Earth Sciences Commons^™

Grassland Plant Diseases: Management And Control, S. Chakraborty

IGC Proceedings (1977-2023)

Grasslands cover 40% of the earth’s surface and support animal-based industries; maintain soil cover, watersheds and biodiversity; sequester atmospheric carbon for storage in the soil; and provide tourism and leisure income. Diseases continue to decrease herbage and seed yield and reduce nutritive value and palatability of grasslands to impact on animal health and productivity but realistic data on loss are hard to find. Although principles of disease management remain the same, strategies used in crop protection can not be directly applied to grasslands due to differences in heterogeneity, population size, density and spatial distribution and population continuity. Low per hectare …

Soil Carbon And Nitrogen Dynamics After Pasture Installation In The Amazon Region, C. C. Cerri, M. Bernoux, C. E. P. Cerri

IGC Proceedings (1977-2023)

The objective of this paper is to present the soil carbon (C) and nitrogen (N) dynamics in a chronosequence made of a forest and pastures of different ages established in a Oxisol in the Western Brazilian Amazon Basin. The results of soil Carbon and Nitrogen stocks and gases fluxes were discussed. Stable ¹³C isotopic technique was used to calculate for a determinate age of pasture installation, the proportion of soil C remaining from the forest system and the proportion of soil C introduced by the grasses of the pasture system. The C lost from the original pool under the …

Micronutrients In Grassland Production, U. C. Gupta, F. A. Monteiro, J. C. Werner

IGC Proceedings (1977-2023)

Micronutrients, also known as trace minerals, which chiefly include boron (B), molybdenum (Mo), copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe), are required in extremely small quantities by crops and livestock. Their name, however, is not meant to imply their role is minor. Their lack, e.g., can cause serious crop production problems in forages and health disorders in livestock. This presentation includes the response of forage legumes and grasses to micronutrients, their deficiency and sufficiency levels in forages and their sufficiency levels in livestock. Forage legumes are more responsive to micronutrients, particularly B and Mo, than grasses. There are …

Pasture Seed Production Technology In Brazil, Ronaldo Pereira De Andrade

IGC Proceedings (1977-2023)

Efficient and low cost production systems, which rely on the use of cultivated pastures, are the basis of beef and milk production in Brazil. The success of these pasture-based systems would not be possible without the support of an aggressive and dynamic pasture seed production sector to supply the internal demand, which is estimated to be around 90000 tons per year. The market is dominated by grass species and among them, Brachiaria. brizantha cv. Marandu accounts for more than 80% of the total seed volume in the market. Seed production systems in Brazil vary from highly specialized to opportunistic accordingly …

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Shallow Rupture Propagation Of Pleistocene Earthquakes Along The Hurricane Fault, Ut, Revealed By Hematite (U-Th)/He Thermochronometry And Textures, Madison P. Taylor, Alexis K. Ault, Margaret L. Odlum, Dennis L. Newell

Geoscience Faculty Research

The material properties and distribution of faults above the seismogenic zone promote or inhibit earthquake rupture propagation. We document the depths and mechanics of fault slip along the seismically active Hurricane fault, UT, with scanning and transmission electron microscopy and hematite (U-Th)/He thermochronometry. Hematite occurs as mm-scale, striated patches on a >10 m2 thin, mirror-like silica fault surface. Hematite textures include bulbous aggregates and cataclasite, overlain by crystalline Fe-oxide nanorods and an amorphous silica layer at the slip interface. Textures reflect mechanical, fluid, and heat-assisted amorphization of hematite and silica-rich host rock that weaken the fault and promote rupture propagation. …

Meeting The Changing Need For Herbage Seed Quality Assurance In The 21st Century, D. S. Loch, K. G. Boyce

IGC Proceedings (1977-2023)

Quality assurance is a key element in the herbage seed supply chain. The measurement and management of seed quality is discussed in terms of its four main parameters - genetic, physical, vital, and phytosanitary quality - which provide information on the expected performance of herbage seed when sown in the field. During the past century, seed quality management systems have evolved in response to national and regional differences in economic development, crop characteristics, merit testing, and the demands of international trade. The pace of change in the management of seed quality assurance has intensified in developed countries over the past …

Novel Grasses And Legumes Germplam: Advances And Perspectives For Tropical Zones, E. A. Pizarro

IGC Proceedings (1977-2023)

It has been the aim, in the present article, to bring together as much as possible scientific evidence and experience in new available germplasm for tropical zones.

The economic importance of the Brachiaria, Paspalum and Pennisetum grasses is well established. New germplasm has become available since 1980. This paper reviews evaluations of Brachiaria accessions in humid lowlands and savannas of tropical America. The selection criteria need to be revised. Also, it is necessary to expose the new material as early as possible to farmers in order to select new germplasm with high chances of adoption.

Within the genus Paspalum …

Temperate Forage Grass-Legume Mixtures: Advances And Perspectives, A. S. Laidlaw, N. Teuber

IGC Proceedings (1977-2023)

The paper summarises some of the advances which have been made a) in increasing understanding of the grass-legume association, especially grass-white clover, so that the association can be more predictably exploited and b) in overcoming limitations in the use of such mixtures. The contribution which forage legumes make to the N economy of mixtures is reviewed with estimates approaching 400 kg N ha^-1 for some. Uptake by grass of legume- derived N (N transfer) reduces soil mineral N levels and increases the proportion of fixed N in the total legume N relative to legume monoculture. Although N transfer also …

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The Relative Importance Of Wind-Driven And Chimney Effect Cave Ventilation: Observations In Postojna Cave (Slovenia), Lovel Kukuljan, Franci Gabrovsek, Matthew Covington

International Journal of Speleology

Density-driven chimney effect airflow is the most common form of cave ventilation, allowing gas exchange between the outside and the karst subsurface. However, cave ventilation can also be driven by other mechanisms, such as barometric changes or pressure differences induced by the outside winds. We discuss the mechanism and dynamics of wind-driven ventilation using observations in Postojna Cave, Slovenia. We show how seasonal airflow patterns driven by the chimney effect are substantially modified by outside winds. Wind flow over irregular topography forms near-surface air pressure variations and thus pressure differences between cave entrances at different locations. These pressure differences depend …

Effect Of Sources And Rates Of Nitrogen On Nutrients Extraction In Coastcross Pastures, A. C. Primavesi, O. Primavesi, L. De A. Corrêa, H. Cantarella, A. G. Da Silva, A. R. Freitas

IGC Proceedings (1977-2023)

The contents and the extraction of mineral nutrients were determined in a coastcross pasture established on a dark red latosol (Hapludox), in São Carlos, SP, Brazil, under tropical altitude climate, receiving five rates of urea and ammonium nitrate, applied on surface. There were differences (P< 0.05) among sources and rates of N. Nutrients extraction increased with the nitrogen levels. Especially high were total N (319 and 446 kg ha^-1) and K (341 and 467 kg ha^-1) extractions. When forage yield was high (treatment with 500 kg of N ha^-1) and for both fertilizers, macronutrients extraction was greater for K and N, followed by Ca, S, P and Mg. Micronutrients extraction occurred in the following decreasing order: Fe, Mn, …

Dry Matter Production Response Of Coastcross (Cynodon Dactylon (L.) Pears) To Sources And Rates Of Nitrogen, L. De A. Corrêa, H. Cantarella, A. C. Primavesi, O. Primavesi, A. R. Freitas, A. G. Da Silva, E. B. Pott

IGC Proceedings (1977-2023)

Dry matter production of a coastcross pasture grown on a dark red latosol (Hapludox), in São Carlos, São Paulo State, Brazil, under tropical altitude climate, was evaluated. The goal was to verify the efficiency of N rates as urea and ammonium nitrate: 0, 25, 50, 100 and 200 kg ha^-1 per cutting, in five periods. Both sources were equally efficient. The mean N rates, which produced 80% of maximum forage yield, were 78 and 58 kg N ha^-1, respectively, for urea and ammonium nitrate, and were related to dry matter yields of 2,769 and 3,347 kg ha …

Combination Of High Specific Activity Carbon-14 Labeling And High Resolution Mass Spectrometry To Study Pesticide Metabolism In Crops: Metabolism Of Cycloxaprid In Rice, Dahang Shen, Zhijiang Lu, Jiayin Zhong, Sufen Zhang, Qingfu Ye, Wei Wang, Jay Gan

Environmental Science and Geology Faculty Research Publications

The study of pesticide metabolism in crops is critical for assessing the mode of action and environmental risks of pesticides. However, the study of pesticide metabolism in crops is usually complicated and it is often a daunting challenge to accurately screen the metabolites of novel pesticides in complex matrices. This study demonstrated a combined use of high-specific activity carbon-14 labeling and high-resolution mass spectrometry (HSA-¹⁴C-HRMS) for metabolism profiling of a novel neonicotinoid cycloxaprid in rice. By generating the characteristic radioactive peaks on the liquid chromatogram, the use of ¹⁴C can eliminate the severe interference of complex matrices …

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Trace Fossils, Algae, Invertebrate Remains And New U-Pb Detrital Zircon Geochronology From The Lower Cambrian Torneträsk Formation, Northern Sweden, Stephen Mcloughlin, Vivi Vajda, Timothy P. Topper, James L. Crowley, Fan Liu, Ove Johansson, Christian B. Skovsted

Geosciences Faculty Publications and Presentations

Nineteen ichnotaxa, together with algal and invertebrate remains, and various pseudo-traces and sedimentary structures are described from the Torneträsk Formation exposed near Lake Torneträsk, Lapland, Sweden, representing a marked increase in the diversity of biotic traces recorded from this unit. The “lower siltstone” interval of the Torneträsk Formation contains mostly simple pascichnia, fodinichnia and domichnia burrows and trails of low-energy shoreface to intertidal settings. The assemblage has very few forms characteristic of high-energy, soft-sediment, foreshore or upper shoreface environments (representative of the Skolithos ichnofacies).

Uranium-lead (U-Pb) LA-ICPMS analysis of zircon from a thin claystone layer within the “lower siltstone” interval …

Lethal Microbial Blooms Delayed Freshwater Ecosystem Recovery Following The End-Permian Extinction, Chris Mays, Stephen Mcloughlin, Tracy D. Frank, Christopher R. Fielding, Sam M. Slater, Vivi Vajda

Department of Earth and Atmospheric Sciences: Faculty Publications

Harmful algal and bacterial blooms linked to deforestation, soil loss and global warming are increasingly frequent in lakes and rivers. We demonstrate that climate changes and deforestation can drive recurrent microbial blooms, inhibiting the recovery of freshwater ecosystems for hundreds of millennia. From the stratigraphic successions of the Sydney Basin, Australia, our fossil, sedimentary and geochemical data reveal bloom events following forest ecosystem collapse during the most severe mass extinction in Earth’s history, the end- Permian event (EPE; c. 252.2 Ma). Microbial communities proliferated in lowland fresh and brackish waterbodies, with algal concentrations typical of modern blooms. These initiated before …

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Moving On Up: Vertical Distribution Shifts In Rocky Reef Fish Species During Climate-Driven Decline In Dissolved Oxygen From 1995 To 2009, Erin L. Meyer-Gutbrod, Li Kui, Mary Nishimoto, Linda Snook, Milton Love

Faculty Publications

Anthropogenic climate change has resulted in warming temperatures and reduced oxygen concentrations in the global oceans. Much remains unknown on the impacts of reduced oxygen concentrations on the biology and distribution of marine fishes. In the Southern California Channel Islands, visual fish surveys were conducted frequently in a manned submersible at three rocky reefs between 1995 and 2009. This area is characterized by a steep bathymetric gradient, with the surveyed sites Anacapa Passage, Footprint and Piggy Bank corresponding to depths near 50, 150 and 300 m. Poisson models were developed for each fish species observed consistently in this network of …

Ammonia Losses By Volatilization From Coastcross Pasture Fertilized With Two Nitrogen Sources, H. Cantarella, L. De A. Corrêa, A. C. Primavesi, O. Primavesi, A. R. De Freitas, A. G. Da Silva

IGC Proceedings (1977-2023)

Ammonia losses by volatilization from five rates of urea or ammonium nitrate surfaceapplied to coastcross pasture, grown on a dark red latosol (Hapludox) in São Carlos, SP, Brazil, under tropical altitude climate, were measured. Volatilized ammonia was absorbed in traps placed on soil surface. The mean losses from urea applied after five successive cuttings of the grass were 15, 24, 34, and 40% for N rates of 25, 50, 100 and 200 kg N ha-1 per cutting, respectively.

Assessing The Effect Of N And P Supply On Dry Matter Yield Of Three Tropical Grasses, O. Topall, C. Jouany, M. Duru, P. Cruz

IGC Proceedings (1977-2023)

The objectives are to study the effects of N and P supply and their interaction, on herbage dry matter yield and nutrient status of three tropical grasses. In order to estimate direct and indirect effects of P supply we express above-ground dry matter production as a function of the herbage nutrient status obtained from plant analysis. Results show that in absence of N, the significant increase in P nutrition status has only moderate consequences on herbage production and suggest that both N and P are limitant for herbage growth. P fertilization results in significant increase in dry matter yield only …

Air Pressure Propagation Through Wind Cave And Jewel Cave: How Do Pressure Waves Travel Through Barometric Caves?, Annika K. Gomell, Daniel C. Austin, Marc J. Ohms, Andreas Pflitsch

International Journal of Speleology

In barometric caves, air pressure gradients between the outside atmosphere and the cave induce strong bidirectional compensating currents, which control almost all elements of speleoclimatology, including air temperature, humidity, and CO₂ dynamics. Therefore, this study set out to investigate air pressure propagation through Wind Cave and Jewel Cave – two major barometric cave systems in the Black Hills of South Dakota, USA. Based on high-resolution air pressure data from both the surface and several measurement sites inside the caves, four systematic changes of pressure waves during their journey through the caves and their related speleoclimatological processes were identified and …

Mineral Acquisition And Utilization Strategy Of Three Tropical Forages At Different Phosphorus And Nitrogen Supply, J. D. G. Santos Junior, Tsutomu Kanno, Manuel C. M. Macedo, M. R. Correa, L. G. Beretta

IGC Proceedings (1977-2023)

A glasshouse experiment was conducted to examine mineral acquisition and utilization strategies of Brachiaria decumbens (BD), Brachiaria brizantha (BB) and Panicum maximum (PM). The plants were grown under nine treatments resulted from the combination of three levels of phosphorus (0, 25 and 50 kgP/ha) and three levels of nitrogen (25, 150 and 300 kgN/ha). BD showed the lowest value of root weight and root length per pot, but the highest efficiency of P and N uptake (P and N uptake mg / unit root weight g). On the other hand, PM showed lower mineral uptake efficiency, but the highest mineral …

Sources And Rates Of Phosphorus In Improving Degraded Pasture In Brazilian West Amazon, Valdinei T. Paulino, N. L. Costa, C. R. Townsend, J. A. Magalhães, R. G. A. Periera

IGC Proceedings (1977-2023)

The effects of phosphorus sources (triple superphosphate – TSP, single superphosphate – SSP and partially acidulated rock phosphate – PARP) and rates (0, 50 and 100 kg/ha of P₂O₅ on dry matter (DM) yields and chemical composition of a degraded Brachiaria brizantha cv. Marandu pasture were evaluated in a cutting trial. Phosphorus fertilization, irrespective of sources and rates, showed an effective agronomic technique for pasture recuperation. The grass DM yields and potassium contents were significantly improved by phosphorus application, while weed DM yields were depressed. Irrespective of sources and rates, crude protein, phosphorus, and calcium contents were …

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Understanding Shoot And Root Development, C. Matthew, E. N. Van Loo, E. R. Thom, L. A. Dawson, D. A. Care

IGC Proceedings (1977-2023)

Shoot and root development of the grass tiller is presented as a series of events on the tiller axis. Leaf, tiller bud, true stem, and root development are successive events in the life cycle of a single phytomer and the tiller is a co-ordinated series of phytomers, successive phytomers being progressively more advanced than the previous phytomer. In reviewing the individual growth processes of leaf, tiller, true stem, and root formation, fundamental determinants of light and nutrient capture are examined and examples presented to illustrate the link between component processes, plant morphogenesis, and plant performance. An example of the application …

Ecophysiology Of Grasslands: Dynamic Aspects Of Forage Plant Populations In Grazed Swards, G. Lemaire

IGC Proceedings (1977-2023)

The aim of this paper is to review knowledge of the ecophysiological mechanisms influencing the dynamics of plant populations in grazed swards. Such an objective requires some definitions. Firstly, it is necessary to define “ecophysiology” as the study of the interactions between biological individuals (plants) with their own environment: how individuals perceive and react to any constraint and change of their environment, and how the functioning of plants as a population can modify their own environment. Such a definition implies a dynamic approach to pant population functioning as resulting from constant plant-plant interactions mediated by micro-environment modifications. In a grazed …

Bite Depth Penetration Patterns Of Dairy Cows Foraging On Complex Swards, W. M. Griffiths, J. Hodgson, G. C. Arnold

IGC Proceedings (1977-2023)

Sward height was the dominant cue used by dairy cattle to determine the depth of penetration on young vegetative swards. On more complex swards, bite depth penetration was controlled by variations in the depth of regrowth. Evidence showed that cattle grazed to the pseudostem:lamina interface, but sward height exerted a stronger effect on bite depth than pseudostem height. Modelling efforts to predict how the herbivore places bites in space in the vertical dimension across sward states are currently being restricted by the absence of detailed canopy structure descriptions. We argue that the contrast between strata is an important determinant of …

The Effect Of Progressive Grazing Of A Pasture On The Spatial Distribution Of Herbage Mass And Utilization By Cattle, Masahiko Hirata, S. Ogura

IGC Proceedings (1977-2023)

To develop an understanding of the spatially heterogeneous grazing of a pasture by large herbivores under progressive grazing, the herbage mass, herbage consumption and ingestive behavior by cattle were monitored daily at ninety-one 50 × 50 cm permanent locations in a bahiagrass (Paspalum notatum Flügge) pasture during a 6-day grazing period. With the progress of grazing, the mean pre-grazing herbage mass over the locations decreased. Responding to this, the mean number of visits and the mean rate of biting increased, and the mean residence time and the mean rate of defoliation decreased. The pre-grazing herbage mass became more heterogeneous, …

Nitrogen Response Efficiencies From Grazed Dairy Pastures Under Dry Conditions, Frank R. Mckenzie, Joseph L. Jacobs

IGC Proceedings (1977-2023)

Experiments were conducted within a long-term nitrogen (N) fertiliser experiment under grazing. The objective was to examine N response efficiencies (kg dry matter (DM)/kg N) and herbage crude protein (CP) content to fertiliser N applied under dry soil conditions (gravimetric soil moisture content of 17% at 10cm; soil field capacity = 38% and wilting point = 11%) during autumn (April 1999) and late spring (November 1999) in southeastern Australia. Visually, N treated plots were greener in colour than control (no N) plots. No differences were recorded in primary or residual DM yields, N response efficiencies, and pasture growth rates between …