Effects of four cultivation systems for maize on nitrogen leaching .1. Field experiment

`An experiment was conducted for 3 years on the Venetian Plain (northeast Italy) to evaluate the environmental impact of four cropping systems at different input levels. The four systems were: (A) higher inputs with pesticides, chemical fertilizers and liquid manure; (B) higher inputs with pesticides and chemical fertilizers; (C) lower inputs with low doses of fertilizers, post-emergence herbicides and use of cover crops; (D) organic, with low inputs without artificial fertilizers or pesticides. To assess the environmental impact samples of groundwater, soil and crop were taken from one field in each system, cultivated with maize but subjected to various management strategies. The results showed large differences in the nitrate nitrogen (NO3-N) concentration in the shallow groundwater, ranging from a mean value of 7.89 mg 1(-1) in system A to 2.21 mg 1(-1) in system C. Less variability was observed for total Kjeldhal nitrogen (TKN): a maximum of 5.69 mg 1(-1) for system D and a minimum of 2.74 mg 1(-1) for system B. Total annual nitrogen losses (TKN+N-NO3) were 48, 19, 16 and 15 kg ha(-1) year(-1) in the four cultivation systems, respectively. (C) 1997 Elsevier Science B.V.