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

Section 3 • Living Soil, Integrated Soil Nutrient and Crop Managements
• Loamy soil forms a smooth ball or cylinder that is coherent. Alternatively, ball or
cylinder can be rolled into a thread (about 13-cm long, 0.6-cm diameter) and soil can
be easily worked between thumb and forefinger. Meanwhile, the thread can be formed
into ‘U’ or ring but cracks are formed. Alternatively, ‘I’ formed sticks on fingers with
a silky-soapy feel that predominates but may sometimes also have a slightly sandy feel.
• Clayey soil can be formed into a ball, which is smooth and plastic, and soil is stiff to
work between thumb and forefinger. Alternatively, soil can be rolled into a ribbon,
which forms a ring without cracking. Or soil takes on polish when moist and soil is
very sticky when wet and has a silky-soapy feel that predominates but sometimes a
few sand grains may also be felt.
• Soil Structure Classes. The peds or aggregates are classified according to their size
into soil structure classes as follows: (a) very fine or very thin; (b) fine or thin; (c)
medium; (d) coarse or thick; and (e) very course or very thick.
4. Present output of small groups to the big group. Conduct participatory discussion to allow
sharing of experiences among participants. Relate soil texture to water holding capacity,
abundance of soil organisms, soil organic matter content, and soil nutrient availability and crop
productivity.
5. Synthesize and summarize output of small groups into one big group output. Draw up
conclusions and recommendation from this exercise.
some suggested questions for processing discussion
❏ How will you differentiate soil texture from soil structure?
❏ Which soil samples had sandy, loamy, and clayey soil texture?
❏ Which soil texture exhibited higher water holding capacity? Which soil texture exhibited lower
water holding capacity?
❏ What physical, chemical, and biological soil characteristics were related to soil texture and soil
structure?
❏ Did you observe differences in the kind and number of organisms in soils exhibiting different
textures and structures?
❏ Do you think there will be differences in performance (e.g., plant growth, development, and
yield) of crops to be grown in soils of different textures and structures?
71