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eturn to table of

eturn to table of contents NUTRIENT UPTAKE IN CORN by Stephen D. Strachan, Ph.D., DuPont Research Scientist SUMMARY • Healthy corn crop growth requires a variety of nutrients, 16 of which are absolutely essential for plant development. • Regulation of nutrient uptake in variant texture, pH, and chemical properties of the soil is a physiological process that allows the corn plant to maintain a proper nutrient balance. • Nutrient uptake from the soil is a seven-step process, requiring input from the plant with participating elements of the roots, energy input, and vascular tissues. • Nutrient concentration of internal root cells regulates how much additional nutrient must be transported through the plasma membranes. • Plant growth results because of the transportation of these nutrients from internal root cells to other portions of the plants via the xylem and phloem. • Agronomic practices that best support this nutrient extraction process to obtain maximum grain yield include eliminating compaction, draining wet soils, monitoring for nutrient deficiency, and maintaining adequate water supply to the growing crop. 56

eturn to table of contents INTRODUCTION Sixteen nutrients are essential for corn growth. Carbon and oxygen, the most abundant nutrients, are extracted from carbon dioxide and molecular oxygen, respectively, in the atmosphere. Hydrogen is extracted from degradation of water molecules during photosynthesis. As water molecules break down into hydrogen and oxygen, hydrogen is initially incorporated to make sugar. Oxygen is either incorporated for corn growth or released into the atmosphere as a by-product. Five of the six macronutrients – calcium, magnesium, nitrogen, phosphorus, and potassium and the seven micronutrients – boron, chlorine, copper, iron, manganese, molybdenum, and zinc – are extracted from soil. The secondary macronutrient sulfur is extracted mostly from soil but may also be extracted from the atmosphere depending on the concentration of sulfur-containing compounds. Mature corn, no matter which hybrid is produced or in what soil type the hybrid is grown, contains a relatively consistent range of each of these 16 nutrients (Figure 1) (Latshaw and Miller, 1924). Magnesium