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The mineralization of soil organic nitrogen (N) and crop residues can significantly contribute to the N supply of vegetable crops. However, short-term mineralization dynamics are difficult to predict. On the other hand, fast-growing crops like spinach are highly sensitive to N shortage. Therefore, in situ soil columns have been tested to estimate the actual N supply via mineralization in field-grown spinach. In ten fertilization trials covered soil columns (20 cm in diameter) were driven into the soil to a depth of 30 cm at the start of the cultivation. Eight columns were repeated in three blocks within a total trial area of 0.10 to 0.25 ha. Net N mineralization was derived by subtracting the soil mineral N concentration (Nmin) in the upper 30 cm before installation from the concentration inside the columns at harvest. For comparison, a balance sheet was calculated for spinach plots receiving no N fertilization (zero plots) as well as fertilized plots and used as a proxy for net N mineralization. In this approach the initial Nmin concentration in the upper 30 cm of the soil, the N supply via irrigation, and fertilization as well as the total aboveground N uptake by spinach and the Nmin residue were considered. By using soil columns, N mineralization was determined with a mean coefficient of variation of 18%. A higher spatial variability of up to 43% was observed when spinach was grown as a second crop. The average net N mineralization rate ranged between 2 kg ha‑1 week‑1 (0-30 cm) in winter-grown spinach and 3-7 kg ha‑1 week‑1 (0-30 cm) in the other seasons. Nitrogen mineralization measured by the soil columns was qualitatively confirmed with the data obtained by the balance sheet. Soil columns enable repeated samplings during the spinach cultivation. In this way, top dressing rates can be adjusted to the actual N supply.
Spinach is a nitrogen (N)-demanding crop characterized by a shallow root architecture. Especially in the first weeks after sowing, significant N uptake is limited to the uppermost few centimetres of the soil. However, base fertilization is usually based on the soil mineral N (Nmin) concentration in the upper 30 cm. Therefore, the objective of this study was to examine whether the soil sample depth for calculating the base N fertilization can be reduced to the 0-15 cm layer. In seven field trials, conducted during spring, summer and autumn seasons, either a low or high base fertilization dose was applied at sowing. Until top dressing, soil samples were frequently taken in the upper 0-15 and 15-30 cm layers to determine the average Nmin concentration in each layer. Top dressing was applied when the first true leaves had unfurled. With this fertilizer application, the total N supply was aligned between both treatments based on the Nmin concentration in the upper 30 cm of the soil. Aboveground fresh and dry masses were determined after reaching a fresh mass yield of 15-20 t ha‑1 and related to the mean Nmin concentration in the first 3 to 4 weeks of cultivation between sowing and top dressing. It was shown that the Nmin concentration in the upper 0-15 cm of the soil highly reflects the base fertilization rate. By contrast, the Nmin concentration in the 15-30 cm layer remained unaffected. However, the Nmin concentration of both top soil layers can affect fresh and dry mass yield at harvest. Therefore, the entire 0-30 cm soil layer should be considered when calculating the base N fertilization rate in field-grown spinach. Measurements revealed that spinach fresh and dry masses were increased until the N availability of between 54 and 59 kg ha‑1 (0-30 cm) was reached at the seedlings stage, respectively.
Dieses Kapitel behandelt Marktforschungsansätze zur Wirkungsanalyse unternehmerischer Nachhaltigkeitshandlungen auf Endverbrauchermärkten. Ziel ist ein Überblick über Methoden, die aufgrund moderater Budgetvoraussetzungen in KMU und der angewandten Wissenschaft eingesetzt werden können. Dabei werden Herausforderungen der Messung ökologischer, sozialer und ethischer Kaufeigenschaften besonders berücksichtigt.
Die planungsrechtliche Zulässigkeit von Betrieben der Urbanen Produktion unterscheidet sich je nach ihrem Störgrad deutlich zwischen den Baugebietstypen der Baunutzungsverordnung (BauNVO). Während Betriebe, die das Wohnen nicht wesentlichen stören, auch in gemischten Baugebieten zulässig sind, kommen für Betriebe mit höheren Störgraden nur Gewerbe- und ggf. auch Industriegebiete infrage. Über die Ausweisung von Gewerbegebieten kann jedoch innerhalb eines Quartiers eine grobkörnige Nutzungsmischung erreicht werden. Betriebe, die das Wohnen nicht wesentlich stören, können über die Ausweisung gemischter Baugebiete wie dem Urbanen Gebiet zusätzlich in einer feinkörnigen Nutzungsmischung realisiert werden. Dabei kann die Verdrängung von Betrieben der Urbanen Produktion durch zahlungskräftigere Nutzungen mithilfe des Planungsrechts nur begrenzt beeinflusst werden. Insbesondere in Urbanen Gebieten besteht die Gefahr, dass sie von anderen Nutzungen wie dem Wohnen verdrängt werden.
This research project focused on the consumers' acceptance of a newly developed apple in order to encourage the purchase behavior in the supermarket. It was enriched with selenium via biofortification in order to address the undersupply with the trace element in the German population. The study included online surveys and a market test in food retail. The results were used as preparation for the design of a marketable apple product. In the online pretest, the most popular apple cultivars, the most popular health benefits of selenium, as well as the respondents' preferences for the name of the new apple: Selstar® were detected. These results were included in an online survey which encompassed n=1042 interviews from German households. The sample was recruited according to national representative distribution of age groups, gender, and regions. The results show that the majority of the respondents were not sure what exactly selenium is and what it is used or needed for. Therefore, the product package included information about the health benefits of selenium, for e.g. the immune system. The stepwise approach of the research and the implementation of the results helped the targeted navigation of the market launch of the Selstar®.
Maniok und Tapioka
(2021)