Objectives Maize production is characterized by high yield and intensive fertilizer input, requires scientific fertilizer recommendation for high yield as well as fertilizer use efficiency and profit. We constructed an intelligent fertilizer recommendation method for maize based on large number of yield response and agronomic efficiency data, and carried out field experiments to calibrate and verify the availability of the recommendation.

Methods The data were collected by searching key worlds/phrases “maize”, “maize + yield”, “maize + nutrient uptake”, and “maize + fertilizer use efficiency” from the multi-year/point maize field fertilizer experiments,including those supported by International Plant Nutrient Institute (IPNI) China Program, carried out by our research group, and published in the relevant articles. The QUEFTS model was used to analyze the nutrient uptake characteristics, yield response under optimized fertilization, fertilizer agronomic efficiency, and the intrinsic relationships among the indices, to build the Nutrient Expert (NE) system for maize. Totally 803 field experiments were conducted in the maize producing areas around China from 2010 to 2019 to validate and calibrate the precision of the NE system. All the field experiment composed of six fertilization treatments: recommendation based on NE (NE), farmers’ practices (FP), conventional recommendation based on soil testing (ST), and omission N, omission P and omission K treatments based on NE. Fertilizer application rate, maize yield, economic benefit, fertilizer use efficiency were investigated.

Results Based on QUEFTS model analysis, the aboveground N, P and K nutrient requirements to produce 1 ton of grain yield were 15.9, 4.1 and 13.8 kg for spring maize and 17.8, 4.0 and 15.8 kg for summer maize, respectively. The average yield responses to N, P and K fertilizer were 2.9, 1.5 and 1.4 t/hm² for spring maize and 1.9, 1.1 and 1.1 t/hm² for summer maize. The agronomic efficiencies of N, P and K fertilizer were 15.0, 18.9 and 16.1 kg/kg for spring maize and 10.8, 16.8 and 12.3 kg/kg for summer maize, respectively. The soil N, P and K contribution to yield reached 73%, 86% and 87% for spring maize, and 79%, 87% and 88% for summer maize, respectively. The field validation results showed that, the NE treatment applied 29.3% and 14.3% less N fertilizer, 17.3% and 7.5% less P fertilizer than FP and ST treatments, but increased yield by 0.4 and 0.1 t/hm², net profit by 797 and 354 yuan/hm², N recovery use efficiency by 10.6 and 3.8 percentage points, and agronomic efficiency by 4.6 and 2.0 kg/kg; increased P recovery use efficiency by 8.0 and 3.1 percentage points, and agronomic efficiency by 6.5 and 1.5 kg/kg; increased K recovery use efficiency by 9.6 and 3.4 percentage points, and agronomic efficiency by 0.8 and 0.3 kg/kg, respectively.

Conclusions The Nutrient Expert for maize exhibited obviously higher fertilizer reduction and benefit enhancement effect than the conventional soil testing recommendation method, indicating its operability and availability as a simple and precise fertilizer recommendation method in maize production around China.