Nitrogen fertiliser replacement values for organic amendments appear to increase with N application rates

Nitrogen (N) supply from organic amendments [such as farmyard manure (FYM), slurries or crop residues] to crops is commonly expressed in the amendment’s Nitrogen Fertiliser Replacement Value (NFRV). Values for NFRV can be determined by comparison of crop yield or N uptake in amended plots against mineral fertiliser-only plots. NFRV is then defined as the amount of mineral fertiliser N saved when using organic amendment-N (kg/kg), while attaining the same crop yield. Factors known to affect NFRV are crop type cultivated, soil type, manuring history and method or time of application. We investigated whether long-term NFRV depends on N application rates. Using data from eight long term experiments in Europe, values of NFRV at low total N supply were compared with values of NFRV at high total N supply. Our findings show that FYM has a significant higher NFRV value at high total N supply than at low total N supply (1.12 vs. 0.53, p = 0.04). For the other amendment types investigated, NFRV was also higher at high total N supply than at low total N supply, but sample sizes were too small or variations too large to detect significant differences. Farmers in Europe usually operate at high rates of total N applied. If fertiliser supplements are based on NFRV of the manure estimated at low total N supply, N fertiliser requirements might be overestimated. This might lead to overuse of N, lower N use efficiency and larger losses of N to the environment

Imaging properties of different optics for EUV radiation

Triggered by the roadmap of the semiconductor industry, tremendous progress has been achieved in the development of Extreme Ultraviolet (EUV) sources and high-quality EUV optical coatings in recent years, opening up also new fields of applications apart from microlithography, such as metrology, high-resolution microscopy, or surface analysis. In all these research areas the quality and imaging properties of the employed optics play a crucial role. In this contribution we present a comparison of different optical setups capable of guiding and imaging EUV radiation, which were tested in combination with a miniaturized laser-produced plasma source with high pulse energy (~ 3.5 mJ @ 13.5 nm) and a plasma size of about 300 µm. First, a modified EUV Schwarzschild objective with a numerical aperture of 0.44 and a demagnification factor of 10 was developed within the research project "KOMPASS". After adaptation to the table-top EUV source, a focus with a diameter < 30 µm at energy densities of several mJ/cm2 could be produced. The setup is currently being used for comparative investigations of the interaction of EUV radiation with different materials, as e.g. the color center formation in LiF crystals. An attempt to use the Schwarzschild objective in reverse geometry as a EUV microscope will be part of future work. Second, a Kirkpatrick-Baez arrangement was realized, using the reflections from two curved silicon wafers under grazing incidence (about 5°). The cylindrical curvature is obtained by bending the thin substrates, allowing for a continuous tuning to the desired radii. Due to an Au coating a high reflectivity (theoretically ~ 80 % per reflection) over a broad EUV spectral range can be achieved. For reduction of aberrations the optical systems were fine-adjusted with the help of a Hartmann-Shack wavefront sensor both in the visible and in the EUV spectral range. The imaging properties in the EUV range were determined and compared to ray tracing calculations performed with ZEMAX

Time-resolved NEXAFS-Spectroscopy on Photoinduced Phase Changes using a Table-top XUV Spectrometer

We present a table-top soft-x-ray spectrometer for the wavelength range λ = 1–5 nm based on a stable laser-driven x-ray source, making use of a gas-puff target. With this setup, optical light-pump/soft-x-ray probe near-edge x-ray absorption fine structure(NEXAFS) experiments with a temporal resolution of about 230 ps are feasible. Pump-probe NEXAFSmeasurements were carried out in the “water-window” region (2.28 nm–4.36 nm) on the manganite Pr$_{0.7}$Ca$_{0.3}$MnO$_3$, investigating diminutive changes of the oxygen K edge that derive from an optically induced phase transition. The results show the practicability of the table-top soft-x-ray spectrometer on demanding investigations so far exclusively conducted at synchrotron radiation source