N, P and K budgets for crop rotations on nine organic farms in the UK

On organic farms, where the importation of materials to build/maintain soil fertility is restricted, it is important that a balance between inputs and outputs of nutrients is achieved to ensure both short-term productivity and long-term sustainability. This paper considers different approaches to nutrient budgeting on organic farms and evaluates the sources of bias in the measurements and/or estimates of the nutrient inputs and outputs. The paper collates 88 nutrient budgets compiled at the farm scale in 9 temperate countries. All the nitrogen (N) budgets showed an N surplus (average 83.2 kg N ha-1 year-1). The efficiency of N use, defined as outputs/inputs, was highest (0.9) and lowest (0.2) in arable and beef systems respectively. The phosphorus (P) and potassium (K) budgets showed both surpluses and deficits (average 3.6 kg P ha-1 year-1, 14.2 kg K ha-1 year-1) with horticultural systems showing large surpluses resulting from purchased manure. The estimation of N fixation and quantities of nutrients in purchased manures may introduce significant errors in nutrient budgets. Overall, the data illustrate the diversity of management systems in place on organic farms, and suggest that used together with soil analysis, nutrient budgets are a useful tool for improving the long-term sustainability of organic systems

Magnetothemopower study of quasi two-dimensional organic conductor α\alpha-(BEDT-TTF)2_2KHg(SCN)4_4

We have used a low-frequency magneto-thermopower (MTEP) method to probe the high magnetic field ground state behavior of $\alpha$-(BEDT-TTF)$_2$KHg(SCN)$_4$ along all three principal crystallographic axes at low temperatures. The thermopower tensor coefficients ($S_{xx}, S_{yx}$ and $S_{zz}$) have been measured to 30 T, beyond the anomalous low temperature, field-induced transition at 22.5 T. We find a significant anisotropy in the MTEP signal, and also observe large quantum oscillations associated with the de Haas - van Alphen effect. The anisotropy indicates that the ground state properties are clearly driven by mechanisms that occur along specific directions for the in-plane electronic structure. Both transverse and longitudinal magnetothermopower show asymptotic behavior in field, which can be explained in terms of magnetic breakdown of compensated closed orbits.Comment: 9 pages, 10 figure

First observation of the ( 4 He, 8 B) reaction

The ( 4 He, 8 B) reaction on 27 Al and 66 Zn targets has been studied at E α =109MeV, the first observation of this reaction. Five groups appear in the first 4 MeV of excitation in the 23 Ne spectrum, with laboratory differential cross sections ranging from 35 to 384 nb/sr at θ lab =8 0 . Individual levels in 62 Co were not resolved in the exposure on the 66 Zn target. However, 8 B events were observed which are tentatively attributed to the 66 Zn(α, 8 B) 62 Co reaction, since contributions from plausible target contaminants can be eliminated on the basis of Q value. The observed yield at 8 0 indicates a laboratory cross section of 540 nb/sr summed over the first 4.6 MeV of excitation in 62 Co.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45824/1/10050_2005_Article_BF01547474.pd

Coherent π0 photoproduction on the deuteron up to 4 GeV

The differential cross section for 2H(γ,d)π0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions

Measurements of Deuteron Photodisintegration up to 4.0 GeV

The first measurements of the differential cross section for the d(γ,p)n reaction up to 4.0 GeV were performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson Laboratory. We report the cross sections at the proton center-of-mass angles of 36°, 52°, 69°, and 89°. These results are in reasonable agreement with previous measurements at lower energy. The 89° and 69° data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 52° and 36° data disagree with the counting-rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data.U.S. Department of Energy, National Science Foundatio