bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forage Production Estimates for Irrigated Meadows from Landsat Data1
Authors: Cipra J. E. , Noguerapena N. E. , Bryson M. C. , Lueking M. A. 
Published: July 2010

AbstractLandsat data have become increasingly useful in agriculture over the past several years. The satellite has been used in mapping soils, determining crop growth and condition, and here to estimate forage production in irrigated native hay meadows in the South Park region of Colorado.The objective of this study was to estimate forage production in irrigated meadows and surrounding rangeland using Landsat digital data and computer analysis. Biomass of standing, above‐ground, green vegetation was estimated by clipping and visual estimates for two growing seasons. Forage production data were compared to Landsat radiance data and ratio‐transformed data using linear regression and analysis of variance. Based on the existing conditions of this study, the use of Landsat data to estimate production appears feasible. However, production estimates will be most reliable if ground data are collected each year.
In Vivo Quality of Tall Fescue as Influenced by Season, Legumes, Age, and Canopy Strata1
Authors: Rayburn E. B. , Blaser R. E. , Fontenot J. P. 
Published: July 2010

AbstractFall‐grown tall fescue (Festuca arundinacea, Schreb.) provides a relatively inexpensive forage for winter grazing. Quality and yield of actively growing tall fescue increases when accumulated from August and harvested through time in the early fall. The effect of regrowth age on fall accumulated tall fescue quality has not been evaluated under similar harvest climates and animal performance on summer grown tall fescue is often low. Therefore a series of experiments were conducted to evaluate the in vivo quality of tall fescue in summer, alone and in combination with a legume, and to evaluate the in vivo quality of tall fescue of different regrowth ages harvested in December.Summer grown tall fescue, alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were fed alone and compared with 50:50 mixes of each legume with tall fescue. Orchardgrass (Dactylis glomerata L.) was also fed alone and with red clover during 1 year. Low in vivo digestible dry matter (DDM) of 35.8% for tall fescue 60 days old in 1975 was associated with droughtimposed dormancy. Nondormant, 40‐day‐old alfalfa regrowth was highly digestible (59.4% DDM). In 1976, the digestibilities of tall fescue and red clover were similar (54.8 and 53.9% DDM) and lower than that of orchardgrass (57.0% DDM). Consistent, nonsignificant trends in increased digestibility occurred with the inclusion of a legume which were sufficiently large to have potential economic consequences on animal production.In another experiment, tall fescue was accumulated from mid‐June, July, August, and September, with 112 kg N/ha applied in mid‐August, to evaluate the influence of age on in vivo quality when fed to sheep in early December. Quality decreased with increasing age. In 1975, June accumulated forage was significantly lower in quality than forage with shorter accumulation periods. In 1976, quality decreased with increased ages of the accumulated growth, ranging from 51.0 to 60.5% DDM for June and August accumulated forage, respectively. Quality of September accumulated forage was low (52.8% DDM), apparently due to high lignin and insoluble ash contents. Improved quality with shorter accumulation periods was offset by lower dry matter yields (5.2 vs. 2.2 metric tons/ha) and DDM yields were also reduced (1.7 vs. 1.2 metric tons/ha) from June to September, respectively. Accumulating tall fescue from as early as mid July did not decrease digestibility or intake sufficiently to make this practice impractical for winter grazing. Summer utilized tall fescue was lower in quality than that utilized in winter. There were significant correlations between DDM and TNC contents.
Leaf Water Potential, Stomatal Resistance, and Temperature Relations in Field‐Grown Soybeans1
Authors: Jung P. K. , Scott H. D. 
Published: July 2010

AbstractThere is a need for daily and seasonal measurements of the field water status of plants in order to characterize their response to soil water deficits. Measurements were made of leaf water potential (Ψ), stomatal diffusive resistance (R), and leaf temperature (T) of irrigated (I) and nonirrigated (N) ‘Forrest’ soybeans [Glycine max (L.) Merr.] grown on Crowley silt loam (a Typic Albaqualf), in a dry season. Values of Ψ in the N soybeans decreased earlier in the day and increased later in the afternoon than Ψ values of I soybeans. The stomates of N plants were partially closed during the daylight hours and closed earlier in the afternoon than stomates of I plants. Leaf temperatures of the N plants increased earlier in the morning and remained higher later in the afternoon than leaf temperatures of I plants. As the drought intensified, differences in Ψ, R, and T between the N and I soybeans increased. Maximum differences during the day were approximately ∆Ψ = −4 bars, ∆R = 6.0 sec/cm, and ∆T = 5.5 C and were usually found at midday and midafternoon late in the season. Generally, the differences in these parameters between moisture regimes were lower at midmorning. The differences in these plant water and temperature parameters were reflected in lower production of total dry matter and seed.
Measuring Soil Nitrogen Mineralization Under Field Conditions1
Authors: Westermann D. T. , Crothers S. E. 
Published: July 2010

AbstractThe amount and rate of soil N mineralization are important components that can be used to predict preplant N fertilizer application and to evaluate the need for N fertilization during crop growth. This study‘s purpose was to evaluate the buried polyethylene bag technique as a method for characterizing the N mineralized under field conditions during the cropping season. Soil (Xerollic Calciorthids) was placed in polyethylene bag and buried in the 0 to 45 cm root zone of fallowed soils and where corn (Zea mays L.) and potato (Solanum tuberosum L.) were being grown. The NO3‐N content of the soil in the bags was compared with that in the root zone at selected time intervals (10 to 14 days) from April to October.The soil NO3‐N concentrations in the buried polyethylene bags were similar to those in irrigated fallow soils from April to October after correction for different soil water contents. The N‐mineralization rate between sampling intervals had an average temperature coefficient (Q10) of 2.3 between 10 C and 30 C. The relative N‐mineralization rate was proportional to the soil water content expressed as a percentage of the available waterholding capacity. The N uptake by corn and potato crops predicted from NO3‐N changes in the rooting zone and in the buried polyethylene bags resembled those measured by plant sampling. The buried polyethylene bag technique has potential for monitoring the soil N‐mineralization process during the cropping season and for estimating N uptake by crops. It also provides an alternative method for estimating soil N availability for future crops and its use should maximize N‐fertilizer efficiencies.
Effects of Management Practices on Reflectance of Spring Wheat Canopies1
Authors: Daughtry C. S. T. , Bauer M. E. , Crecelius D. W. , Hixson M. M. 
Published: July 2010

AbstractAnalyses of multispectral measurements from satellites offer the potential to monitor and inventory crop production. The crop canopy is a dynamic entity influenced by many cultural and environmental factors. In order to quantify and understand some of these potential sources of variation in spectral measurements of crops, an experiment was conducted on a Williams loam (fine−loamy, mixed Typic Argiborolls) at the Williston, North Dakota, Agricultural Experiment Station in 1977. The effects of soil moisture, planting date, nitrogen fertilization, and cultivar on reflectance of spring wheat (Triticum aestivum L.) canopies were investigated. Spectral measurements were acquired on eight dates throughout the growing season with a radiometer (Exotech 100 A) in four wavelength bands (0.5 to 0.6, 0.6 to 0.7, 0.7 to 0.8, 0.8 to 1.1 µm) at 3.5 m above the plots. On the days spectral data were taken, measurements of crop maturity stage, leaf area index, biomass, plant height, percent soil cover, and soil moisture were also taken.In this experiment, planting date and available soil moisture were the primary agronomic factors affecting reflectance of spring wheat canopies from tillering to maturity. Comparisons (R2) of treatments indicated that during seedling and tillering stages, planting date was associated with 36 and 85% of variation in red (0.6 to 0.7 µm) and near infrared (0.8 to 1.1 µm) reflectances, respectively. As the wheat headed and matured, less variation in reflectance was associated with planting date and more with available soil moisture. By mid July soil moisture accounted for 73 and 69% of the variation in reflectance in red and near infrared bands, respectively. Differences in spectral reflectance among treatments were attributed to changes in leaf area index (LAI), biomass, and percent soil cover. Cultivar and N fertilization rate had little association with the variation in reflectance of these canopies. Agronomic practices resulting in differences in LAI, biomass, and percent soil cover potentially can be monitored by remote sensing and this information may be useful in estimating crop production.
Association of Epichloe Typhina Fungus and Steer Performance on Tall Fescue Pasture
Authors: Hoveland C. S. , Haaland R. L. , King C. C. , Anthony W. B. , Clark E. M. , McGuire J. A. , Smith L. A. , Grimes H. W. , Holliman J. L. 
Published: July 2010

AbstractAnti‐quality components factors associated with poor animal performance on tall fescue (Festuca arundinacea Schreb.) pasture may include mycotoxins produced by the fungus Epichloe typhina (Pers.) Tul. The original objectives of this study were to compare steer performance on pastures of different grass species, but large differences in animal performance occurred among paddocks in different replications of the tall fescue‐dallisgrass (Paspalum dilatatum Poir.) treatment. The experiment was conducted in west central Alabama on replicated 1.2 ha paddocks containing two calcareous soils, Sumter clay (Rendolic Eutrochrept, fine silty, carbonatic, thermic) and Houston clay (Typic Chromudert, very fine montmorillonitic, thermic). The tall fescue‐dalligrass pastures were fertilized with 336 kg N/ha annually and grazed with yearling steers for 225 days annually for 3 years. The three tall fescue‐dallisgrass paddocks contained very little dallisgrass, but animal performance differed greatly on them. Steers averaged 453 kg gain/ha on two paddocks with an average daily gain (ADG) of 0.68 kg, while steers on the other paddock averaged only 360 kg gain/ha with an ADG of 0.45 over the 3‐year period. Dry matter digestibility of the forage averaged 63% for the high performance paddocks and 58% for the low performance paddock. Mineral content of the forage was similar on all paddocks. Tall fescue forage in the low performance paddock was heavily infested with Epichloe typhina fungus while the other two paddocks were lightly infested with the fungus. Results of the study suggest that this fungus may be associated with low performance of steers on tall fescue pasture.
Reproductive Abscission Levels and Patterns for Eleven Determinate Soybean Cultivars1
Authors: Wiebold W. J. , Ashley D. A. , Boerma H. R. 
Published: July 2010

AbstractAlthough soybeans (Glycine max L. Merrill) are considered to have relatively high levels of reproductive abscission, most studies have used only one or two cultivars and cultivar differences for abscission have rarely been reported. This study determined the abscission levels for 11 field‐grown, determinate soybean cultivars (Maturity Groups V, VI, VII, VIII) and tested for cultivar differences in abscission. Numbers of flowers and young pods (2 cm long) produced and pods at harvest were determined for 15 plants of each cultivar. New flowers were counted on alternate days; whereas, young pods were counted weekly. Production of each reproductive structure was recorded for each node (including any branches) of each plant. Seed number and weight at harvest were also determined. Cultivars differed in number of flowers, young pods, and pods produced per plant. Number of flowers roduced per plant rangaf from 170 to 332 and average 232. Number of pods at harvest ranged from 41 to 90 and averaged 57 per plant. Cultivars also differed in the percentage of fruit less than 2 cm in length which abscissed and percent total abscission. Percent total abscission rang ed from 67% for ‘McNair 800’ to 82% for ‘Hale 3’ and averaged 75% Small pods (less than 2 cm in length) and flowers accounted for an average of 87% of the total abscission. Flower production of most cultivars was concentrated in the top two‐thirds of the canopy. The to one‐thiid canopy region of most cultivars accounted for a majority of the harvestable pods. Percent total abscission increased with depth into the canopy. Yield (seed weight per plant) was related positively (r= 0.50) to numbers of flowers produced. It is concluded that determinate soybean cultivars differ in percent abscission. That a deficit of available carbohydrate is at least one of the factors involved in soybean reproductive abscission is discussed.
Heat Tolerance of Kentucky Bluegrasses, Perennial Ryegrasses, and Annual Bluegrass1
Authors: Wehner D. J. , Watschke T. L. 
Published: July 2010

AbstractUse of cool‐season turfgrasses in transitional environments is limited, in part, by their heat tolerance. Development of a rapid heat tolerance screening technique would be of value in determining the potential of turfgrasses for use in warmer areas.The heat tolerance of 22 Kentucky bluegrass (Poa pratensis L.) cultivars, Poa annua L., and four perennial ryegrass cultivars (Lolium perenne L.) was evaluated by exposing plants for 30 min to temperatures ranging from 41 to 49 C in single degree intervals. Ten‐week‐old plants, which had been grown under a low level of N fertilization and watered infrequently to maximize heat tolerance development, were sealed in plastic bags, placed in a constant temperature water bath for treatment, and then replanted. Recovery was evaluated by visually rating the plants 4 weeks afte treatment or by harvesting and weighing plants 2 weeks after treatment and expressing the weight as a percentage of the weight of a nonstressed control (referred to as recovery weight). Cultivar comparisons were based on the average recovery weight over a given temperature range.Initial injury occurred at 41 to 43 C with complete kill at 47 to 49 C. Kentucky bluegrass was more heat tolerant than Poa annua L. and perennial ryegrass. Heat tolerance of the latter two species was approximately equal. The Kentucky bluegrass cultivars tested were similar in heat tolerance. Among the ryegrasses, “‘Loretta’ was less heat tolerant than ‘Diplomat’, ‘Pennfine’, and ‘Citation’. Of all the grasses, ‘Sydsport’ Kentucky bluegrass ranked the highest and Loretta perennial ryegrass the lowest in heat tolerance. The correlation between dilute acid extractable carbohydrate reserves and recovery weight for these five cultivars was not significant. There was a significant negative correlation between recovery weight and Fe and A1 concentration.
An Index of Nutrient Efficiency and Its Application to Corn Yield Response to Fertilizer N. I. Derivation, Estimation, and Application1
Authors: Capurro Eduardo , Voss Regis 
Published: July 2010

AbstractImproving the efficiency of use of applied nutrients in crop production are agronomic, economic, and environmental goals. The purpose of this study was to develop a methodology for studying the efficiency of fertilizer use, to apply it to the yield response of corn (Zea mays L.) to fertilizer N, and to use these results to estimate fertilizer N needs for a range of relative corn yields.The derived nutrient efficiency was divided into two components: (a) one depending on the level of relative yield expressed as a percentage of maximum yield (hence, it depends on the nutrient rate and can be estimated from soil test or plant analysis values) and (b) a component termed relative efficiency index (Ex), which can be defined generally as the nutrient efficiency at 99% of maximum yield and is independent of the nutrient rate. for the quadratic polynomial, Ex is equal to one‐fifth of the product of the square roots of the quadratic coefficient and of the maximum yield.Relative efficiency index for N, EN, were obtained from quadratic regressions of corn yield on fertilizer N rates for each of 33 experiments conducted on well, moderately well, and somewhat poorly drained soils in Iowa. EN was closely related to the square root of the quadratic coefficient. Values of EN ranged from 2.5 to 9.3, and maximum grain yields varied from 3,600 to 10,200 kg/ha. Nutrient efficiencies were calculated from given values of EN and relative yield, e.g., this gave efficiencies in kg grain/kg N of 14 for EN of 2 and 42 for EN of 6 at a relative yield of 50%. The required increase in N rate for economic optimum yield was calculated from given values of EN, relative yield, maximum yield, and the N to corn price ratio.The Ex seems to be a useful index to characterize the response of crop yields to applied nutrients and to derive yield‐applied nutrient relationships.
Nitro Compounds in Indigofera Species1
Authors: Williams M. C. 
Published: July 2010

AbstractThe genus Indigofera consists of approximately 700 species of tropical and subtropical origin. Several of these species are being investigated for possible introduction into the southern United States. Leaves of Indigofera species grown in the field and greenhouse, or sampled from herbarium specimens, were analyzed colorimetrically for aliphatic nitro compounds. Aliphatic nitro compounds were found in 64 of 250 species of Indigofera in concentrations of 2 to 12 mg NO2/g of plant. Four species that assayed 4 to 12 mg NO2/g were moderately toxic to 1‐week‐old chicks when administered as an aqueous extract. Hairy indigo (Indigofera hirsuta L.), a commercial variety already introduced, did not contain nitro compounds and was nontoxic to chicks. Indigofera species proposed for introduction into the United States should be examined for the presence and concentration of nitro compounds.
Establishment of Sod‐seeded Alfalfa at Various Levels of Soil Moisture and Grass Competition1
Authors: Groya F. L. , Sheaffer C. C. 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.) establishment in competition with grass sods is not always successful, especially under conditions of soil moisture deficiency. Our objective was to evaluate the effect of soil moisture concentration and grass competition on alfalfa establishment and yield when it was interseeded into perennial grass sods.In a greenhouse experiment, alfalfa was seeded into Kentucky bluegrass (Poa pratensis L.) or smooth bromegrass (Bromus inermis Leyss.) sods which had been sprayed with 0, 0.6, and 2.2 kg/ha glyphosate [N‐(phosphonomethyl)glycine]. Three soil moisture regimes were established by watering to field capacity when soil moisture tensions reached 0.1, 1, and 12 bars. Grass‐shading treatments were also applied.At two field locations alfalfa was seeded into an unimproved Kentucky bluegrass, smooth bromegrass, and quackgrass (Agropyron repens L.) pasture and into a smooth bromegrass pasture. The soil at both locations was a Waukegan silt loam (Typic Hapludoll). Three levels of grass suppression were obtained by spraying with 0, 0.8, and 3.3 kg glyphosate/ha. Soil moisture regimes consisted of watering to field capacity when soil moisture tension reached 1 and 15 bars.Under shaded conditions in the greenhouse and with low grass suppression (no glyphosate) in the field, moisture did not significantly affect alfalfa establishment or dry matter yield. However, when shading was eliminated or grass suppression increased, low soil moisture tensions resulted in increased legume yields.In the greenhouse, alfalfa dry matter yields and root weights were generally greater when it was seeded into Kentucky bluegrass compared to smooth bromegrass. Smooth bromegrass was more tolerant of glyphosate application than Kentucky bluegrass. When seeded into smooth bromegrass, alfalfa yields from low and medium moisture level treatments were not significantly different, but when seeded into Kentucky bluegrass yields from high and medium moisture levels were significantly greater than for the low moisture treatment.Our results show that both adequate soil moisture and reduced grass competition for light are important for successful alfalfa sod‐seeding.
Effect of Time and Amount of Nitrogen Uptake on Sugarbeet Growth and Yield1
Authors: Carter J. N. , Traveller D. J. 
Published: July 2010

AbstractSugarbeet (Beta vulgaris L.) root quality has been steadily decreasing since the early 1950's with increased use of N fertilizer. Since the extent of these decreases may be associated with the time and amount of N uptake, the objective of this study was to evaluate the effects of several rates and times of N fertilizer applications and N uptake by sugarbeets on seasonal growth rates, sucrose percentage and accumulation, dry matter production, and partitioning of the photosynthate.Sugarbeets were grown under field conditions on a Portneuf silt loam soil (Durixerollic Calciorthids, coarsesilty, mixed, mesic) near Twin Falls, Idaho, in 1977, using four N rates, each applied preplant, mid‐June, mid‐July, and mid‐August. Root yields, sucrose concentration and yield, dry matter production, leaf area index, and plant N uptake were determined from samples taken throughout the season. Adding N fertilizer above that needed for optimum plant growth or delaying N application until midseason caused a greater proportion of the photosynthate to be used for increased top growth at the expense of dry matter and sucrose accumulation in the roots. Sucrose accumulation was maximum from late July until early September; therefore, during this period, addition of N and N uptake by the plant caused the greatest decrease in sucrose accumulation and production at harvest. Increasing N levels decreased sucrose concentrations during the season and at harvest because of 1) increased moisture level of roots, and 2) dry matter produced and accumulated in the roots having a decreased sucrose concentration. The rate of accumulation of stored sucrose was reduced by midseason N application, but stored sucrose was not used for increased growth of beet tops. Excess and late N applications also increased impurities in the beet root, decreasing extractability of stored sucrose, which further decreased refined sucrose production. Early application of N fertilizer at optimum levels should maximize refined sucrose production.