Field Guide of Discovery-based Exercises for - Aseanipm ...

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Field Guide of Discovery-based Exercises for Organic Vegetable Production
5 Group II to visually observe soil texture and structure of brush land (e.g., plants grow as
tall as 1-2 meters)
5 Group III to visually observe soil texture and structure of grassland (e.g., plants grow less
than 1 meter tall)
5 Group IV to visually observe soil texture and structure of crop land (e.g., organic vegetable
crops are grown)
5 Group V to visually observe soil texture and structure of barren land (e.g., no crop or other
plant is grown)
2. Each group should mark a 1-m 2 quadrant of soil surface with the use of pegs and nylon twine to
secure corners of quadrant and perform the following activities:
5 Pull out and ‘de-soil’ (e.g., ipagpag or shake to retain soil in roots) weeds inside quadrant.
5 Remove soil litters and organisms (e.g., rove beetles, ants, millipede, earthworms, etc.)
found in soil surface.
5 Scrape soil within two inches depth of quadrant and place in separate plastic bag.
5 List down all pertinent observations.
3. Go back to processing area. Brainstorm in small groups to modify, improve, if necessary, or
implement as the procedure suggested below to determine soil texture and structure:
5 Get air-dried soil samples from respective quadrants, pulverize, and weigh 1-kg soil.
5 Take soil sample sufficient to fit comfortably into palm.
5 Remove foreign bodies (e.g., roots, seeds, insects, etc.) and soil materials greater than 2
mm (e.g., gravel, etc,).
5 Moisten sample uniformly, a little at a time; knead soil until it just begins to stick to fingers
(e.g., so-called sticky point).
5 Break down soil into its individual particles so that no aggregates remain; some soils need
much working.
5 Work soil in hand and squeeze soil between thumb and forefinger to determine if it is one
of the following:
• Sandy soil has nil to very little coherence. Alternatively, a rough ball can be formed,
which breaks easily when squeezed lightly between thumb and fingers. Alternatively, a
rough cylinder (about 5-cm long, 1.5-cm diameter) can be formed out of the soil but the
cylinder is not smooth and cracks form and soil has a sandy feel, which predominates
and is not very sticky.