Corn, or maize, is one of the world’s most widely grown and economically significant crops, serving as a foundational source for food, feed, and fuel. Achieving the full genetic potential of this high-demand plant requires a precise supply of nutrients throughout its life cycle. Corn requires 17 elements to complete its growth cycle, with 14 of these minerals typically supplied by the soil. Meeting the plant’s substantial and fluctuating requirements for these elements demands careful management of soil fertility. Understanding the function of each nutrient is necessary for optimizing crop health and maximizing grain yield.
Essential Primary Macronutrients
The plant requires three primary macronutrients in the largest quantities: nitrogen, phosphorus, and potassium. Nitrogen (N) is the most consumed nutrient, serving as a major component of amino acids, the building blocks of proteins and enzymes. It is integral to the chlorophyll molecule, driving photosynthesis and rapid vegetative growth. Adequate nitrogen is necessary for cell division, structural integrity, and the development of the entire plant structure.
Phosphorus (P) is involved in energy transfer, acting as a component of the plant’s energy currency, adenosine triphosphate (ATP). This energy fuels virtually all metabolic processes, including photosynthesis and respiration. Phosphorus is also a structural part of DNA and RNA, ensuring proper cell development. Furthermore, this element promotes vigorous seedling growth, enhances root development, and contributes to the structural integrity of the stalk.
Potassium (K) is required in large amounts, nearly as much as nitrogen, but its function is regulatory rather than structural. It manages the movement of water, nutrients, and carbohydrates throughout the plant tissue. Potassium regulates the opening and closing of stomata, controlling water transpiration and gas exchange. It also plays a role in activating numerous enzymes and strengthens cell walls, enhancing the plant’s ability to resist disease and maintain standability.
Secondary Macronutrients
Corn requires three secondary macronutrients: calcium, magnesium, and sulfur. Magnesium (Mg) is linked to energy production, as it forms the central core of the chlorophyll molecule. Without magnesium, the plant cannot manufacture chlorophyll, directly impairing photosynthesis. It also activates many enzyme systems and is involved in the synthesis of carbohydrates and proteins.
Calcium (Ca) is a relatively immobile nutrient, requiring continuous supply to new growth for proper development. Its primary function is maintaining cell wall structure, forming cross-links with pectin to provide rigidity and strength to the plant tissue. This is important for root development and the structural support of developing kernels. Calcium also helps regulate nitrate uptake.
Sulfur (S) works closely with nitrogen and is essential for the plant to efficiently utilize applied nitrogen. It is a structural component of the amino acids cysteine and methionine, making it indispensable for protein synthesis. Sulfur is also necessary for the formation of chlorophyll, and a deficiency can resemble nitrogen deficiency.
Critical Micronutrients
Micronutrients are required in very small amounts, but their presence is mandatory for the plant to complete its life cycle. Zinc (Zn) is one of the most important micronutrients for corn, which is highly sensitive to deficiency. It is a component of numerous enzymes and plays a direct role in the production of growth hormones that regulate stem elongation and leaf expansion. Zinc is also involved in carbohydrate and protein metabolism.
Iron (Fe) is essential for the formation of chlorophyll and assists in the plant’s energy production processes. It is a constituent of several enzymes and is involved in nitrate reduction. Manganese (Mn) is necessary for photosynthesis, as well as for the plant’s respiration and nitrogen assimilation pathways.
Boron (B) has a specialized function in reproductive development, necessary for proper cell division and the formation of healthy seeds. It is directly involved in pollen tube growth and successful pollination. A shortage of these trace elements can severely limit growth and reduce grain yield.
Nutrient Demand Across Growth Stages
The timing of nutrient availability is as important as the total amount supplied over the season. Corn’s demand is relatively low during the early vegetative stages (V1–V6), as the plant is primarily establishing its root system. Phosphorus is important during this initial period to maximize root development and shoot growth, often necessitating a starter application near the seed.
The plant’s physiology changes dramatically around the V6 stage, marking the beginning of the rapid growth phase, which lasts until tasseling (VT). This period sees the highest daily nutrient uptake rates for most elements, particularly nitrogen and potassium. For a high-yielding corn crop, the daily demand for nitrogen can peak between the V10 and V14 stages, requiring the largest fraction of the total nitrogen needed for the season.
Potassium accumulation is concentrated during this vegetative phase, with over 80% of the total potassium absorbed before the silking stage (R1). This early demand supports stalk strength and the plant’s water regulation system during its most vulnerable growth period. While phosphorus is needed early, its uptake continues steadily, with roughly half of the total accumulation occurring after flowering during the grain-fill stages (R1–R6).
During the reproductive stages (R1–R6), the focus shifts to maximizing grain development and kernel fill. Although the plant’s overall daily nutrient uptake from the soil slows after the R1 stage, the demand for nutrients to be partitioned into the developing grain remains high. Boron and zinc remain important to support successful pollination, grain set, and sustained uptake during the grain-filling period. A sufficient supply of nitrogen during grain fill is also needed to ensure good protein levels and prevent the plant from cannibalizing nitrogen from the stalks and leaves, which can lead to weak stalks and lodging.