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

Exercise No. 3.14 81
MAINTAINING SOIL BIODIVERSITY AS A SOIL
MANAGEMENT OPTION FOR IMPROVING ORGANIC
VEGETABLE PRODUCTIVITY
BaCKGroUND aND raTIoNalE
The soil harbors varied population of living organisms. Both
animals and plants are abundant in soils. Moreover, most
organisms vary so much both in number and in amount as
to make precise statements impossible. This condition is
known as soil biodiversity. In any case, the quantity of living
organism including plant roots is sufficient to influence
profoundly physical and chemical trend in soil changes.
108
Field Guide of Discovery-based Exercises for Organic Vegetable Production
Activities of soil organism range from largely physical disintegration of plant residues by insects
and earthworms to eventual complete decomposition of these residues by smaller organisms such
as bacteria and fungi. Accompanying these decaying processes is the release of several nutrient
elements, including nitrogen, phosphorus and sulfur, from these decomposed organic matters. By
contrast, conditions in nature are such that organisms need these elements for their growth and a
reversal occurs (e.g., elements are converted again into organic forms not available to higher plants).
Thus, soil biodiversity is important so that the above process, known as biocycling, can proceed in
a faster pace. Through this process, residues and wastes are incorporated into soils, disintegrated
and decomposed, and pertinent product of organic matters are then taken up by plants to stimulate
further biomass production and thus, improve crop productivity 82 . In FFSs, farmers and facilitators
can learn from each other many appropriate cultural practices that will enhance soil biodiversity
through participatory, discovery-based and experiential approaches, hence this exercise.
How long will this exercise take?
when is this exercise most
appropriate?
ɶ In FFS, TOT, and VST
sessions, as component of
the topic on ‘Ecosystem’;
and
ɶ When farmers want to
learn more about the
role of soil organisms
in further sustaining
productivity in growing
organic vegetables.
• Thirty minutes to one hour for field walks and observations of soil biodiversity for different soil
ecosystem in adjoining fields of learning field; and
• Thirty minutes to one hour brainstorming session in processing area.
81 Adapted from Callo, Jr., D.P., L.B. Teofilo, and H.A. Tauli (eds). 2002. Field Guide of Discovery-based Exercises for Vegetable IPM, Volume II. SEAMEO
Regional Center for Graduate Study and Research in Agriculture (SEARCA), Los Baños, Laguna, Philippines. pp83-86.
82 Brady, N.C. 1985. The nature and properties of soils. 9 th Edition. Macmillan Publishing Company, 866 3 rd Avenue, New York, New York, USA. pp1-
33.