The Nutrient Expert decision support system improves nutrient use efficiency and environmental performance of radish in North China

Excessive fertilization has led to nutrient use inefficiency and serious environmental consequences for radish cultivation in North China.  The Nutrient Expert (NE) system is a science-based, site-specific fertilization decision support system, but the updated NE system for radish has rarely been evaluated.  This study aims to validate the feasibility of NE for radish fertilization management from agronomic, economic, and environmental perspectives.  A total of 46 field experiments were conducted over four seasons from April 2018 to November 2019 across the major radish growing regions in North China.  The results indicated that NE significantly reduced N, P₂O₅, and K₂O application rates by 98, 110, and 47 kg ha⁻¹ relative to those in the farmers’ practice (FP), respectively, and reduced N and P₂O₅ inputs by 48 and 44 kg ha⁻¹, respectively, while maintaining the same K₂O rate as soil testing (ST).  Relative to FP and ST, NE significantly increased radish yield by 2.7 and 2.6 t ha⁻¹ (4.2 and 4.0%) and net returns by 837 and 432 USD ha⁻¹, respectively.  On average, NE significantly improved the agronomic efficiency (AE) of N, P, and K (relative to FP and ST) by 42.4 and 31.0, 67.4 kg kg⁻¹ and 50.9, and 20.3 and 12.3 kg kg⁻¹; enhanced the recovery efficiency (RE) of N, P, and K by 11.4 and 7.0, 14.1 and 7.5, and 11.3 and 6.3 percentage points; and increased the partial factor productivity (PFP) of N, P, and K by 162.9 and 96.8, 488.0 and 327.3, and 86.9 and 22.4 kg kg⁻¹, respectively.  Furthermore, NE substantially reduced N and P₂O₅ surpluses by 105.1 and 115.1 kg ha⁻¹, respectively, and decreased apparent N loss by 110.8 kg ha⁻¹ compared to FP.  These results indicated that the NE system is an effective and feasible approach for improving NUE and promoting cleaner radish production in North China.