The growth cycle of maize is relatively long, and its demand for nutrients such as nitrogen, phosphorus, and potassium shows marked stage‑specific patterns.

Proper fertilization is a key measure to coordinate vegetative and reproductive growth and to promote the accumulation of photosynthetic products. In practice, problems such as excessive fertilizer application, imbalanced nutrient ratios, and untimely application not only lead to nutrient losses and higher production costs but may also cause soil degradation and ecological issues.

(1) Seedling Stage

The seedling stage is an important period for root development and plant establishment. At this stage, the overall nutrient demand is relatively low, but the crop is very sensitive to nutrient supply. Nitrogen is the primary need, followed by phosphorus and potassium. Adequate nitrogen promotes leaf photosynthesis, while phosphorus and potassium enhance root activity and improve seedling resistance to adverse conditions. Insufficient nutrient supply during the seedling stage results in weak, stunted seedlings with slow growth that is difficult to compensate for later. On the other hand, sufficient nutrients encourage root expansion, laying a solid foundation for subsequent growth. During this period, fertilizer demand accounts for about 10%–15% of the total requirement over the entire growth cycle.

(2) Jointing Stage

At the jointing stage, maize enters a phase of rapid growth: stems elongate and leaf numbers increase, and nutrient demand rises markedly. The requirements for nitrogen, phosphorus, and potassium all increase, with nitrogen taking a larger share. Phosphorus and potassium help thicken the stems, thereby enhancing lodging resistance. If nutrients are insufficient at this stage, stems become slender, leaves turn yellow, and photosynthetic area expansion is limited. This stage accounts for about 30%–35% of total nutrient uptake and is one of the critical periods for fertilization.

(3) Ear Stage

The ear stage is the peak period of nutrient demand, as vegetative and reproductive growth occur simultaneously, and the differentiation and development of tassels and ears require large amounts of nutrients. Nitrogen demand reaches its maximum, while phosphorus and potassium requirements remain high. Adequate supplies of N, P, and K promote larger ears, more kernels, and higher grain‑set rates. Nutrient deficiency during the ear stage hinders ear differentiation, increases the incidence of bare tips, reduces kernel number, and directly affects yield. This stage accounts for about 40%–45% of total nutrient uptake and is the most critical fertilization period for yield determination.

(4) Flowering and Grain‑Filling Stage

During the flowering and grain‑filling stage, maize is primarily engaged in reproductive growth, and nutrient demand gradually declines, but a steady supply of nutrients is still necessary. Nitrogen demand decreases, while phosphorus and potassium become especially important: potassium facilitates the translocation of photosynthetic products to the grains, and phosphorus enhances grain plumpness. Insufficient nutrient supply at this stage leads to poor grain filling and reduced thousand‑kernel weight. This stage accounts for about 10%–15% of total fertilizer requirements, and it is essential to maintain a continuous nutrient supply to improve grain quality and increase yield.

The amount of fertilizer applied should be calculated based on the target yield, soil fertility, and fertilizer use efficiency. By testing soil nutrients, one can assess the soil’s nutrient‑supplying capacity, and then determine the total amounts of nitrogen, phosphorus, and potassium fertilizers according to the specific variety’s requirements and the expected yield. Generally, high‑yielding fields require higher nitrogen application, with corresponding amounts of phosphorus and potassium, while avoiding arbitrary increases in fertilizer rates. Adjust the application rates according to the soil’s available nutrient content to balance nutrient supply and demand, thereby improving fertilization efficiency.