Effect of Nitrogen and Irrigation Application on Water Movement and Nitrogen Transport for a Wheat Crop under Drip Irrigation in the North China Plain

For improving water scarcity and groundwater pollution from agriculture, two-year experiments (2011–2013) with three water levels (0.3, 0.5 and 0.8 evaporation (E) in 20-cm-diameter pans) and four nitrogen (N) levels (120, 140 and 190 kg·ha−1 in 2012 and 120, 190 and 290 kg·ha−1 in 2013) were conducted to study effects of water and N availability on water movement and N transport for a wheat crop under drip irrigation in the North China Plain. The results indicated that under drip irrigation, deep percolation at 1-m depth was stable at 0.5–0.8 E with the same N rate for winter wheat. At 0.5–0.8 E, deep percolation was also relatively stable with increasing N rate from 120 to 140 kg·ha−1 or from 190 to 290 kg·ha−1. The irrigation schedule and N rates only affected N leaching below the root zone of winter wheat (60-cm depth), while the N residual in the soil layer presented more risk to the environment than N leaching. In general, the 290-kg-ha−1 N level was not recommended using drip fertigation for winter wheat in the North China Plain. The empirical equation given by the Ministry of Geology and Mineral Resources was also not recommended for estimating the drainage under drip irrigation. OPEN ACCESS