Responsible for the merit-based scholarship is the Study services of BOKU. The requirements of the scholarship are changing from year to year. There is no legal claim on the scholarship! You can find further information for the new application round always at the end of August here: http://www.boku.ac.at/studienservices/themen/stipendien/leistungsstipendium/ (German only)
To get an idea how the requirements will look like, here are the official application requirements from 2016/17 and 2017/18:
Ausschreibung Leistungsstipendium 2016/17 (German only)
Ausschreibung Leistungsstipendium 2017/18 (German only)
Need-based scholarships are intended for students who require financial assistance while writing their thesis. For example, a student writing a thesis on avalanches in Tyrol would be able to apply for a need-based scholarship in order to travel there for research purposes. Need-based scholarships are only awarded if proposed research meets eligibility criteria.
The criteria for awarding need-based scholarships are essentially the same as for merit-based scholarships. Every university has a certain budget allocated for this purpose. Applicants must demonstrate why certain scientific research is deserving of funding. Reasons may include high travel costs or extensive and costly research. These funds are provided by the Federal Ministry for Science and Research.