Assessment of productivity and profitability of sole and double-cropping for agricultural biomass production

Zweifruchtsysteme werden in Deutschland als alterna­tive Anbausysteme für die landwirtschaftliche Biomasse­produktion erwogen. In dieser Untersuchung wurden die Produktivität und Wirtschaftlichkeit von Zweifruchtnutzung und Hauptfruchtanbau in den Jahren 2007 bis 2009 an drei klimatisch unterschiedlichen Standorten in Deutschland verglichen. Die wärmeliebenden Kulturen Mais (Zea mays L.), Futterhirse [Sorghum bicolor (L.) Moench] und Sudangras [S. bicolor (L.) Moench × S. sudanense (Piper) Stapf] wurden entweder allein als Hauptfrüchte oder als Zweitfrüchte nach Winterroggen (Secale cereale L.) angebaut. Bei Zweifruchtnutzung wurde der Winterroggen entweder zwischen Anfang und Mitte Mai (früh) oder Anfang Juni (spät) geerntet. Während der Winterroggen kein Zusatzwasser erhielt, wurden Mais, Futterhirse und Sudangras sowohl mit als auch ohne künstliche Bewässerung angebaut. Der Winterroggen lieferte einen oberirdischen Trockenmasseertrag von 5,2 t ha–1 bei früher Ernte und von 9,0 t ha–1 bei später Ernte. Die ertragreichste Zweifruchtnutzung (Roggen-Mais) war der produktivsten Hauptfrucht (Mais) ohne Zusatzbewässerung um 3,6 t ha–1 (23%) und mit Zusatzbewässerung um 5,2 t ha–1 (24%) überlegen. Durch die Zusatzbewässerung erhöht sich der Trockenmasseertrag bei den Hauptfrüchten um 5,3 t ha–1 (37%), bei den früh gesäten Zweitfrüchten um 5,6 t ha–1 (43%) und bei den spät gesäten Zweitfrüchten um 6,8 t ha–1 (77%). Ohne Zusatzbewässerung wurden die, im Vergleich zum Hauptfruchtanbau, höheren Produktionskosten bei der Zwei­frucht­nutzung nicht durch entsprechend höhere Trocken­masseerträge kompensiert. Mit Zusatzbewässerung hingegen erzielte das Zweifruchtsystem Roggen-Mais an zwei von drei Versuchsstandorten höhere Deckungsbeiträge als der Hauptfruchtanbau von Mais.    Double-crop (DC) systems are receiving serious consideration as cropping alternative for agricultural biomass production in Germany. In this study the productivity and economics of DC and sole-crop (SC) systems were compared from 2007 to 2009 at three climatically diverse sites of Germany. The warm season crops maize (Zea mays L.), forage sorghum [Sorghum bicolor (L.) Moench] and sorghum-sudangrass [S. bicolor (L.) Moench × S. sudanense (Piper) Stapf] were either grown as sole crops or as second crop following winter rye (Secale cereale L.). The winter rye first crop was harvested premature at early-to-mid May (early) or early June (late). While the winter rye was grown under rainfed conditions, maize, forage sorghum, and sorghum-sudangrass were grown with or without irrigation. Winter rye produced an aboveground dry matter yield (DMY) of 5.2 t ha–1 at early harvest and 9.0 t ha–1 at late harvest. The highest yielding DC system (rye-maize) out-yielded the most productive SC system (maize) by 3.6 t ha–1 (23%) under rainfed conditions and by 5.2 t ha–1 (24%) with irrigation. Irrigation increased DMY of sole crops by 5.3 t ha–1 (37%), of early sown second crops by 5.6 t ha–1 (43%), and of late sown second crops by 6.8 t ha–1 (77%). Under rainfed conditions, the higher DMY of the DC as compared with the SC systems did not compensate the higher production costs. With irrigation, however, the rye-maize DC achieved higher contribution margins than SC maize at two of the three experimental sites.   &nbsp

Uptake of nitric acid in cirrus clouds and contrails

The uptake of nitric acid (HNO3) in cirrus clouds and contrails in the upper troposphere leads to a reduction of the gas phase NOx (=NO+NO2) concentration, resulting in a perturbation of the ozone budget within this region. During the CIRRUS-III campaign over Northern Germany in November 2006 aircraft-based measurements of gas- and condensed-phase reactive nitrogen species (NOy), water vapour, total water, and ice particle size distribution were performed to investigate the uptake of HNO3 in midlatitude cirrus clouds at altitudes between 8 and 12km. Contrails and cirrus clouds were frequently encountered in the course of this campaign. Contrails were identified by the detection of ice crystals in combination with enhanced gas phase NOy and condensation nuclei concentrations resulting from the aircraft exhaust. This method allows to unambiguously identify contrails and to separate contrails and natural cirrus clouds. The HNO3/H2O molar ratio in ice crystals and the particulate fraction of the total nitric acid (HNO3,part/HNO3,tot) were evaluated to quantify the uptake of nitric acid in ice clouds. We show the dependence of these two parameters on temperature, partial pressure of HNO3, and ice water content in the temperature range of 210 to 231K and at nitric acid partial pressures between about 1x10-8 and 1.2x10-7hPa. Further, we compare our data to previous observations in midlatitude clouds. Finally, differences in the chemical composition and trace gas uptake in natural and aviation-induced ice clouds are discussed

Elucidating the Role of Antisolvents on the Surface Chemistry and Optoelectronic Properties of CsPbBrxI3-x Perovskite Nanocrystals.

Funder: Cambridge Commonwealth, European and International TrustFunder: China Scholarship CouncilFunder: Solar Technologies go HybridFunder: University of CambridgeFunder: Royal Society of New ZealandColloidal lead-halide perovskite nanocrystals (LHP NCs) have emerged over the past decade as leading candidates for efficient next-generation optoelectronic devices, but their properties and performance critically depend on how they are purified. While antisolvents are widely used for purification, a detailed understanding of how the polarity of the antisolvent influences the surface chemistry and composition of the NCs is missing in the field. Here, we fill this knowledge gap by studying the surface chemistry of purified CsPbBrxI3-x NCs as the model system, which in itself is considered a promising candidate for pure-red light-emitting diodes and top-cells for tandem photovoltaics. Interestingly, we find that as the polarity of the antisolvent increases (from methyl acetate to acetone to butanol), there is a blueshift in the photoluminescence (PL) peak of the NCs along with a decrease in PL quantum yield (PLQY). Through transmission electron microscopy and X-ray photoemission spectroscopy measurements, we find that these changes in PL properties arise from antisolvent-induced iodide removal, which leads to a change in halide composition and, thus, the bandgap. Using detailed nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR) measurements along with density functional theory calculations, we propose that more polar antisolvents favor the detachment of the oleic acid and oleylamine ligands, which undergo amide condensation reactions, leading to the removal of iodide anions from the NC surface bound to these ligands. This work shows that careful selection of low-polarity antisolvents is a critical part of designing the synthesis of NCs to achieve high PLQYs with minimal defect-mediated phase segregation