where descriptions and properties of soil horizons were stored. Linking the database
with soil maps enabled the generation of application maps in order to provide
information of public interest, such as the sensitivity to soil erosion or the landslide
hazard in a given area.
2.3.2 Mapping Approaches at the Landform Scale
Landforms are here defined as entities of parent rock with a similar topography.
Catena approach: For each study area, soil maps (1:50,000 scale) based on
transect sampling were created. In order to detect rules for soil distribution, the
transect lines aimed to cover the different soil parent materials, geomorphic units
and land use types in the respective areas. The number of sampling points used for
transect mapping was 72 in Mae Sa Mai (10.5 km
2 ), 62 in Huai Bong (6.8 km
2 ) and
58 in Bor Krai (8.5 km
2 ).
Grid-based randomized mapping: The grid-based randomized sampling
approach used was a modification of the random sampling approach used by Weller
(2002) in tropical southern Benin. In order to cover all landforms, topographic
positions and lithological units, a grid was laid over the research area and three
sampling points were randomly selected per grid cell. The Bor Krai site was chosen
to conduct a pilot study (Fig. 2.7). Soil samples were taken at 57 independent
points.
Indigenous knowledge approach: Indigenous soil knowledge, drawing on the
expertise of local stakeholders, mainly farmers in Mae Sa Mai, Huai Bong and Bor
Krai, was also used. The elicitation of farmers’ soil knowledge was based on the
Participatory Rural Appraisal (PRS) tool (Chambers 1992), and included the use of
semi-structured interviews, field and key informant interviews, participatory
mapping, group discussions and field walks. The survey was conducted during
the dry season (October to May) in 2004/2005 in Bor Krai (Schuler et al. 2006),
during which time experienced farmers were asked to say what criteria they use to
distinguish soil types. Soils on sites chosen by the farmers were sampled and
described according to both the local classification and the World Reference Base
for Soil Resources (IUSS Working Group WRB 2006). Next, farmers were asked to
Table 2.2 Excerpt from Soil
Database, Thailand. State:
01.02.2012
Parent rock
Soil profiles (n)
Auger (n)
Granite
108
63
Latite
2
1
Gneiss, migmatite
56
131
Slate
4
13
Marble
7
22
Conglomerate, breccia
2
27
Sandstone
24
120
Siltstone, mudstone, claystone
16
103
Limestone
15
229
2 Beyond the Horizons: Challenges and Prospects for Soil Science and Soil. . .
51
with soil maps enabled the generation of application maps in order to provide
information of public interest, such as the sensitivity to soil erosion or the landslide
hazard in a given area.
2.3.2 Mapping Approaches at the Landform Scale
Landforms are here defined as entities of parent rock with a similar topography.
Catena approach: For each study area, soil maps (1:50,000 scale) based on
transect sampling were created. In order to detect rules for soil distribution, the
transect lines aimed to cover the different soil parent materials, geomorphic units
and land use types in the respective areas. The number of sampling points used for
transect mapping was 72 in Mae Sa Mai (10.5 km
2 ), 62 in Huai Bong (6.8 km
2 ) and
58 in Bor Krai (8.5 km
2 ).
Grid-based randomized mapping: The grid-based randomized sampling
approach used was a modification of the random sampling approach used by Weller
(2002) in tropical southern Benin. In order to cover all landforms, topographic
positions and lithological units, a grid was laid over the research area and three
sampling points were randomly selected per grid cell. The Bor Krai site was chosen
to conduct a pilot study (Fig. 2.7). Soil samples were taken at 57 independent
points.
Indigenous knowledge approach: Indigenous soil knowledge, drawing on the
expertise of local stakeholders, mainly farmers in Mae Sa Mai, Huai Bong and Bor
Krai, was also used. The elicitation of farmers’ soil knowledge was based on the
Participatory Rural Appraisal (PRS) tool (Chambers 1992), and included the use of
semi-structured interviews, field and key informant interviews, participatory
mapping, group discussions and field walks. The survey was conducted during
the dry season (October to May) in 2004/2005 in Bor Krai (Schuler et al. 2006),
during which time experienced farmers were asked to say what criteria they use to
distinguish soil types. Soils on sites chosen by the farmers were sampled and
described according to both the local classification and the World Reference Base
for Soil Resources (IUSS Working Group WRB 2006). Next, farmers were asked to
Table 2.2 Excerpt from Soil
Database, Thailand. State:
01.02.2012
Parent rock
Soil profiles (n)
Auger (n)
Granite
108
63
Latite
2
1
Gneiss, migmatite
56
131
Slate
4
13
Marble
7
22
Conglomerate, breccia
2
27
Sandstone
24
120
Siltstone, mudstone, claystone
16
103
Limestone
15
229
2 Beyond the Horizons: Challenges and Prospects for Soil Science and Soil. . .
51