Comparison of the nutrient diagnostic norm and optimum range of Ormosia hosiei based on DRIS and CND methods

Nutrient diagnosis is critical for improving fertilization efficiency and seedling quality in forest nursery production, yet reliable diagnostic criteria remain unavailable for valuable broad-leaved tree species. In this study, a “3414” nitrogen (N)–phosphorus (P)–potassium (K) fertilization experiment was conducted on two-year-old Ormosia hosiei seedlings cultivated in acidic yellow soil in southwestern China. The Diagnosis and Recommendation Integrated System (DRIS) and Compositional Nutrient Diagnosis (CND) methods were used to evaluate nutrient balance, identify limiting nutrients, and establish optimal nutrient ranges. Results showed that both approaches effectively characterized the nutritional status of O. hosiei seedlings, and chi-square tests confirmed that their diagnostic results were statistically reliable. However, CND exhibited stronger relationships with leaf nutrient concentrations and higher diagnostic accuracy, suggesting greater suitability for seedling nutrient assessment. The CND-derived optimal foliar nutrient ranges were 32.28–41.12 g kg −1 for N, 4.81–6.81 g kg −1 for P, 5.94–7.50 g kg −1 for K, 7.65–8.49 g kg −1 for Ca, 1.23–1.55 g kg −1 for Mg, 102.2–140.8 mg kg −1 for Fe, 3.75–8.35 mg kg −1 for Cu, and 11.45–19.81 mg kg −1 for Zn. Furthermore, due to nutrient fixation and ion antagonisms under acidic soil conditions, K, Mg, Cu, and Zn were identified as the most common limiting nutrients during the seedling stage. Among the tested fertilization regimes, T 3 (N 1 P 2 K 2 : 25 g N, 60 g P 2 O 5 , and 30 g K 2 O per plant) achieved the most favorable nutrient balance and promoted seedling growth without inducing micronutrient deficiencies. This study provides the first systematic comparison of the DRIS and CND methods for O. hosiei and establishes preliminary nutrient diagnostic standards, offering a scientific basis for precision fertilization and sustainable cultivation of this species, as well as a valuable reference for selecting forest tree nutrition diagnosis methods.