By "designated crops" we refer to agricultural and forestry products which are not grown for the production of food and feed, but specifically for energetic (energy crops) or material (industrial crops) uses. In many publications, the term "designated crops" only refers to agricultural products. If you work with figures on the cultivation and use of designated crops, do investigate whether forestry products have also been included.
Since 1990, the energetic use of biomass has increased strongly in Germany. As can be seen from the figure below, designated crops are currently cultivated in Germany on about 2.45 million ha or 16% of the agricultural land. Of these, about 90% are energy crops, which are mainly used for biogas and fuel production. (Fachagentur Nachwachsende Rohstoffe e. V.) (FNR) 2019)
The most frequent crops cultivated in Germany for material and energy uses (as of 2016) are shown in the figure below.