Nitrogen gross balance in farms specialised in plant production in selected regions of Poland

The aim of the performed investigations was to evaluate nitrogen management in farms specialising in plant production situated in the following voivodeships: Wielkopolskie, Dolnośląskie, Opolskie and Mazowieckie. The analysed data were derived from 31 individual farms specialising in plant production situated in various regions and covered the period of 2004–2006. Farms from Wielkopolska and Dolny Śląsk were situated in nitrate vulnerable zones (NVZ’s). The nitrogen balance in farms located in NVZ’s, on average, amounted to 12.5 kg N ha-1 of agricultural land (AL). In the case of farms situated in Opolskie voivodeship, a significant deficit of this element was observed amounting to -63.3 kg N ha-1 of AL. Farmers from Raszyn commune in Mazowieckie voivodeship posed a potential hazard to the environment managing nitrogen resources in an irrational way. The nitrogen balance there exceeded the Code of Good Agricultural Practice (COGAP) recommended standard of 30 kg N ha-1 of AL reaching the level of about 50 kg N ha-1 of AL.