Critical nitrogen and potassium dilution curves for potato in Northeast China

Abstract

Context or problem

Excessive nitrogen (N) application and insufficient potassium (K) inputs are prevalent in potato production across Northeast China, leading to nutrient imbalances that limit yield potential and reduce nutrient use efficiency. This underscores the need for robust diagnostic models to support site-specific nutrient management.

Objectives

This study aimed to (i) develop universal critical N and K dilution curves (CNDC and CKDC) for potato based on whole-plant biomass, with parameters uncertainty assessed across years and cultivars; and (ii) evaluate the relationship between tuber yield and N/K nutrition indices (NNI and KNI).

Methods

Field trials were conducted over three years in Heilongjiang Province, involving four predominant potato cultivars under varying N and K treatments. A Bayesian framework was employed to develop CNDC and CKDC models and quantify parameter distributions across genotype × environment × management (G×E × M) scenarios.

Results

The parameters of CNDC and CKDC models did not differ significantly across cultivars and years. The final models were defined as Nc = 4.91 W^−0.44 and Kc = 5.76 W^−0.35. Both NNI and KNI demonstrated strong quadratic relationships with relative tuber yield (R² = 0.82–0.99) across most cultivars, though curve shapes varied. Maximum yield was typically associated with NNI values of 0.84–1.31 and KNI values of 0.96–1.09.

Conclusions and Implications

The CNDC and CKDC models provide highly reliable, physiology-based tools for potato nutrient diagnosis. Specifically, recommended application rates are 140 kg N ha⁻¹ and 230 kg K ha⁻¹, enabling precision nutrient management and promoting sustainable potato production.