🌾 Soil Health

Understanding Soil Structure

Soil is composed of four main components: minerals (45%), organic matter (5%), water (25%), and air (25%). The mineral portion consists of three particle sizes:

• Sand (0.05-2mm): Provides drainage and aeration but holds few nutrients
• Silt (0.002-0.05mm): Retains moisture and nutrients moderately well
• Clay (less than 0.002mm): Excellent nutrient retention but poor drainage

The ideal garden soil is loam - a balanced mixture of all three particle sizes (roughly 40% sand, 40% silt, 20% clay). This provides good drainage while retaining adequate moisture and nutrients.

Soil Biology: The Living Soil

Healthy biological soil teems with life. A single teaspoon contains billions of microorganisms:

• Bacteria: Break down organic matter and make nutrients available to plants
• Fungi: Form symbiotic relationships with plant roots (mycorrhizae) and decompose tough organic materials
• Protozoa: Feed on bacteria and release nutrients
• Nematodes: Many species are beneficial, feeding on bacteria and fungi
• Earthworms: Create channels for air and water, produce nutrient-rich castings
• Arthropods: Including springtails, mites, and beetles that shred organic matter

These organisms work together in the soil food web, cycling nutrients and creating soil structure. Biological gardening practices aim to nurture this underground ecosystem.

Soil pH and Nutrient Availability

Soil pH affects nutrient availability dramatically. Most vegetables prefer slightly acidic to neutral soil (pH 6.0-7.0). At extreme pH levels, certain nutrients become locked up and unavailable to plants.

Testing Soil pH

• Use a home test kit for quick results
• Send samples to a soil testing lab for comprehensive analysis (recommended every 2-3 years)
• Test multiple locations in your garden
• Test in early spring or fall for best results

Adjusting Soil pH Naturally

To raise pH (make soil less acidic):

• Add ground limestone (calcitic or dolomitic)
• Use wood ash (apply sparingly, very alkaline)
• Incorporate crushed oyster shells

To lower pH (make soil more acidic):

• Add elemental sulfur (slow-acting)
• Incorporate acidic organic matter (pine needles, oak leaves)
• Use sphagnum peat moss
• Apply coffee grounds moderately

Organic Matter: The Key to Soil Health

Organic matter is the cornerstone of biological gardening. It improves soil structure, increases water retention, provides slow-release nutrients, and feeds soil organisms.

Types of Organic Amendments

• Compost: Well-balanced nutrient source, improves structure
• Aged manure: High in nitrogen, adds beneficial microbes
• Leaf mold: Excellent soil conditioner, improves water retention
• Green manure/cover crops: Living organic matter, prevents erosion
• Worm castings: Rich in plant-available nutrients and beneficial microbes
• Biochar: Improves water retention and provides habitat for microbes

How Much to Add

Apply 2-3 inches of compost annually to garden beds. For new gardens or heavily depleted soil, incorporate 4-6 inches initially. Continue adding organic matter each season to maintain soil health.

Building and Maintaining Healthy Soil

Minimize Soil Disturbance

Excessive tilling destroys soil structure, disrupts fungal networks, and exposes carbon to oxidation. Practice no-till or low-till methods:

• Use broadforks to loosen soil without inverting layers
• Add organic matter to the surface rather than digging it in
• Let soil organisms incorporate amendments naturally
• Only disturb soil when planting or harvesting

Use Cover Crops

Plant cover crops between growing seasons to:

• Prevent erosion from wind and rain
• Suppress weeds naturally
• Add organic matter when cut and dropped
• Fix nitrogen (if using legumes like clover or vetch)
• Improve soil structure with deep roots

Practice Crop Rotation

Rotate plant families annually to prevent nutrient depletion, break pest and disease cycles, and maintain soil health. Avoid planting the same family in the same location for 3-4 years.

Mulch Consistently

Apply 2-4 inches of organic mulch around plants to:

• Retain soil moisture
• Suppress weeds
• Regulate soil temperature
• Add organic matter as it decomposes
• Protect soil from erosion

Solving Common Soil Problems

Compacted Soil

Symptoms: Poor drainage, stunted root growth, water pooling

Solutions:

• Use a broadfork to break up compaction without inverting soil
• Add generous amounts of compost
• Plant deep-rooted cover crops (daikon radish, alfalfa)
• Avoid walking on wet soil
• Create permanent pathways to minimize compaction

Poor Drainage

Symptoms: Standing water, waterlogged roots, fungal diseases

Solutions:

• Build raised beds (12-18 inches high)
• Incorporate sand and compost to improve structure
• Install drainage tiles or French drains
• Create swales to redirect water
• Choose plants adapted to wet conditions

Sandy Soil

Symptoms: Dries out quickly, nutrients leach away

Solutions:

• Add large amounts of compost (4-6 inches annually)
• Mulch heavily to retain moisture
• Use organic fertilizers that release nutrients slowly
• Irrigate more frequently with smaller amounts
• Consider adding clay if severely sandy

Clay Soil

Symptoms: Heavy, sticky, slow to drain, hard when dry

Solutions:

• Add coarse sand and compost in equal parts
• Gypsum can help break up clay particles
• Grow plants in raised beds above clay
• Avoid working soil when wet
• Plant cover crops with deep roots

Seasonal Soil Care Calendar

Spring

• Add 2-3 inches of compost to all beds
• Test soil pH and nutrient levels
• Turn in winter cover crops 2-3 weeks before planting
• Avoid working soil when too wet (forms a ball when squeezed)

Summer

• Apply mulch to retain moisture
• Side-dress heavy feeders with compost
• Monitor for signs of nutrient deficiency
• Plant cover crops in empty beds

Fall

• Plant overwintering cover crops
• Add leaves and organic matter to beds
• Apply lime if pH adjustment needed (works slowly over winter)
• Mulch perennials and garlic beds heavily

Winter

• Plan crop rotations for next season
• Review soil test results and plan amendments
• Let cover crops grow and protect soil
• Avoid walking on frozen or snow-covered beds