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

Exercise No. 3.03 50
SOIL PROFILE ANALYSIS: A GUIDE IN UNDERSTANDING
SOIL FERTILITY AND PRODUCTIVITY IN ORGANIC
VEGETABLE FARMING
BaCKGroUND aND raTIoNalE
Examination of a vertical section of a soil in a field reveals
presence of more or less distinct horizontal layers. Such
a section is called a soil profile, and individual layers are
regarded as soil horizons. Every well-developed, undisturbed
soil has its own distinctive profile characteristics, which are
used in soil classification and in judging soil fertility and
productivity 51 . Soil fertility refers to inherent capacity of a
soil to supply nutrients to plants in adequate amounts and in
suitable proportions. Soil productivity, on other hand, is related
to the soil’s ability to yield crops. It is a broader term since soil
fertility is only one of the factors that determine magnitude of crop yields.
60
Field Guide of Discovery-based Exercises for Organic Vegetable Production
when is this exercise most
appropriate?
ɶ In FFS, TOT, and
VST sessions, before
land preparation
as component of
‘Integrated Nutrient
Management’ and ‘Soil
Biodiversity’ topics; and
ɶ When farmers want
to learn from others
some innovative soil
management practices
and do hands-on of soil
profile analysis.
The topsoil, being near surface, is a major zone of root development. It carries much of nutrients
available to plants, and it supplies a large share of water used by crops. As a layer that is plowed
and cultivated, it is subject to manipulation and management. Proper cultivation and incorporation
of organic residues may modify its physical condition. It can be treated easily with organic solid
fertilizers such as vermi-compost, and it can be drained. In short, its fertility and to a lesser degree,
its productivity, may be raised, lowered, or satisfactorily stabilized at levels consistent with economic
organic vegetable crop production.
An analysis, therefore, of a soil profile is important in deciding appropriate cultural management
practices that will enhance organic vegetable crop productivity. Farmers’ way of assessing soil
profile had evolved through years of experience. In FFSs, these experiences must be shared among
farmers and facilitators to gain new knowledge in improving soil fertility and productivity. This
exercise was designed to achieve this particular objective.
50 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. pp64-67.
51 Brady, N.C. 1985. The nature and properties of soils. 9 th Edition. Macmillan Publishing Co., 866 3 rd Ave., New York, New York, U.S.A. pp1-33.