The most important prerequisite for a successful mushroom production is a high-quality compost substrate. For the present study wheat straw was used as bulk ingredient for the compost substrate preparation. In order to improve the C/N ratio and to accelerate the composting process, all substrate formulas need the addition of nitrogen-rich supplements at the outset of composting. Besides organic nitrogen sources, inorganic nitrogen supplements are also applied, when high-carbohydrate bulk ingredients are used. In the present work four different nitrogen fertilizers (urea (46 % N), ammonium nitrate (33.5 % N), calcium ammonium nitrate (26 % N) and ammonium sulfate (21 % N)) in three doses were applied as nitrogen sources and the effect on yield and some quality characteristics (cap weight, stalk weight, cap diameter, stalk diameter and stalk length) was investigated. The fertilizer application had only an unimportant effect on the cape diameter, which is an important characteristic for the classification of mushrooms, but had a stronger effect on the stalk length, which is also important for the classification. The highest dose of calcium ammonium nitrate produced the significant highest yield at the same time this variant also resulted in good results regarding the investigated quality characteristics.