1. Soil the Foundation of an Organic Farm: Protecting & Building This Living Entity
Prepared by:
L. Robert Barber, & Ilene Iriarte
For:
Guam Cooperative Extension Service & Guam Department of Agriculture
Funding provided by:
United States Department of Agriculture Natural Resources Conservation Service, Western Region Sustainable Agriculture Research and Education, Administration for Native Americans,, & Sanctuary Incorporated

2. Soil Components Mineral Content: Sand: 0.05 – 2 Millimeters
Silt: – 0.05 Millimeters
Clay: Smaller – Millimeters
25% AIR
45% MINERAL
25% WATER
5% ORGANIC MATTER

3. Why is Organic Matter Important?
Provides environment and food for beneficial organisms
Better aeration, water penetration
Greater water holding capacity
Holds soil particles together (forms aggregates)
Suitable environment for beneficial organisms
Retains & releases nutrients

4. Soil Structure Good Soil Structure: Poor Soil Structure:
Good percentage of sand, silt, and clay
Ample pore space: Aeration & Drainage
Easy root penetration
High in soil organisms activity
Poor Soil Structure:
Compacted
Small amount of pores
Shallow soil
Low in soil organisms activity

5. Soil Organisms Majority of microorganisms in soil help crops
Some Large Soil Organisms (visible):
Earthworms
Millipedes
Beatles
Slugs
Some Microorganisms (not visible):
Bacteria
Fungi (Mycorrhizae)

6. Soil Organisms Decompose organic matter Help build the soil aggregates
Promote aeration & deep rooting
Release nutrients into soils
Help control pests & diseases

7. Factors Influencing Soil Fertility
Soil depth
Water Availability
Water holding capacity
Drainage
Water Logging
Aeration
Root growth & microbial activity pH
Acidic & Alkaline

8. Factors Influencing Soil Fertility
Mineral Composition
Soil structure
Organic Matter
Soil life
Soil Organisms Activity
Nutrient availability
Water retention
Decomposition of organic matter

9. Improving & Maintaining Soil Fertility
Conservation Methods
Maintain soil ground cover
Contour practices & tillage
Nutrient Management
Nitrogen Fixing Trees (or other plants)
Rotations

10. How to Increase Organic Matter
Incorporate crop remains into the field
Compost
Mulch
Animal manures
Green manures & Cover crops
Crop Rotation
Reduce Tillage
Agroforestry Systems

11. Soil Sampling Why do you need to take soil samples?
Nutrients content
Nutrient are limited or excess
When should you take soil samples?
Beginning of each growing season
Tools needed for sampling.
Hand trowel or shovel
Zip lock bag

12. Soil Sampling Identifying differences in your field. Sampling pattern.
Not all fields have uniform soils
Split the fields and take separate samples
Color, texture, drainage, and yield differ
Sampling pattern.
Take several samples
Walk through your field in a “W” pattern
If the samples are uniform mix them together

13. Soil Sampling Sampling and Submission Procedures
Dig a V-shaped hole about 6-8 inches deep
Place the soils in a zip lock bag
Write your name and field location
Fill out a soil sample information sheet at the University of Guam Cooperative Extension Service
Drop off your samples at the Cooperative Extension Service