Teaming with Nutrients

1. Plants require 17 essential nutrients for growth and reproduction

Only seventeen elements are needed by plants to grow and reproduce.

Macronutrients and micronutrients. Plants need larger quantities of macronutrients and trace amounts of micronutrients. The macronutrients include:

• Carbon, hydrogen, and oxygen (from air and water)
• Nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur (from soil)

Micronutrients, needed in smaller quantities, include:

• Boron, chlorine, copper, iron, manganese, zinc, molybdenum, and nickel

Each nutrient plays a specific role in plant growth and development. For example, nitrogen is crucial for protein synthesis and chlorophyll production, while phosphorus is essential for energy transfer and DNA formation. Understanding these roles helps gardeners provide balanced nutrition for optimal plant health.

2. Soil biology and chemistry influence nutrient availability

Compost, on the other hand, has a very high percentage of organic matter, and so it generally has a pH in the range that is better suited for plant growth, 6.5 to 7.5.

Soil pH affects nutrient availability. The pH scale ranges from 0 (acidic) to 14 (alkaline), with 7 being neutral. Most plants thrive in slightly acidic to neutral soils (pH 6.0-7.0) because this range optimizes nutrient availability. At extreme pH levels, certain nutrients become less available or even toxic to plants.

Soil organic matter is crucial. Organic matter improves soil structure, water retention, and nutrient availability. It provides food for beneficial soil microorganisms, which in turn:

• Break down organic materials into plant-available nutrients
• Form symbiotic relationships with plant roots (e.g., mycorrhizal fungi)
• Improve soil structure through their activities

Maintaining a healthy soil ecosystem with proper pH and organic matter content ensures that plants can access the nutrients they need for growth and development.

3. Root systems and mycorrhizal fungi are crucial for nutrient uptake

Some experiments have suggested that these fungi can deliver 80 percent of a plant's phosphorus, 60 percent of its copper, 25 percent of its nitrogen, 25 percent of its zinc, and 10 percent of its potassium.

Root architecture matters. Plants develop extensive root systems to explore the soil for water and nutrients. Root hairs, which are extensions of epidermal cells, greatly increase the surface area for nutrient absorption. Different plants have different root architectures adapted to their specific environments and nutrient needs.

Mycorrhizal partnerships are vital. Over 80% of land plants form symbiotic relationships with mycorrhizal fungi. These fungi:

• Extend the plant's reach into the soil, accessing nutrients beyond the root zone
• Efficiently absorb and transport nutrients, especially phosphorus, to the plant
• Receive carbohydrates from the plant in exchange for their services

This mutually beneficial relationship significantly enhances a plant's ability to acquire nutrients, especially in nutrient-poor soils. Gardeners can support mycorrhizal partnerships by avoiding excessive tillage, using organic fertilizers, and inoculating soils with mycorrhizal fungi when necessary.

4. Cellular membranes regulate nutrient transport into plants

Nutrient ions travel along the same pathways as water into the xylem.

Selective permeability is key. Plant cell membranes, particularly the plasma membrane, control what enters and exits the cell. This selective permeability is crucial for maintaining proper nutrient concentrations and cellular function.

Nutrient transport mechanisms include:

• Passive transport: Diffusion and osmosis (no energy required)
• Facilitated diffusion: Carrier proteins assist movement (no energy required)
• Active transport: Energy-dependent movement against concentration gradients

Membrane proteins play crucial roles. Specialized proteins embedded in the membrane facilitate nutrient uptake:

• Channel proteins: Allow specific ions to pass through
• Carrier proteins: Bind to nutrients and change shape to transport them
• Pump proteins: Use energy (ATP) to move nutrients against concentration gradients

Understanding these mechanisms helps explain why some nutrients are more readily absorbed than others and how plants can selectively uptake essential elements while excluding potentially harmful substances.

5. Photosynthesis and respiration drive nutrient assimilation

Carbohydrates are produced by plants using photosynthesis.

Photosynthesis: The foundation of plant nutrition. This process converts light energy into chemical energy, producing glucose from carbon dioxide and water. Key points:

• Occurs in chloroplasts, primarily in leaf cells
• Requires chlorophyll, which contains magnesium
• Produces oxygen as a byproduct

Respiration: Energy release and nutrient utilization. Plants break down glucose through respiration to release energy for growth and maintenance. This process:

• Occurs in mitochondria of all living plant cells
• Requires oxygen and produces carbon dioxide
• Generates ATP, the energy currency of cells

The energy and carbon skeletons produced through these processes are essential for:

• Synthesizing amino acids, proteins, and other complex molecules
• Powering active transport of nutrients across membranes
• Driving cellular processes necessary for growth and reproduction

Understanding these fundamental processes helps gardeners appreciate the importance of providing adequate light, water, and nutrients to support healthy plant growth.

6. Nutrient mobility within plants affects deficiency symptoms

Where the symptoms of nutrient deficiencies occur, such as wilted growth tips or yellowed older leaves, depends, in part, on the mobility of the lacking nutrient.

Mobile vs. immobile nutrients. Nutrients have varying degrees of mobility within plants, which affects where deficiency symptoms appear:

Mobile nutrients:

• Nitrogen, phosphorus, potassium, magnesium
• Deficiency symptoms appear first in older leaves as the plant redistributes these nutrients to new growth

Immobile nutrients:

• Iron, calcium, boron, manganese
• Deficiency symptoms appear first in new growth because these nutrients cannot be easily moved from older tissues

Recognizing deficiency symptoms. Common signs of nutrient deficiencies include:

• Chlorosis (yellowing of leaves)
• Necrosis (death of tissue)
• Stunted growth or deformed leaves

By observing where symptoms appear and their specific characteristics, gardeners can often diagnose nutrient deficiencies and take corrective action. However, soil testing is always recommended for accurate diagnosis and treatment.

7. Soil testing is essential for effective fertilization

Have a soil test done before you set up a feeding program.

Knowledge is power. Soil testing provides crucial information about:

• Nutrient levels (macro and micronutrients)
• pH
• Organic matter content
• Cation exchange capacity (CEC)

This information allows gardeners to:

• Identify specific nutrient deficiencies or excesses
• Determine appropriate fertilizer types and application rates
• Avoid over-fertilization, which can harm plants and the environment

Regular testing is key. Soil should be tested:

• Before establishing new gardens or lawns
• Every 2-3 years for established gardens
• When persistent plant health issues occur

Many universities and commercial laboratories offer affordable soil testing services. By following test recommendations, gardeners can provide optimal nutrition for their plants while minimizing environmental impact and unnecessary expenses.

8. Natural fertilizers support soil health and plant nutrition

Organic fertilizers are, by definition, full of organic matter, which supports the creation and maintenance of good soils and healthy, diverse soil food webs.

Benefits of natural fertilizers. Compared to synthetic fertilizers, natural options offer several advantages:

• Slow-release of nutrients, reducing leaching and runoff
• Improvement of soil structure and water-holding capacity
• Support for beneficial soil microorganisms

Common natural fertilizers include:

• Compost
• Animal manures
• Bone meal
• Fish emulsion
• Kelp meal

Balanced approach to fertility. Natural fertilizers often contain a broader spectrum of nutrients than synthetic options. This helps provide more balanced plant nutrition and reduces the risk of creating nutrient imbalances in the soil.

While natural fertilizers may work more slowly than synthetic options, they contribute to long-term soil health and sustainable plant growth. Gardeners can combine different natural fertilizers to create custom blends tailored to their specific soil and plant needs.

9. Timing and application methods impact fertilizer efficacy

Key times to think about are seed germination, transplanting outdoors, flower development, and the first appearance of fruit.

Timing matters. Plants have different nutrient needs throughout their life cycle. Proper timing of fertilizer applications ensures nutrients are available when plants need them most:

• Early season: Higher nitrogen for vegetative growth
• Mid-season: Balanced nutrition for overall plant health
• Late season: Higher phosphorus and potassium for flower and fruit development

Application methods affect nutrient availability. Common fertilizer application techniques include:

• Broadcasting: Spreading fertilizer over a large area
• Banding: Placing fertilizer in a narrow band near plant roots
• Side-dressing: Applying fertilizer alongside growing plants
• Foliar feeding: Spraying liquid fertilizer on plant leaves

Each method has advantages and is suited to different situations. For example, banding is effective for phosphorus, which is less mobile in soil, while broadcasting works well for more mobile nutrients like nitrogen.

By considering both timing and application method, gardeners can maximize the efficiency of their fertilizer use, promoting healthy plant growth while minimizing waste and environmental impact.

Last updated: April 17, 2025