Growth and nitrogen productivity of drip-irrigated winter wheat under different nitrogen fertigation strategies in the North China Plain

Abstract

Excessive application of nitrogen (N) fertilizer is the main cause of N loss and poor use efficiency in winter wheat ( Triticum aestivum L.) production in the North China Plain (NCP). Drip fertigation is considered to be an effective method for improving N use efficiency and reducing losses, while the performance of drip fertigation in winter wheat is limited by poor N scheduling. A two-year field experiment was conducted to evaluate the growth, development and yield of drip-fertigated winter wheat under different split urea (46% N, 240 kg ha −1 ) applications. The six treatments consisted of five fertigation N application scheduling programs and one slow-release fertilizer (SRF) application. The five N scheduling treatments were N0-100 (0% at sowing and 100% at jointing/booting), N25-75 (25% at sowing and 75% at jointing/booting), N50-50 (50% at sowing and 50% at jointing/booting), N75-25 (75% at sowing and 25 at jointing/booting), and N100-0 (100% at sowing and 0% at jointing/booting). The SRF (43% N, 240 kg ha −1 ) was only used as fertilizer at sowing. Split N application significantly ( P <0.05) affected wheat grain yield, yield components, aboveground biomass (ABM), water use efficiency (WUE) and nitrogen partial factor productivity (NPFP). The N50-50 and SRF treatments respectively had the highest yield (8.84 and 8.85 tons ha −1 ), ABM (20.67 and 20.83 tons ha −1 ), WUE (2.28 and 2.17 kg m −3 ) and NPFP (36.82 and 36.88 kg kg −1 ). This work provided substantial evidence that urea-N applied in equal splits between basal and topdressing doses compete economically with the highly expensive SRF for fertilization of winter wheat crops. Although the single-dose SRF could reduce labor costs involved with the traditional method of manual spreading, the drip fertigation system used in this study with the N50-50 treatment provides an option for farmers to maintain wheat production in the NCP.