Agriculture has traditionally an important role in Hungarian economy and rural development. About 70 % of Hungary's total territory is under agricultural land use, and 50 % is the arable land. Hungarian crop production is cereal oriented (65-68 % of arable land) because of agroecological conditions, production traditions, market-utilization and demand. Our long-term, small plots experiments were to study the effects of agroecological conditions (cropyears, soils), the aspects of variety-selection (genetic-pool testing) and fertilization on the yield, yield-stability and quality of wheat production. In sustainable, agronomically and economically effective crop production it is basically important to harmonize the agroecological, biological and agrotechnical elements. From agronomic, economic and environmental aspects the fertilization (mainly nitrogen) is the decisive, key-element in crop management. In long-term experiment we were studying the effect of different nitrogen fertilizer doses on the NO3-N content and distribution in the chernozem soil of Trans-Tisza (eastern part of Hungary) under continental meteorological conditions. The test crop was winter wheat. The soil samples were taken up after the harvest of winter wheat in 1995 (0-200 cm soil layers), 1998 (0-200 cm) and 2000 (0-300 cm). Our research results proved that the NO3-N content strongly increased if we used N-fertilizer doses over the optimum dose (over N120+PK) of winter wheat (the maximum NO3-N contents were 110 mg kg-1, 125 mg kg-1 and 275 mg kg-1 in 1995, 1998, 2000, respectively). According to our scientific results we can state that the accumulation zone of NO3-N slightly moved into the deeper soil layers (the accumulation zone was in 100-120 cm in 1995, in 140-160 cm in 1998, in 160 cm in 2000, respectively). In our long-term experiment the optimum N-dose (+PK) varied depending on the cropyear (water supply in vegetation period and winter period too) and genotypes (variety-specific fertilization). The optimum N-doses ranged 60-120 kgha-1 (+PK) depending on years and variety. Over the optimum N-dose some NO3-N residues remained in the soil which accumulated year by year. The appropriate fertilization could effectively modify not only the yield quantity but quality as well. Our long-term experimental results proved that the fertilization (mainly N and harmonized PK) could strongly increase the wet gluten content and averagely the farinograph indexes and slightly the falling number. Our result proved that the changes of quality parameters were variety-specific.