Abstract

Improper nitrogen (N) applications are threatening the sustainability of intensive agriculture in the North China Plain (NCP). Improved N management strategies are urgently needed to improve N use efficiency (NUE) and reduce the risk of environmental pollution. Many recently developed N management strategies have been successful in improving NUE and reducing N losses while achieving similar grain yield as farmer's practice. The objective of this study was to evaluate different nitrogen management strategies for potential application in NCP. A field experiment was conducted from 2008 to 2012 at Quzhou Experiment Station of China Agricultural University in Hebei Province. This experiment adopted randomized complete block design with 4 replications. The treatments included: (i) check with no N fertilizer (CK), (ii) soil mineral N (N_min) test-based in-season root-zoon N management strategy (IRNM-soil N_min), (iii) GreenSeeker-based precision N management strategy (PNM-GS), (iv) green window-based in-season N management strategy (INM-GW), (v) regional optimum N management strategy (RONM), and (vi) farmer's practice (FP). The average N fertilizer rate determined with IRNM-soil N_min, PNM-GS, INM-GW and RONM were 55%, 38%, 49% and 60% of the rate with FP, respectively, without significant reduction in grain yield.  As a result, the IRNM-soil N_min, PNM-GS, INM-GW and RONM increased the partial factor productivity over FP by 19%, 42%, 28% and 17%, respectively. In conclusion, the PNM-GS has the best potential to improve NUE in the NCP. Future studies are needed to integrate this strategy into high yield crop management systems to achieve both high yield and high NUE simultaneously for food security and sustainable development.

Keywords Precision nitrogen management; In-season nitrogen management; GreenSeeker sensor; Soil N_min test; Nitrogen use efficiency