Effects of Nitrogen Fertilization on Nitrate Transformation and Accumulation in Greenhouse Vegetable Fields

A field experiment was conducted under protected cultivation condition to examine the effects of reduced N fertilizer and combined with the inhibitors on the accumulation of NO3——N in soil during the growing stages of cucumber plantation.Results showed that reduction of N fertilization could significantly decreased NO3——N content of surface soil and other layers of the soil profile.Nitrate contents in 0-40 cm soil layers were greater under the conventional N application than in the other treatments.As N input was reduced by 30%,NO3——N accumulation was not significant in 0-40 cm soil layers.Nitrogen fertilizer combined with inhibitor could decrease the content and leaching loss of NO3——N,of which the effect of NBPT combined with DCD treatment on NO3——N accumulation was the best.Nitrogen fertilization combined with inhibitors could effectively control the over-accumulation of nitrate in both soil and test vegetable,and reduce the leaching loss of NO3——N.