North Carolina soils are diverse, ranging from sandy coastal plains to clay-rich Piedmont and acidic mountain soils. That diversity means micronutrient needs vary widely by region, cropping system, and management history. This article outlines the most commonly deficient micronutrients in North Carolina, explains how soil properties and management influence availability, describes effective supplement types and application methods, and provides practical diagnostic and management takeaways for growers, landscapers, and turf managers.
Soil texture, organic matter, pH, and drainage control micronutrient availability. North Carolina can be usefully divided into three broad soil regions for micronutrient planning:
Understanding the regional context helps prioritize which micronutrients to test for and which supplement strategies are likely to be effective.
Zinc is critical for enzyme activation, auxin synthesis, and protein production. Deficiency symptoms include interveinal chlorosis on younger leaves, stunted growth, and reduced yields. Zinc deficiencies are common on high-phosphorus soils, alkaline pH, or sandy low-organic soils.
Manganese is involved in photosynthesis and nitrogen metabolism. Symptoms include interveinal chlorosis that often appears on younger leaves, and brown speckling in severe cases. Acidic soils make Mn more available; liming often reduces Mn availability.
Iron is essential for chlorophyll synthesis. Fe chlorosis produces whitening of leaf tissue while veins remain green. Fe deficiencies are common in calcareous or limed soils with high pH and in waterlogged soils where root uptake is impaired.
Boron is critical for cell wall formation, pollen viability, and root development. Deficiency symptoms are crop-specific: blossom-end rot in vegetables, poor fruit set in tree crops, and death of growing points in brassicas. Sandy soils and soils with low organic matter are particularly likely to be low in boron.
Copper is involved in lignin synthesis and enzyme systems. Deficiency symptoms include stunted shoots, dieback, and pale foliage. Copper deficiencies are less common but can show up on organic, high-pH soils or where heavy phosphorus fertilization is used.
Molybdenum is needed for nitrate reduction and nitrogen fixation. Symptoms include pale or yellow leaves and reduced nodulation in legumes. Mo availability decreases at low pH; liming can increase Mo availability.
Chloride is an essential micronutrient for some crops (including tobacco and certain vegetables). Other elements such as cobalt (important for legumes in pasture systems) or silicon (beneficial in some crops) may be relevant in specific systems.
Soil testing and tissue testing are complementary. In North Carolina, use a reliable soil test (Mehlich-3 or the extractant recommended by your extension service) plus periodic plant tissue analysis for crops.
Timing matters: collect tissue samples at defined growth stages (e.g., early bloom for many crops) and avoid sampling immediately after foliar sprays. Interpret results with crop-specific sufficiency ranges; where tests show borderline values, consider a low-rate foliar application for rapid correction while addressing soil corrections for longer-term supply.
Micronutrient supplements fall into a few categories: inorganic salts, chelates, boron compounds, and seed or starter treatments. Each has pros and cons in North Carolina soils.
Common examples: zinc sulfate, manganese sulfate, iron sulfate, copper sulfate. Advantages: low cost and effective in acidic to neutral soils. Disadvantages: less effective in high-pH soils due to rapid precipitation and fixation. Sulfates also provide a small sulfur benefit.
Common chelating agents include EDTA, EDDHA, and DTPA. Chelates keep micronutrients in a soluble form that plants can uptake even in higher pH soils. EDDHA-Fe formulations are the most effective for iron in calcareous or limed soils. Chelates are more expensive but are the preferred option when pH limits availability.
Typical boron products are borax (sodium tetraborate) and sodium perborate derivatives. Boron is easy to leach in sandy soils; low-rate, frequent applications or foliar sprays timed to critical reproductive stages are common. Avoid over-application–crop sensitivity to boron toxicity is high.
Molybdenum is typically applied as sodium molybdate in low-pH soils or as seed treatment for legumes. Cobalt is used primarily in pasture systems where ruminant nutrition requires it; it is commonly applied as cobalt sulfate in small rates.
Foliar sprays are the fastest way to correct visible deficiencies and are particularly useful for zinc, manganese, and boron. Seed and starter treatments deliver micronutrients to the seedling and are useful for corn, soybeans, vegetables, and small-seeded crops. Be mindful of seed safety–boron and copper can be phytotoxic at high rates when in direct contact with seed.
Choosing method depends on crop, soil, and urgency.
Micronutrient availability is not isolated: nutrients interact.
Choose products from reputable suppliers and match the chemistry to soil conditions (chelate type to pH). Keep accurate records of materials applied, rates, timing, crop response, and soil and tissue test results. This will allow you to refine your program and avoid repeated unnecessary applications.
Micronutrient deficiencies in North Carolina are manageable with a strategic, test-based approach that considers soil region, texture, pH, crop, and history. Use soil tests to plan soil-applied corrections, tissue tests for in-season monitoring, foliar sprays for rapid remediation, and chelates where pH limits availability. Emphasize prevention through organic matter management and balanced fertilization rather than repeated emergency applications. When in doubt, consult county extension specialists for crop-specific rate recommendations and for interpreting local soil and tissue test results.