Meet the Secondary Macronutrients and the Micronutrients Your Plants Need

Meet the Secondary Macronutrients and the Micronutrients Your Plants Need

Essential Nutrition For Your Organic Garden

Micronutrients are essential for your plants, says Tricia in our video about secondary macronutrients and the micronutrients. While most gardeners are familiar with the primary macronutrients, nitrogen (N), phosphorus (P), and potassium (K), plants also need secondary macronutrients and micronutrients in smaller but equally important amounts. Understanding these nutrients and how to supplement them organically can transform your garden into a thriving ecosystem.

Primary Macronutrients: The Basics

The three numbers on fertilizer packages represent NPK, the primary macronutrients essential for plant growth.

  • Nitrogen (N): Supports vegetative growth and leaf production.
  • Phosphorus (P): Promotes root development and flower formation.
  • Potassium (K): Enhances plant vigor and overall health.

Primary macronutrients are the foundation, but plants need more than just NPK for optimal growth.

Secondary Macronutrients: The Unsung Heroes

Secondary macronutrients include calcium, magnesium, and sulfur. Though required in smaller amounts than NPK, they are critical for plant health.

  • Calcium: Builds strong cell walls and prevents disorders like blossom end rot in tomatoes. Add calcium through limestone powder, gypsum, oyster shell, or Kelzyme Calcium. Always test your soil pH before adding calcium. For example, gypsum lowers pH, while oyster shell lime raises it.

  • Magnesium: Supports chlorophyll production, essential for photosynthesis. Yellowing leaves with green veins often indicate magnesium deficiency. Organic sources include dolomite, K-Mag, and Azomite.

  • Sulfur: Builds proteins and improves plant resilience. Sulfur is released naturally as green materials decompose, but it can also be added using gypsum, iron sulfate, or straight sulfur products like Tiger Organic.

 

Micronutrients: The Trace Elements

Micronutrients, also known as trace elements, are needed in small amounts but play vital roles in plant development. Let’s explore their functions and sources:

  • Boron: Regulates nutrient uptake and supports seed and fruit development. Add boron via powdered boron.
  • Copper: Boosts root metabolism and aids reproduction. Found in copper sulfate or chelated copper.
  • Chloride: Assists in plant metabolism and improves drought resistance. Chloride is often present in irrigation water.
  • Iron: Essential for chlorophyll production. Deficiency symptoms include yellow leaves with green veins. Add iron via iron sulfate or chelated iron.
  • Manganese: Breaks down carbohydrates and supports enzyme activity. Found in manganese sulfate.
  • Molybdenum: Aids nitrogen uptake and use. Use molybdenum-enriched fertilizers if needed.
  • Zinc: Helps convert carbohydrates into sugars and supports growth enzymes. Add zinc through zinc oxide, zinc sulfate, or zinc chelate.

 

How to Test and Supplement Nutrients

Before adding secondary macronutrients or micronutrients, conduct a lab soil test to identify deficiencies. The availability of these nutrients can be affected by pH levels or imbalances with other elements. For example, excessive magnesium can limit calcium uptake, even if calcium levels are adequate.

Once deficiencies are identified, choose organic fertilizers to address them. Some multi-nutrient supplements that provide a range of micronutrients include:

  • Kelp Meal: A slow-release source of micronutrients.
  • Glacial Rock Dust: Improves soil mineral content over time.
  • Azomite: A natural mineral supplement rich in trace elements.
  • Liquid Kelp: Provides fast-acting nutrients for immediate results.

  

Practical Tips for Organic Fertilization

  1. Understand Your Soil: Regular soil testing is essential to identify deficiencies and avoid over-supplementation.
  2. Follow Application Rates: Too much of a good thing can harm plants. Use fertilizers sparingly and as directed.
  3. Maintain Soil pH: Nutrient uptake is heavily influenced by pH levels. Most plants thrive in a slightly acidic to neutral pH range (6.0–7.0).
  4. Rotate Crops: Crop rotation prevents nutrient depletion and helps maintain a balanced soil profile.
  5. Incorporate Compost: Organic matter improves soil structure and provides a natural source of micronutrients.

Signs of Nutrient Deficiencies

Identifying deficiencies early can save your plants. Common symptoms include:

  • Nitrogen Deficiency: Pale green leaves and stunted growth.
  • Phosphorus Deficiency: Purplish leaves and poor root development.
  • Potassium Deficiency: Brown leaf edges and weak stems.
  • Calcium Deficiency: Blossom end rot in tomatoes and cucumbers.
  • Magnesium Deficiency: Yellowing leaves starting from the edges.
  • Iron Deficiency: Yellow leaves with green veins on new growth.

 

Sustainable Gardening with Nutrient Management

By understanding and managing nutrient needs, you can grow a garden that is not only productive but also environmentally sustainable. Organic fertilizers and soil amendments ensure that plants receive the nutrients they need without harming the ecosystem.

Start with a soil test, choose the right amendments for your garden, and monitor plant health throughout the growing season. With the proper balance of primary macronutrients, secondary macronutrients, and micronutrients, your garden will thrive and reward you with bountiful harvests.

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3 comments

What about iron?

Nathan Lassig

Kenny, some labels will list percentages for things like calcium, sulfur, sometime magnesium. You can find it on the product label, it the percentage is high enough.

Suzanne at GrowOrganic.com

I’m looking for a list of percentages of secondary macronutrients that are available in common organic soil amendments. Any ideas where I could find that? Thanks.

Kenny

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