After his return, he won a prize from the Royal Danish Academy of Sciences and Letters for his thesis about the ‘sand plants’ (mainly Marram grass) and their use as sand-binders in protection of agricultural lands from aeolian sand.[1] He was then appointed teacher (with the title of professor) at the Veterinary School (1787–1790). In 1796, the king sent Viborg to Poland and Romania to purchase stallions for the Frederiksborg stud farm. When the chair of botany was installed in 1797 at the University of Copenhagen, Viborg became its first holder, surpassing Martin Vahl.