Soil Management in San Diego- Urban Composting
Building Better Soils
Characteristics of “Healthy Soils”
• Granular Structure• Organic matter suitable for plant
palette• Nutrient and water reservoirs are
sufficient to meet plant needs• Friable, good tilth
Building Better Soils
“Unhealthy Soils”• Compacted, poor structure• Heavy salt load• Insufficient organic matter present
for good plant growth, increased water holding capacity and to support soil life
• Plants subject to increased pathogen and pest pressure
Building Better Soils
Challenges of San Diego Soils
• High Salts• Low Organic Matter• Variable pH• Sporadic Rainfall• Salty Water• Human Activity
Building Better Soils
Soil & Water ChemistryTotal Salts in the Soil/Water Solution
Beneficial– Potassium, Calcium , Magnesium– Sulfates, Nitrates
Damaging– Sodium– Chloride– Boron in excess
Building Better Soils
Physical Characteristics• Texture
– Percent of Sand, Silt and Clay– Percent of Organic Matter
• Structure– Arrangement of Particles
• Compaction• Drainage
Building Better Soils
Importance of Soil StructureMicro-Aggregates
– clay microstructures, silt-size microaggregates, particulate organic matter, plant and fungus debris, and mycorrhizal fungus hypha
– Relatively stable – Building blocks for macro-aggregates
Building Better Soils
Importance of Soil StructureMacro-Aggregates• Bound by fungi hyphae, root fibers, and
polysaccharides • Reduce bulk density of the soil • Are less stable than micro-aggregates,
easily subject to compaction
Building Better Soils
Importance of Soil StructureMacro-aggregates provide macro-pores
– Drainage– Ability to leach– Air space– Reduces water molds and root rot
Building Better Soils
Organic Mulch Reduces Soil Compaction
• Using mulch helps reduce compaction. It acts like a sponge to absorb weight and water
• Shatters rain drops • Supplies food for microbes, which
encourages micro and macro aggregation
Conservation & Source Reduction
• The first and most important step!
• Saves the most money, reduces infrastructure costs, reduces demand for energy and resources.
Resource or Waste
What do we do with what's left over?
Bottles, Cans, and Paper
Transfer
Broker
Recycling Facility
End User
Waste
Transfer
Landfill
Organics
El Corazon Compost Facility
Back to Local Soils
Collection
Pathogen Reduction ProcessThe Title 14 “Process to Further
Reduce Pathogens” is a natural activity that uses the heat generated by microbial activity to kill both plant and human pathogens.– 131° F for at least 15 days– Turn at least 5 times during this process– Water and nitrogen must be present in
sufficient quantities
Using PRFP to Mitigate Pesticides, Weed Seeds and
Insect Larvae
• Many pesticide residues, weed seeds and insects are controlled during the same time frame
• More resistant pesticides residues may require longer composting periods
Building Better Soils
Quality Control
• On-Site Analysis– pH– Moisture– Oxygen– Solvita– Mineral Nitrogen– Microscope