The feasibility of fertilising oats and forage sorghum with nitrogen and phosphorus in the Brigalow belt of Queensland: A modelling study

Annual forage crops such as oats and forage sorghum are sources of high-quality feed for mixed grain and beef enterprises in the northern region. However forage productivity declines over time as organic matter and subsequent supply of nutrients decrease with continued cultivation. The use of fertilisers to maintain production from oats and forage sorghum is common practice in higher rainfall and irrigated situations, however fertiliser use in generally drier and more variable environments such as the Brigalow belt is minimal despite declining productivity. We undertook a desktop, modelling assessment of the feasibility of fertilising these forages with nitrogen and phosphorus in the Brigalow belt in southern and central Queensland to better understand the dry matter and feed quality responses necessary to generate positive economic impacts. Results indicated significantly higher dry matter production is possible with fertiliser use, which can lead to higher animal liveweight gain and stocking rates. However under current market conditions the additional costs associated with applying fertiliser outweighed the extra benefits that can be generated. A combination of high dry-matter and animal production responses, lower costs associated with fertiliser application and positive price margins for the livestock grazing the forage are required to make fertiliser application consistently profitable. This modelling study demonstrates land-managers in the northern region need to carefully consider and monitor both the production and economic responses from trial areas before paddock scale applications are implemented

Possible production of exotic baryonia in relativistic heavy-ion collisions

Properties of a hypothetical baryonium with the quark content (uds\ov{u}\ov{d}\ov{s}) are discussed. The MIT bag model predicts its mass to be unexpectedly low, approximately 1210 MeV. Possible hadronic decay modes of this state are analyzed. Ultrarelativistic heavy-ion collisions provide favorable conditions for the formation of such particles from the baryon-free quark-gluon plasma. We estimate multiplicities of such exotic baryonia on the basis of a simple thermal model.Comment: 8 pages, 1 figur

alpha-nucleus potentials for the neutron-deficient p nuclei

alpha-nucleus potentials are one important ingredient for the understanding of the nucleosynthesis of heavy neutron-deficient p nuclei in the astrophysical gamma-process where these p nuclei are produced by a series of (gamma,n), (gamma,p), and (gamma,alpha) reactions. I present an improved alpha-nucleus potential at the astrophysically relevant sub-Coulomb energies which is derived from the analysis of alpha decay data and from a previously established systematic behavior of double-folding potentials.Comment: 6 pages, 3 figures, accepted for publication in Phys. Rev.

The S0_0(0) structure in highly compressed hydrogen and the orientational transition

A calculation of the rotational S$_0$(0) frequencies in high pressure solid para-hydrogen is performed. Convergence of the perturbative series at high density is demonstrated by the calculation of second and third order terms. The results of the theory are compared with the available experimental data to derive the density behaviour of structural parameters. In particular, a strong increase of the value of the lattice constant ratio $c/a$ and of the internuclear distance is determined. Also a decrease of the anisotropic intermolecular potential is observed which is attributed to charge transfer effects. The structural parameters determined at the phase transition may be used to calculate quantum properties of the rotationally ordered phase.Comment: accepted Europhysics Letter

Isomorphic classical molecular dynamics model for an excess electron in a supercritical fluid

Ring polymer molecular dynamics (RPMD) is used to directly simulate the dynamics of an excess electron in a supercritical fluid over a broad range of densities. The accuracy of the RPMD model is tested against numerically exact path integral statistics through the use of analytical continuation techniques. At low fluid densities, the RPMD model substantially underestimates the contribution of delocalized states to the dynamics of the excess electron. However, with increasing solvent density, the RPMD model improves, nearly satisfying analytical continuation constraints at densities approaching those of typical liquids. In the high density regime, quantum dispersion substantially decreases the self-diffusion of the solvated electron. In this regime where the dynamics of the electron is strongly coupled to the dynamics of the atoms in the fluid, trajectories that can reveal diffusive motion of the electron are long in comparison to $\beta\hbar$.Comment: 24 pages, 4 figure

Nitrogen fertiliser may pay on tropical grass pastures

Low productivity in sown grass pastures due to a lack of available soil nitrogen can reduce beef production by up to 50% across Queensland. The feasibility of strategic nitrogen (N) fertiliser applications to address these losses was assessed by desktop analyses using data from published studies, local fertiliser trials and expert opinion. These analyses suggest that applying nitrogen to rundown sown grass pastures can produce dramatic increases in dry matter yield and animal production. However, high and consistent response rates in pasture productivity, stocking rates and growth rate of cattle were required for the application of nitrogen fertiliser to be profitable. For the suggested 100 kg N/ha fertiliser rate: average gross margins in the year of application were calculated to increase by 121-217% when dry matter yield responses of 40 kg DM/kg N (i.e. an additional 4000 kg/ha) and an additional liveweight gain of 0.2 kg per adult equivalent (AE)/day can be achieved (i.e. an extra 70 kg AE/year). These economics were very sensitive to the assumed response rates in pasture growth, stocking rate and liveweight gain and did not account for uncertainty in climate and beef prices. New research is proposed to re-assess the responses used in this analysis that are largely based on research 25-40 years ago when soils were generally more fertile and pastures less rundown

Using Birdsfoot Trefoil in Kentucky Pastures

Birdsfoot trefoil (Lotus corniculatus L.) is an excellent pasture legume in the Corn Belt and in northeast United states . It has usually been considered too poorly adapted to Kentucky to merit trial by the farmers. Observations and grazing results in Woodford county during the last 14 years, however, indicate that this view is no longer valid. A grazing trial was established in 1954, with birdsfoot trefoil and Kentucky bluegrass as one of three mixtures used. Trefoil was seeded alone in the spring, and an excellent stand was obtained. Bluegrass was drilled in the established trefoil in September 1954. There were four 4-acre experimental pastures of trefoil-bluegrass and an additional 6-acre field which was used as a reserve pasture

Strength and Ultrasonic Characterization of Metallic Interfaces

In recent years, the process of diffusion bonding has found considerable usage in both the nuclear power and aerospace industries. This process requires the compression of mating surfaces at an elevated temperature for a given time. If optimum conditions of time, temperature, pressure and surface cleanliness are achieved, diffusion of material across the interface will occur, yielding interfacial mechanical properties identical to those of the bulk material. The use of insufficient bonding conditions may result in void formation, precipitation of undesired phases or lack of grain growth across the interface. The consequence will be an interface that is less than fully bonded, which will result in severe degradation of the mechanical properties. Applications of diffusion bonding to nuclear reactor fuel elements, helicopter rotor hubs, jet engine turbine blades, etc., thus make the ability to characterize the strength of these interfaces highly desirable

Bremsstrahlung in Alpha-Decay

We present the first fully quantum mechanical calculation of photon radiation accompanying charged particle decay from a barrier resonance. The soft-photon limit agrees with the classical results, but differences appear at next-to-leading-order. Under the conditions of alpha-decay of heavy nuclei, the main contribution to the photon emission stems from Coulomb acceleration and may be computed analytically. We find only a small contribution from the tunneling wave function under the barrier.Comment: 12 pages, 2 Postscript figure