A mathematical study of the generation of microseisms by waves at sea

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The Value of Grazed Corn Residue for Crop and Cattle Producers

The Western Corn Belt has historically been corn and wheat cropping systems with cattle integrated on nearby grasslands. Recent agricultural production data ranked Nebraska, South Dakota, Kansas, and North Dakota in the top 10 states for both corn and beef cattle production in the United States. In 2017, these four states had about 20% of the beef cow inventory in the United States with Nebraska alone having 1.9 million beef cows (USDA National Agricultural Statistics Service, 2018). Forage-based livestock production is a fundamental component of these agricultural economies. However, a large quantity of grasslands in this region were converted into annual crops during the mid-2000s (Wright and Wimberly, 2013). To maintain the efciencies of beef cattle production systems, synergistic use of forage resources in a sustainable manner is essential. In addition to grasslands, this includes the complementary use of corn residue for grazing during the winter months. In this article, we provide an economic assessment of current corn residue grazing in Nebraska as well as some comparisons to Kansas, South Dakota, and North Dakota

Ag Lenders Panel Provides Insight into Beef Systems Initiative

In 2017, the University of Nebraska-Lincoln Institute of Agricultural and Natural Resources (IANR) and Nebraska Extension made a commitment to implement a multidisciplinary Beef Systems Initiative (BSI). The BSI is administered by the Center for Grassland Studies and is comprised of six projects designed to develop and support the implementation of beef production systems that optimize feed resource use, natural resource conservation, and producer success in Nebraska through improved management of perennial grasslands and systems of integrated crop-beef cattle production. In addition to the BSI, a parallel project funded by the Foundation for Food and Agriculture Research (FFAR) is studying the best practices for incorporating beef cattle into cropping systems while improving ecosystem services to ensure sustainability. Both of these efforts include components focused on producer and community outreach through Nebraska Extension. To this end, an agricultural lenders panel and five geographically identified producer panels have been formed to provide input and feedback on the project results as they become available. Recently, the lenders panel met for the first time to provide their perspectives about the important information that should be communicated to producers who are considering developing an integrated beef enterprise

Morphological Development Rates of Perennial Forage Grasses

The objective of this study was to determine the rate of change in the morphological development of switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman). Pure stands of each species were sampled at weekly intervals in 1990 and 1991 at Mead, NE, and morphologically classified as mean stage count (MSC) and mean stage weight (MSW). Linear day of the year equations accounted for 94% of the variation in switchgrass MSC and MSW. Switchgrass MSC and MSW increased at an average rate of 0.0204 and 0.0234 units per day, respectively. Linear day of the year equations accounted for 73 and 84% of the variation in big bluestem MSC and MSW, respectively. Big bluestem MSC and MSW increased at an average rate of 0.0147 and 0.0215 units per day, respectively. The morphological development of switchgrass and big bluestem can be reliably predicted for adapted cultivars in the central Great Plains using day of the year due to the determinate growth habit of these grasses and their strong response to photoperiod

Tiller Demographics and Leaf Area Index of Four Perennial Pasture Grasses

Developing grazing systems requires basic information on the growth and development of adapted species. The objective of this field study was to determine seasonal tiller demographics and leaf area index (LAI) of intermediate wbeatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey], smooth bromegrass (Bromus inermis Leyss.), switchgrass (Panicum virgatum L.), and big bluestem (Andropogon gerardii Vitman) tiller populations. This study was conducted in 1992 and 1993 near Mead, NE, on a silty clay loam soil (Typic Argiudoll) as a randomized complete block. Monocultures were harvested six times each year for tiller demographics. Additionally, mean stage count (MSC), a quantified estimate of tiller population maturity, was determined at each harvest. The The LAI was indirectly measured using a canopy analyzer at 7- to 14-d intervals. Tiller density for all species generally declined as MSC increased. Tiller demographics were highly variable by year for intermediate wheatgrass and smooth bromegrass, which indicates that grazing management should be based on current tiller populations. Density of vegetative tillers declined most rapidly for smooth bromegrass, followed by intermediate wheatgrass, switchgrass, and big bluestem. Switchgrass and big bluestem tiller demographics were more uniform and predictable across years than intermediate wheatgrass and smooth bromegrass. The LAI for all species increased as MSC increased. Maximum The LAI for intermediate wheatgrass, smooth bromegrass, switchgrass, and big bluestem in 1992 was 4.7,5.1,4.9, and 5.8, respectively. Integrating tiller demographics and The LAI suggests that initial grazing readiness starts with smooth bromegrass in early spring, followed by intermediate wheatgrass in about 2 wk, switchgrass in late spring, and big bluestem in early summer

Electron Beam Irradiation Dose Dependently Damages the Bacillus Spore Coat and Spore Membrane

Effective control of spore-forming bacilli begs suitable physical or chemical methods. While many spore inactivation techniques have been proven effective, electron beam (EB) irradiation has been frequently chosen to eradicate Bacillus spores. Despite its widespread use, there are limited data evaluating the effects of EB irradiation on Bacillus spores. To study this, B. atrophaeus spores were purified, suspended in sterile, distilled water, and irradiated with EB (up to 20 kGy). Irradiated spores were found (1) to contain structural damage as observed by electron microscopy, (2) to have spilled cytoplasmic contents as measured by spectroscopy, (3) to have reduced membrane integrity as determined by fluorescence cytometry, and (4) to have fragmented genomic DNA as measured by gel electrophoresis, all in a dose-dependent manner. Additionally, cytometry data reveal decreased spore size, increased surface alterations, and increased uptake of propidium iodide, with increasing EB dose, suggesting spore coat alterations with membrane damage, prior to loss of spore viability. The present study suggests that EB irradiation of spores in water results in substantial structural damage of the spore coat and inner membrane, and that, along with DNA fragmentation, results in dose-dependent spore inactivation

Predicting Developmental Morphology in Switchgrass and Big Bluestem

Switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) are important warm-season grasses in livestock production systems in the central and eastern USA. The objectives of this study were to quantify the morphological development of ‘trailblazer’ switchgrass and \u27Pawnee\u27 big bluestem and to evaluate day of the year (DOY) and growing degree day (GDD) as predictors of switchgrass and big blnestem morphological stage. Pure stands of each species were sampled at weekly intervals in 1990 and 1991 at Mead, NE, and classified as to mean stage count (MSC) and mean stage weight (MSW). Prediction equations for MSC and MSW were developed based on DOY and GDD. The validation study was harvested at 2-wk intervals in 1992 and 1993 at Mead, NE, and Manhattan, KS, and classified as to MSC and MSW. Switchgrass and big bluestem MSC and MSW were related linearly in all environments. Linear DOY calibration equations accounted for 96% of the variation in switchgrass MSC across four environments, which indicates that switchgrass development was related to photoperiod and that general management recommendations could be based on DOY in the central Great Plains. Quadratic GDD calibration equations accounted for 83% of the variation in big bluestem MSC across four environments, which indicates that big bluestem development is more difficult to predict and management recommendations in the central Great Plains should be based on morphological development (which is best predicted by GDD). The comprehensive growth staging system gave repeatable results for quantifying the morphological development of switchgrass and big blnestem. The morphological development of switchgrass and big bluestem can be reliably predicted for adapted cultivars in the central Great Plains during years with near-normal precipitation using DOY and GDD because of the determinate growth habit of these grasses

Impact of Grazing Spring Rye on Subsequent Crop Yields and Profitability

Steers (729 ± 19 lb BW) grazed in two November-planted cereal rye fields for 22 d in April, either with or without an ionophore in their free choice mineral supplement. Subsequent corn yields were measured to assess impact of planting cereal rye as a cover crop (not grazed) or grazing the rye compared to a no rye control. There was no statistical impact of rye or grazing on subsequent corn yield. Supplying an ionophore in the mineral did not uniformly improve gains across fields. However, gains were high at 3.2 lb/d and were able to offset the cost of planting rye

Developmental Morphology Of Tropical Sorghum And Sorghum X Sudangrass

Tropical sorghum and sorghum x sudangrass are known to be efficient scavengers of soil nitrogen and are important forage crops in the U.S. Nitrate contamination of groundwater due to disposal of organic wastes and excessive fertilization is a major concern in the Central Great Plains. A common disposal method of municipal wastes is application to fallow cropland. Quantification of the developmental morphology of tropical sorghum and sorghum x sudangrass is important to developing management strategies that allow multiple applications of organic wastes to optimize nitrogen removal and dry matter production. The objective of this study was to quantify the developmental morphology of tropical sorghum and sorghum x sudangrass irrigated at levels approximating transpiration and evaporative demand. Tropical sorghum mean stage by count (MSC) was 33% lower than MSC for sorghum x sudangrass in September. Leaf-to-stem ratio was greater for tropical sorghum than sorghum x sudangrass throughout most of the growing season. Dry matter per plant was as much as 30% greater for sorghum x sudangrass, although values were nearly equal at the end of the growing season

Developmental Morphology Of Tropical Sorghum And Sorghum X Sudangrass

Tropical sorghum and sorghum x sudangrass are known to be efficient scavengers of soil nitrogen and are important forage crops in the U.S. Nitrate contamination of groundwater due to disposal of organic wastes and excessive fertilization is a major concern in the Central Great Plains. A common disposal method of municipal wastes is application to fallow cropland. Quantification of the developmental morphology of tropical sorghum and sorghum x sudangrass is important to developing management strategies that allow multiple applications of organic wastes to optimize nitrogen removal and dry matter production. The objective of this study was to quantify the developmental morphology of tropical sorghum and sorghum x sudangrass irrigated at levels approximating transpiration and evaporative demand. Tropical sorghum mean stage by count (MSC) was 33% lower than MSC for sorghum x sudangrass in September. Leaf-to-stem ratio was greater for tropical sorghum than sorghum x sudangrass throughout most of the growing season. Dry matter per plant was as much as 30% greater for sorghum x sudangrass, although values were nearly equal at the end of the growing season