greenhouse screening procedure can provide useful predictions of the field response of tolerant and highly sensitive cultivars, but may not be accurate for moderately sensitive cultivars.
Small‐Grain Precision Planter for Dryland Experimental Plots
Authors: Botha A. H. , Purchase J. L. , Wilkins D. E. 
Published: July 2010

AbstractSmall‐grain stand establishment in research plots of the summer rainfall region of South Africa is a problem because of dry surface soil. A vacuum system plot planter was developed to meet these requirements. The planter has simple adjustments for changes in species, cultivars, seeding rate, row spacing, and fertilizer rate. The precision planter has fertilizer tines and modified planter units. Uniform stands are achieved with most species at seeding rates varying from 5 to 100 kg ha−1 (4.5–89.0 lb acre−11), with no restriction in plot length. The unit is easily transported and can plant in excess of 80 5‐m (16.5 ft) plots h−11.
Supplemental Boron, Boll Retention Percentage, Ovary Carbohydrates, and Lint Yield in Modern Cotton Genotypes
Authors: Heitholt James J. 
Published: July 2010

AbstractCotton (Gossypium hirsutum L.) is sometimes grown on soils with low B concentration. However, most of the literature regarding the effects of supplemental B on cotton was obtained from obsolete, low‐yielding genotypes rather than modern, high‐yielding genotypes. Therefore, the objective of this study was to determine the effects of soil‐ and foliarapplied B on leaf blade B concentration, boll retention, and lint yield of modern cotton genotypes. In 1991, three genotypes (DES 119, DES 24‐8 ne normal leaf, and DES 24‐8 ne okra leaf) and in 1992, two genotypes (Deltapine 20 and Deltapine 5415) of cotton were grown in the field on a Beulah fine sandy loam (coarse‐loamy, mixed, thermic Typic Dystrochrepts) having 0.11 mg kg−1 hot water extractable B concentration. Treatments included preplant soil and foliar (first flower to end of bloom) B (78% Na2B8O13·4H2O, 20% Na2B4O7·5H2O) applications for seasonal totals of 0, 0.89, or 1.78 (1992 only) kg B ha−1. The lowest rate of foliar‐applied B increased leaf blade B concentration from 25 to 70 mg kg−1 in 1991 and from 54 to 108 mg kg−1 in 1992. In 1992, the highest rate of foliar B applications resulted in a leaf blade concentration of 154 mg B kg−1. Soil‐applied B did not alter leaf blade B concentration in 1991, but slightly increased leaf blade B concentration in 1992 from 54 to 71 mg kg−1. Soil B concentrations were higher during the midseason than the preplant period, suggesting that preplant soil B analysis may not accurately foreshadow soil B supply during the season. Soil B or foliar B applications did not affect boll retention percentage, flower number, or lint yield in either year. Supplemental B did not affect boll distribution in 1991, but in 1992, foliar B applications increased the percentage of fruit on monopodial branches. In both years, supplemental B did not greatly affect fiber properties with the exception that supplemental B increased fiber micronaire reading of Deltapine 20 in 1992. The results suggest that modern cultivars may not always need supplemental B when soil B concentration is moderately low.
Radiation‐Use Efficiency and Grain Yield of Maize Competing with Johnsongrass
Authors: Kiniry James R. 
Published: July 2010

AbstractAccurate simulation of the impact of weeds on crops requires adequate quantification of weed effects on crop biomass and on the partitioning of crop biomass into grain. The first objective of this study was to determine whether radiation‐use efficiency (RUE) values of maize (Zea mays L.) and johnsongrass [Sorghum halepense (L.) Pers.] grown in monoculture could be applied to these species grown in mixed plantings. The second objective was to investigate how maize yield and harvest index (HI) respond to johnsongrass competition. Monoculture plots of maize and johnsongrass and plots with the two species competing were established on Houston black clay (fine, montmorillonitic, thermic Udic Pellustert) in the field at Temple, TX, in 1991 and 1992. Sequential measurements of light interception (IPAR) and of biomass were used to calculate values for RUE prior to anthesis. Yield and HI of maize were measured after physiological maturity. Johnsongrass reduced grain yield of maize by 5% in 1991 and by 33 to 49% in 1992. The greater competition in the second year also reduced maize HI from 0.55 in the first year to 0.43 in the second. Values of RUE of maize and johnsongrass growing together were similar to weighted means of monoculture RUE values. The weights were the relative fraction of each species in the mixture. The measured values of maize‐johnsongrass mixtures differed from weighted means by 3 to 11% in both years.
Modifying Soil Nutrient Level Affects Soybean Insect Predators
Authors: Funderburk J. E. , Rhoads F. M. , Teare I. D. 
Published: July 2010

AbstractSoil nutrients can influence the population dynamics of arthropod pests and their natural enemies. Previous research has revealed that overfertilization increases the likelihood of pest outbreak in a subsequent soybean [Glycine max (L.) Merr.] crop following winter wheat (Triticum aestivum L.). Improving biological control from natural enemies is an important aspect of integrated pest management. Our objectives in this field study were to (i) determine the effect of soil nutrition on population densities of the predators Geocoris spp. (bigeyed bugs), Nabis and Hoplistoscelis spp. (damsel bugs), and spiders (Araneae) in a soybean canopy and (ii) relate densities of each predator to pest densities and determine if previously reported effects of overfertilization on pest densities were the indirect result of influences of soil nutrients on predator populations. Soil nutrient levels were four levels of P and three levels of K and Mg. The study was conducted in 1986 and 1987. High P favored population density of damsel bug nymphs in 1986 only, but populations were not significantly affected by K or Mg. High P significantly affected population densities of bigeyed bug nymphs each year. Density estimates of spiders were significantly increased by P only in 1986. Densities of spiders were not affected by K and Mg either year. Increased pest outbreaks from overfertilization of soybean were not the result of fertility effects on population densities of these major predators.