Nitrogen discharge pathways in vegetable production as non-point sources of pollution and measures to control it

Discharge of nitrogen (N) fromfertilizers applied to vegetables is becoming a serious environmental problem. In a field experiment involving a celery-tomato-fallow-lettuce rotation, leachingwas the primary pathway of N loss (56.1 +/- 0.4% of the total), followed, in descending order, by runoff (11.7 +/- 0.3%), N(2)Oemissions (1.6 +/- 0.1%), and volatilization of ammonia (0.5 +/- 0.1%). Decreasing the traditional dose of N by 40% in each growth season decreased N leaching by 22.3 +/- 4.5, 39.8 +/- 6.7, 40.3 +/- 2.9 and 27.4 +/- 3.6% in celery, tomato, fallowand lettuce seasons, respectively, without any yield loss, andmodifying the rotation to include a leguminous crop reduced the N leaching by 72 +/- 2, 40 +/- 3, 24 +/- 2 and 13 +/- 1% in each season, respectively, without any economic impact. These measures decreased annual N leaching by 36 +/- 4%. A combination of the eco-ditches and wetland paddy fields adjacent to the vegetable plot led to annual N removal efficiency of 73 +/- 6% in runoff. (C) 2017 Elsevier B.V.All rights reserved.