The quantity and quality of organic carbon (Corg) input drive soil Corg stocks and thus fertility and climate mitigation potential of soils. To estimate fluxes of Corg as net primary production (NPP), exports, and inputs on German arable and grassland soils, we used field management data surveyed within the Agricultural Soil Inventory (n = 27.404 cases of sites multiplied by years). Further, we refined the concept of yield-based Corg allocation coefficients and delivered a new regionalized method applicable for agricultural soils in Central Europe. Mean total NPP calculated for arable and grassland soils was 6.9 ± 2.3 and 5.9 ± 2.9 Mg Corg ha−1 yr−1, respectively, of which approximately half was exported. On average, total Corg input calculated did not differ between arable (3.7 ± 1.8 Mg ha−1 yr−1) and grassland soils (3.7 ± 1.3 Mg ha−1 yr−1) but Corg sources were different: Grasslands received 1.4 times more Corg from root material than arable soils and we suggest that this difference in quality rather than quantity drives differences in soil Corg stocks between land use systems. On arable soils, side products were exported in 43% of the site * years. Cover crops were cultivated in 11% of site * years and contributed on average 3% of the mean annual total NPP. Across arable crops, total NPP drove Corg input (R2 = 0.47) stronger than organic fertilization (R2 = 0.11). Thus, maximizing plant growth enhances Corg input to soil. Our results are reliable estimates of management related Corg fluxes on agricultural soils in Germany.
Field experiments show that wheat grown after oilseed rape (OSR) achieves higher yield levels, while the nitrogen (N) application is reduced. However, field experiment data are based on few locations with optimised management. We analysed a large dataset based on farm data to assess the true extent of break crop benefits (BCB) for yield and N fertilisation within German commercial farming.Across all German states and years, average yield of wheat preceded by OSR was 0.56 Mg ha −1 higher than yield of wheat preceded by cereals (7.09 Mg ha −1 ), although considerable variation between regions was observed. Mean N application across all states to wheat after OSR was 5 kg ha −1 lower than to wheat after cereals. Choice of wheat types for different end uses (bread flour or animal feed) showed higher (0.77 Mg ha ) BCB for yield of wheat cultivated after OSR compared with after cereals. The calculated BCB for yield and N fertilisation were lower than expected from dedicated field experiments and fertiliser recommendations. Thus the advantages of OSR as a preceding crop are generally utilised by commercial farmers in Germany but there is room for improvement.
ARTICLE HISTORY
High Altitude Long Endurance (HALE) aircraft consist of extremely light-weight structures in combination with a high wingspan and high aspect ratio. The coupling of these properties results in a dynamic behavior of the aircraft system which is different to classical transport or unmanned aircraft configurations. The key finding in the analysis of the dynamic behavior of the aeroelastic HALE aircraft is a strong interaction of structural and rigid body eigenmodes. This leads to challenges in the design of a robust flight control algorithm for the full flight envelope with state-of-the-art techniques. This work addresses these difficulties and proposes a generic design process which can be used to develop flight control algorithms for HALE aircraft. The design process starts with the definition of specific performance and robustness criteria for HALE flight control laws which emerge from the combination of general aircraft design standards with the limitations and capabilities of the HALE configuration. Subsequently, a gain-scheduled, fixed structure control design architecture is proposed. The inner loop control design is enriched with envelope protection functionalities. The design process concludes with an extensive validation and verification process to clear the baseline flight control system for flight testing. The proposed design process is applied to the German Aerospace Center's newly developed HALE platform.
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