Nitrogen Utilization under Drip Irrigation with Sewage Effluent in the North China Plain

Field experiments were performed on maize ( Zea mays L.) to explore the impacts of water quality and nitrogen (N) application rate on soil N balance and nitrate leaching in the North China Plain. N application rates ranging from 0 to 180 kg ha −1 were tested, applying either secondary sewage effluent (SW) or groundwater (GW). Increasing the N application rate from 120 to 180 kg ha −1 did not significantly increase N uptake but substantially enhanced the apparent N loss (ANL) and nitrate leaching. Compared with GW irrigation, SW irrigation increased N uptake by 8% and soil residual N by 9% on average, whereas the ANL increased by 18%, suggesting that the detrimental impacts of SW irrigation may outweigh the benefits. The ANL values were enhanced mostly with increasing N application rates, followed by increasing initial soil N and nitrogen contained in irrigation water (irrigation N). Additionally, the ranking of factors increasing the leaching of nitrate was fertilizer N, deep percolation, irrigation N and initial soil N. Thus, SW irrigation combined with a high N application rate amplified the ANL and nitrate leaching losses. This study recommends N application rates ranging from 116 to 132 kg ha −1 to minimize the N losses when maize is irrigated with SW under drip irrigation in the North China Plain. Copyright © 2017 John Wiley & Sons, Ltd.