Soil the Foundation of an Organic Farm: Protecting & Building This Living Entity

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: 0.002 – 0.05 Millimeters Clay: Smaller – 0.002 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: • 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. • 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